CHANGELOG.md

Change Log

MDL SDK 2024.0.1 (377400.2109): 18 Jul 2024

ABI compatible with the MDL SDK 2024.0.1 (377400.2109) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• MDL 1.9 Language Specification

  • Updated version to 1.9.
  • declarative and struct_category as new reserved words.
  • Added the concept of declarative structure definitions with and without a structure category to the conventional structure definitions.
  • Added the definition for the assignment operator (=) for declarative structs with and without a structure category.
  • Restricted the type cast operator on structure types to conventional structure types.
  • Added declarative functions.
  • Restricted overload resolution on material definitions.
  • Extended overload resolution to define functions whose signature is a prefix of others as more specific.
  • Specified that function overload sets can contain both declarative and non-declarative functions.
  • Clarified that the auto return type for functions is allowed on function definitions and not on function declarations.
  • Defined material definitions as functions returning a declarative structure definition of the material_category structure category.
  • Defined the builtin material type as a declarative structure type with the material_category structure category.
  • Changed the ior field of the builtin material type to be of varying type and not uniform color anymore.
  • Defined the builtin distribution function types bsdf, edf, vdf, and hair_bsdf as a declarative structure type without structure category and without fields.
  • Redefined the compound types in the material type to declarative structure types without structure category.
  • Added rounding function round_away_from_zero() and clarified rounding behavior of round().
  • Removed the statement for microfacet BSDF models that they become black in transmission mode if the ior values indicate total interior reflection.

• General

  • The material.ior field is now varying for all versions of MDL (not only for MDL 1.9). This avoids to break the ABI to the renderer, since there is still only one material type. The new method IMdl_configuration::set_material_ior_frequency() allows to revert that change as a workaround for rare compatibility problems with MDL modules authored for MDL versions before 1.9. Please note that this will switch the field to uniform for all version (including MDL 1.9). Note further that this option cannot be set dynamically, it is only possible to set it at SDK start time.

  • Added CMake option MDL_BUILD_SDK which is ON by default. If set OFF only the MDL Core and mdlc will be built.

  • The alpha channel is now always treated as linear, independent of the gamma value specified for the remaining channels.

  • Added new AOV(Arbitrary Output Variables) support. It allows rendering applications to produce customized data in addition to the usual image output buffers:

    • The interface IStruct_category has been added to represent the new concept of struct categories. The new interface IStruct_category_list represents an ordered collection of struct categories identified by name or index.
    • The new methods IType_struct::get_struct_category() and IModule::get_struct_categories() allow to query the struct categories of a struct type and those defined in a module, respectively.
    • The new methods IType::is_declarative(), IFunction_definition::is_declarative(), and Definition_wrapper::is_declarative() indicate whether a type or function is declarative.
    • The interface IType_factory has been extended with methods to create, clone, compare, and dump struct categories and/or struct category lists.
    • A sixth template-like function, the so-called decl_cast operator, has been added. The new method IExpression_factory::create_decl_cast() provides a convenient way to create calls of this function definition.
    • The method IMaterial_instance::create_compiled_material() accepts the new option "target_type" on the execution context. This option behaves as if the entire material is wrapped into a decl_cast operator with the given target type.
    • The new method ICompiled_material::get_sub_expression_hash() allows to compute hash values of arbitrary sub-expressions and is not limited to predefined material slots as ICompiled_material::get_slot_hash().
    • The module builder has been extended to support struct categories: The new method IModule_builder::add_struct_category() allows to create them. The signature of the method IModule_builder::add_struct_type() has been extended with a struct_category parameter. The signature of several methods on IModule_builder has been extended with a is_declarative parameter. The old signatures are still available if MI_NEURAYLIB_DEPRECATED_15_0 is defined.

  • The methods for texture export (IMdl_impexp_api::export_canvas() and IImage_api::create_buffer_from_canvas()) and the image plugin API have been changed to use a generic options map instead of two hard-coded options. Supported options are documented at IImage_api. The old signatures are still available if MI_NEURAYLIB_DEPRECATED_15_0 is defined.

  • The new export option "exr:data_type" allows to control the data type of EXR channels.

  • The database supports now multiple scopes. For details, see the documentation for the class IScope and the methods create_scope(), get_scope(), and remove_scope() on IDatabase.

  • The new method IExpression_factory::create_temporary() allows to create temporary references.

  • The signature of IMdl_module_builder::add_function() has been extended to support temporaries. The old signature is still available if MI_NEURAYLIB_DEPRECATED_15_0 is defined.

  • The free functions set_value() and get_value() on IData support now arrays (similar to what existed already for IValue). Arrays can be specified as pointer/length pair, or as std::vector.

  • Exit codes in case of array size mismatches for the the free functions set_value() and get_value() on IValue have been changed from -3 (implementation) and -4 (documentation) to -5 for consistency with IData.

  • The methods IModule::get_function_overloads() have been updated to implement the modified overload resolution rules for MDL >= 1.9.

  • Additional performance improvements for the creation of compiled materials.

  • The recommended vcpkg version is now 5d675c7e5. This changes the recommended versions for Boost to 1.84, OpenImageIO to 2.5.8.0, and GLFW to 3.4.

  • The license texts have been split into three separate files LICENSE.md, LICENSE_IMAGES.md, and LICENSE_THIRD_PARTY.md.

  • The API reference documentation for the MDL SDK and MDL Core is now installed as part of the "install" target.

  • Added the compiler flag -flax-vector-conversions when using OpenImageIO on Linux and ARM.

  • Python Bindings:

    • Changed the recommended Python version to 3.10.
    • Improved type hints.
    • Added stub functions to keep the bindings backwards compatible.
    • Prepared for an update to Swig 4.2.1.
    • Added more tests to improve coverage.

• MDL Compiler and Backends

  • Increased default MDL version to 1.9.
  • Added support for MDL 1.9:
    • Implemented math::round_away_from_zero().
    • Implemented structure categories, declarative structures and declarative functions.
    • Adapted overload resolution to new rules.
  • Added backend option "libbsdf_flags_in_bsdf_data" to enable use of the new "flags" field in the BSDF data structures for libbsdf. The flags can be used to restrict generated sample, evaluate, pdf and auxiliary functions to only calculate reflections, transmissions or both.
  • MDL Core API: Support for declarative structs and functions (AOV support).
    • Extend the abstract syntax of MDL
      • New declaration kind mi::mdl::IDeclaration::Kind::DK_STRUCT_CATEGORY and corresponding class mi::mdl::IDeclaration_struct_category for struct category declarations.
      • New methods on mi::mdl::IDeclaration_type_struct for modifying a struct's category:
        • IQualified_name const *get_struct_category_name().
        • IDefinition const *get_struct_category_definition().
        • void set_struct_category_definition(IDefinition const *category_definition).
      • New methods on mi::mdl::IDeclaration_type_struct and mi::mdl::IDeclaration_function for the declarative flags:
        • bool is_declarative().
        • void set_declarative(bool flag).
      • New and modified methods on mi::mdl::IDeclaration_factory for handling struct categories and changes to structs and functions:
        • IDeclaration_struct_category *create_struct_category(...).
        • IDeclaration_type_struct *create_struct(bool declarative = false, ..., IQualified_name const *category_name).
        • IDeclaration_function *create_function(bool is_declarative, ...).
      • Changes to mi::mdl::IDefinition to support declarative features:
        • New definition kind DK_STRUCT_CATEGORY.
        • New definition flag DP_IS_DECLARATIVE.
        • New intrinsic DS_INTRINSIC_DAG_DECL_CAST.
        • New function IStruct_category const *get_category() to get the category of a category definition.
      • Changes to mi::mdl::IGenerated_code_dag to support declarative features:
        • New function property FP_IS_DECLARATIVE.
        • The accessor functions for functions and materials have been aligned, so each function exists. In one variant for functions and one for materials, for example: get_material_return_type() vs. get_function_return_type().
        • New accessor functions for struct categories: get_struct_category_count(), get_struct_category(), etc.
      • mi::mdl::IMaterial_instance::initialize() now has a parameter to set the target type of the material. When non-null, it specifies how the application how to view a material's fields.
      • New functions on mi::mdl::IMaterial_instance:
        • lookup_sub_expression(...) Look up a materials sub-expression by path.
        • get_sub_expression_hash(...) get the hash of the sub-expression rooted at a given path.
      • mi::mdl::IType has changed: New function mi::mdl::IType::is_declarative() to return whether a type is declarative or not.
      • New type mi::mdl::IStruct_category to reference struct categories in struct types.
      • New method IStruct_category const *mi::mdl::IType_struct::get_struct_category().
      • New method mi::mdl::IType_factory::create_struct_category() to create struct category objects.
  • MDL Core API: Others
    • Change representation of enums and structs to immutable types:
      • mi::mdl::IType_enum::get_value() and lookup() methods have changed to return a Value object instead of using out parameters.
      • mi::mdl::IType_struct::get_field() has changed to return a Field object instead of using out parameters.
      • mi::mdl::IType_factory methods create_enum() and create_struct() are changed to take all relevant information and returning immutable types. get_predefined_struct() and get_predefined_enum() also return const pointers now.
    • Moved the mi::mdl::IMaterial_instance interface out of mi::mdl::IGenerated_code_dag.
    • Use size_t for MDL AST statement, expression and definition counts/indexes.
    • Make distilling available to users of ibmdl_core.

• MDL Distiller and Baker

  • Extend distiller node types to include 4-way mixers.
  • The class mi::neuraylib::IBaker has been extended to support setting UV ranges.

• MDL Core API examples

  • Added new code generation example.

• MDL SDK examples

  • The documentation for the distilling examples is now reachable from the list of examples and topics.
  • Added a "--allowed_scatter_mode" parameter to the df_cuda, df_native, df_vulkan and dxr examples to demonstrate the BSDF flags feature.
  • MDL Example Distilling
    • Added option --uv_range.
    • Updated the example to detect whether the material being distilled and baked is using UV tile materials and if this is the case, run distilling and baking for each of the tiles.
  • MDL Example df_vulkan:
    • Added support for class compilation and implemented GLSL runtime functions for argument block reads.
    • Added command line option for outputting the generated GLSL target code to a file.
    • Changed command line option names to match other examples.
  • MDL Example DXR:
    • Renamed --gpu-debug to --gpu_debug to make it conform with other options.
    • Added colored console output for errors and warnings.
    • Changed D3D resource handling to make use of dynamic resources and add Microsoft Agility SDK as optional dependency.
    • Added the '-distill_debug' option to improve debugging of distiller plugins.
    • Added support for MDL 1.9 custom materials using the '--material_type' option.
    • Allowed to select and display AOV by specifying expressions using the '--aov' option.
    • Improved the selection of MDL expressions to generate shader code for.
    • Switched MaterialX SDK to 1.38.9.
    • Added CAMERA_POSITION scene data for a prototype implementation of MaterialX NPR nodes.

Fixed Bugs

• General

  • Python Bindings: Fixed various function binding issues.
  • Fixed get_option_count() and get_option_name() functions on IMdl_execution_context.
  • Fixed IImage::set_from_canvas() and IImage::reset_reader() to properly recognize uvtile sequences with a single tile.
  • Fixed support for search paths from "MDL_SYSTEM_PATH" and "MDL_USER_PATH" environment variables containing Unicode characters on Windows.

• MDL Compiler and Backends

  • The MDL core compiler did not compute correctly the uniform/varying property of single expression body functions, causing these to be always treated as uniform. This is fixed now. Additionally, Now the result of presets is always the same as for the underlying function.
  • Improved performance in HLSL/GLSL code generator by reducing the amount of generated code.
  • Fixed ICompiled_material opacity methods always returning OPACITY_UNKNOWN for MDL 1.5 - 1.8 materials.
  • Fixed invalid code generation for scene data function calls in environment functions. Default values are returned now.
  • Fixed failing argument block creation with MDL Core, when INVALID_REF values are provided (like texture_2d()).
  • Fixed performance regression for materials using base::transform_coordinate() or base::lookup_volume_coefficients() in some cases.
  • Fixed assignments to wrong struct members for GLSL/HLSL in rare cases.
  • Fixed 3-argument df::tint() function using shading normal instead of geometry normal to differentiate between reflection and transmission.
  • Fixed derivatives not being calculated when they were "hidden" in a call in the arguments of a user-defined function which does not use derivatives.
  • Fixed a null pointer reference when parsing crafted LLVM bitcode metadata.
  • Disabled MI_MDL_HLSL_LOAD_MODULE environment variable to avoid loading unwanted LLVM modules.
  • Fixed use of unsupported comdats for the native backend on MacOSX.
  • Fixed crash when translating color mixers with bsdf()/edf() components.
  • Fixed lost derivatives when assigning structs to each other.
  • Do not erroneously generate GLSL variable names that are GLSL keywords or restricted identifiers.
  • Fixed handling of resource sets that contain a frame number first followed by an UDIM.
  • Fixed a potential crash due to wrong reference count management in handling of module imports.
  • Fixed GLSL/HLSL code generators that sometimes generate variables in the wrong scope.
  • Do not try to resolve empty resource urls (which are invalid in MDL), and do not rewrite them into pseudo-absolute.
  • "<package>/" form, they stay unchanged (and are still not valid). This is more a cosmetic improvement.
  • Do not create the same error message more then once in some conditions.
  • Fixed some crashes in the core compiler when heavily invalid code is compiled.
  • Fixed a case where error messages were generated without file/line number.
  • Fixed compilation of constant functions that use the uniform state.
  • Improved error message 'xxx' is not a package or module name; Now it shows the wrong part only instead of the whole package.
  • Fixed GLSL/HLSL backends to generate valid code for function returning void (in MDL: empty structs or arrays of size zero).
  • Warn, if a function returns a "void-like" value (and hence might be optimized away).

• MDL Distiller and Baker

  • Transmissive_pbr target: Prevent division by zero in case of both diffuse and glossy contributions are colored black.
  • Improved support for vMaterials2 composites in the transmissive_pbr target.
  • Improved support for color_custom_curve_layer as it is used in some vMaterials (all distilling targets).
  • Reduced overestimation of diffuse contribution in treansmissive_pbr/ue4 targets for some cases.

• MDL SDK examples

  • Fixed the OptiX 7 example such that it now also works on Linux.
  • Fixed linker errors in Vulkan examples when using Vulkan SDK version 1.3.275 or newer.
  • MDL Example Traversal:
    • Fixed usage information. The example expects a module as input, not a material.
  • MDL Example DXR: Fixed glTF interaction between volume attenuation and single sided materials.

MDL SDK 2023.1.4 (373000.3036): 18 Mar 2024

ABI compatible with the MDL SDK 2023.1.4 (373000.3036) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • Added a linker script on Linux that hides all defined symbols except for the factory symbol(s).

• MDL SDK examples

  • Updated OptiX 7 example to support up to OptiX SDK 8.0.0.
  • Example AXF to MDL
    • Added support for AxF 1.9 sheen for SVBRDF representation.
    • Improved compatibility for refracting carpaint representation.
    • Improved mapping of Cook-Torrance spreads (used for non-measured BRDF fallback and flake orientation).
  • Example Execution GLSL:
    • Added enable/disable SSBO and noise function remap by command line arguments.

Fixed Bugs

• General

  • Fixed a crash if IMdl_resolved_resource_element::create_reader() returns nullptr. This might be due to an incorrect user implementation, or in legitimate cases, e.g., if the file disappeared between resolving and the query.
  • Fixed a memory leak involving the interface pointer used with the context option "user_data".

• MDL Compiler and Backends

  • Fixed inconsistent storing and reading of matrix material parameters in target argument blocks for the native backend.
  • Avoid warnings about unsupported PTX features for native backend.
  • Don't let LLVM abort at shutdown, when writing to stderr fails.
  • mdltlc: Fixed error in pattern matching of material nodes.
  • Fixed HLSL/GLSL code generation that sometimes placed temporaries into a loop body that are used outside, causing invalid code.
  • Fixed crash in the core compiler that might happen on heavily malformed MDL code.
  • Prevent errors/warnings in the core compiler without line numbers due to internal clone operations.
  • Slightly speedup compilation in multithreaded operations.
  • Do not try to resolve empty resource URLs; Note that this is still malformed MDL code.

• MDL SDK examples

  • Example df_vulkan
    • Fixed command line options to match other examples for --mdl_path / -p option.
  • Example AXF to MDL
    • Fixed re-coding of BRDF colors table (used in non-measured BRDF fallback).
  • Example Execution GLSL:
    • Fixed OpenGL 3.3 mode.

MDL SDK 2023.1.3 (373000.2208): 14 Feb 2024

ABI compatible with the MDL SDK 2023.1.3 (373000.2208) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • Update to zlib 1.3.1.

• MDL SDK examples

  • Example AXF to MDL
    • Simplified the code that constructs an instance of the spectral color constructor. This also demonstrates how to use the Argument_editor to set array arguments.

Fixed Bugs

• General

  • Fixed IMdl_factory_impl::get_db_definition_name() for entities from the ::<builtins> module.
  • Fixed export of MDL modules with uvtile and/or animated textures, where under certain conditions the first tile/frame was repeated for all tiles/frames of a particular resource set.
  • Fixed a bug that caused DB changes to become visible in concurrent transactions.
  • Fixed missing dependencies on libdl on Linux that triggered the recently added undefined symbol check on Ubuntu 20.04.

• MDL Compiler and Backends

  • Fixed indeterministic generation of rmem* variables for HLSL/GLSL.
  • Fixed invalid HLSL/GLSL code generation.

• MDL SDK examples

  • Example Distilling Target
    • Visual Studio project names for the executable and library use now different names.

MDL SDK 2023.1.2 (373000.1755): 23 Jan 2024

ABI compatible with the MDL SDK 2023.1.2 (373000.1755) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • libbsdf:
    • The roughness values computed by the generated auxiliary functions changed to contain only glossy contributions.
    • The color weights for normals and roughness in the generated auxiliary functions are now reduced by luminance instead of average.

• MDL Compiler and Backends

  • Allow more direct assignments of vectors instead of element-wise assignments for HLSL.
  • Avoid unnecessary calls to functions whose values are not actually used.
  • Avoid reading whole arrays from argument blocks or read-only data segments when providing those arrays as function parameters. This especially improves rendering performance of axf_importer materials.
  • Avoid array copies when accessing arrays provided as function parameters for HLSL/GLSL.

• MDL SDK examples

  • Add options to configure the lambda return mode and the generation of PDF and auxiliary functions to code_gen example.
  • Rename "-p" parameter of df_cuda example to "--cam" and use "-p" as short form for "--mdl_path" as in other examples.

Fixed Bugs

• General

  • nvidia::core_definitions: Fixed '--' in display names.
  • Fixed type computation of ternary operator in MDL SDK/neuray.

• MDL Compiler and Backends

  • Fixed a rare crash that could happen in an MDL module imports other modules and import the same module (diamond pattern).
  • Fixed default constructor of enum values which sometimes did not choose the first enumerator as default value.

MDL SDK 2023.1.0 (373000.1077): 14 Dec 2023

ABI compatible with the MDL SDK 2023.1.0 (373000.1077) binary release (see https://developer.nvidia.com/mdl-sdk)

Known Issues and Restrictions

• MDLE export can fail in this release with broken .mlde files that contain malformed MDL code.

Added and Changed Features

• General

  • Added rotate_around_x/y/z functions to ::nvidia::support_definitions.
  • The MDL SDK comes now with unit tests. Building of the unit tests is controlled via the cmake option MDL_ENABLE_UNIT_TESTS. Unit tests can be executed from the command line via CTest, make test, or the Visual Studio solution. Some unit tests require the idiff tool from OpenImageIO.
  • The baker uses now multiple threads.
  • The deprecated FreeImage plugin as been removed.
  • The recommended vcpkg version has been updated. It is now also recommended to install GLEW and GLFW via vcpkg. The feature flag tools for OpenImageIO is now required by some unit tests.
  • The database used by the MDL SDK supports now multiple parallel transactions. See the documentation of ITransaction for visibility and conflict resolution. This change includes adding support for ITransaction::abort(). As a consequence, if an ITransaction is released without committing or aborting, it is now automatically aborted with a warning instead of being committed with an error message.
  • The new API component ILogging_configuration has been added to the MDL SDK. The API methods IMdl_configuration::set_logger() and get_logger() have been deprecated. Use ILogging_configuration::set_receiving_logger() and ILogging_configuration::get_receiving/forwarding_logger() instead. The old methods are still available if MI_NEURAYLIB_DEPRECATED_14_1 is defined. Use ILogging_configuration::set_log_prefix(0) to prevent the forwarding logger from automatically adding the severity to the log message.
  • Additional performance improvements, in particular with a focus on creation of compiled materials.
  • The new methods IType_factory::get_mdl_type_name() and create_from_mdl_type_name() allow to serialize and deserialize types via their type names.
  • The new method IType_factory::get_mdl_module_name() returns the name of the MDL module that defines a given type. This is primarily useful for enum and struct types.
  • The method IType_array::get_deferred_size() returns now the "simple" symbol name, e.g., "N" instead of the fully qualified one.
  • The method IExpression_factory::create_direct_call() allows now to create calls to unexported functions. Note that such calls can only be used in the same module as the called function.
  • When loading textures via an MDL module, failures do no longer cause a dummy instance of ITexture to be created and IValue_texture::get_value() returns now a NULL pointer.
  • Python Bindings:
    • Added more missing interface functions to the bindings.
    • Removed all generated "declare_interface"-types.
    • Added post build step to strip unused types and functions and marked constructors invalid.
    • Fixed "error"-out-parameters by providing a ReturnCode type that can be passed by reference.
    • Added UUID comparison for interface types.
    • Updated the binding of enums which are now Python enums in the appropriate scope.
    • Extended unit tests written in Python.
    • Added a coverage report option for the unit tests written in Python.
    • Added missing and fixed existing get/set_value functions for various IData class bindings.
    • Mapping now mi::Size to Sint64 to handle -1 returns correctly.
    • Removed the IAttribute_set function from scene elements.

• MDL Compiler and Backends

  • Removed unused exception_state parameter from generated functions for non-native backends to improve performance. Needs update in renderers calling these functions.
  • Let generated functions for material expressions of base types and vector types return their values directly instead via a result buffer by setting the new backend option "lambda_return_mode" to "value". Only supported by the PTX and the LLVM-IR backend.
  • Generated auxiliary functions now separate albedo into diffuse and glossy, similar to the evaluate functions.
  • Generated auxiliary functions now also report roughness.

• MDL Distiller and Baker

  • Debugging features for mdltlc: debug_name and debug_print statements in MDLTL rules files.
  • Added mdltl unit tests.

• MDL SDK examples

  • Replaced compiler define NO_DIRECT_CALL by command line parameter --use-direct-call to make it easier to try both variants.
  • Adapted MDL SDK df_cuda and OptiX 7 examples to use the new value return mode. The MDL Core df_cuda example still uses the old default mode ("sret").
  • AxF Example:
    • Updated to Pantora 1.9.0.
    • Added search path command line options.
  • Example DXR:
    • Changed hardware sampler mode to clamp and implemented repeat by software to fix edge cases when cropping.
    • Added a MaterialX to MDL version number parameter in preparation for upcoming MaterialX releases.
    • Added options to render multiple auxiliary outputs to file in one run.

Fixed Bugs

• General

  • base.mdl:
    • Improved tangent space handling for bump maps. Noise-based bump mapping is now oriented correctly for object and world space coordinate sources.
    • Additionally, coordinate transforms change the orientation consistently now. This adds one field to base::texture_coordinate_info.
  • Added a work-around to handle user defined constants inside the code that is added using add_function() to an existing MDL module in the MDL_module_builder interface. This can only handle cases where the user defined type is either defined locally or imported using an absolute path.
  • Python Binding: Fixed proxy parameter handling of "IMdl_distiller_api::create_baker" and "ILight_profile::reset_*" functions.

• MDL Compiler and Backends

  • Fixed auto-import of enum conversion operators.
  • Fixed a case where the auto-importer was not able to import conversion operators (enum-to-int), which caused wrong prefixed constructors when exporting MDL, e.g. base::int(value).
  • Adapted data layout for PTX to match data layout used by CUDA compiler to avoid problems with misaligned data types.
  • Fixed wrong function indices set for init functions in single-init mode, when ILink_unit::add_material() is called more than once.
  • Fixed invalid CUDA prototypes returned by mi::neuraylib::ITarget_code::get_callable_function_prototype().
  • Fixed texremapu in base.mdl for GLSL resulting in undefined behaviour for negative texture coordinates.
  • Improved handling of invalid MDL code in the MDL compiler.

• MDL Distiller and Baker

  • Fixed printing of NaN, +inf and -inf constants in the mdl_distiller_cli command line utility. They are now printed as (0.0/0.0), (1.0/0.0) and (-1.0/0.0) respectively, same as in the MDL compiler and SL backends.
  • mdltlc: Fixed code generation for rules with node names.
  • mdltlc: Fixed code generation for creation of conditional expressions.

• MDL SDK examples

  • Example DXR: Fixed resource creation warnings reported with the "--gpu-debug" option on Windows 11.

MDL SDK 2023.0.6 (367100.5773): 03 Nov 2023

ABI compatible with the MDL SDK 2023.0.6 (367100.5773) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • Various performance improvements, in particular with a focus on creation of compiled materials.
  • Python Bindings:
    • Added get and set value functions to the bindings of types in mi::data and added corresponding tests.
    • Removed the IAttribute_set interface from the bindings of the IScene_element types.

• MDL Compiler and Backends

  • Optimized high-level (GLSL/HLSL) code generator to reduce code size.
  • Added new backend option "hlsl_remap_functions": This allows to remap MDL functions (including state functions) to user implemented Native HLSL implementations.

• MDL Distiller and Baker

  • Renamed mdl_distiller command line tool to mdl_distiller_cli to more clearly separate it from the distiller plugin of the same name.

Fixed Bugs

• General

  • Fixed IFactory::compare() for IString and IRef on Linux on ARM.
  • Python Bindings:
    • Fixed the binding for the ITile::get_pixel() and ITile::set_pixel() functions.
    • Mapped mi::Size to signed integer in python to allow for comparing against -1.
    • Deprecated the tuple return of functions that have an float* out parameter in C++. Now an ReturnCode object is passed in and out as Python parameter.
    • Removed unused classes and functions from the bindings.

• MDL Distiller and Baker

  • mdltlc: Fixed matching on nested attribute expressions.
  • Fixed missing enum to int conversion operator an auto-imports, which caused compilation errors in rare cases.
  • Fixed context information when compiling entities in the DAG-backend (fixes only some asserts in debug mode).
  • Fixed HLSL/GLSL code generation for access to single element compound types, like arrays of length 1 or structs with only one field.

MDL SDK 2023.0.4 (367100.4957): 05 Oct 2023

ABI compatible with the MDL SDK 2023.0.4 (367100.4957) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • Python Bindings:
    • Added binding for the (built-in) entity resolver and added unit tests.
    • Accessing functions of invalid interfaces do not crash anymore but instead throw python exceptions.
    • Added more unit tests.
    • Extend the wrapper around MDL type (Type):
      • Give access to vectors and arrays size and element type.
      • Give access to matrices size.
    • Convert low level IValues to python friendly data types:
      • Extended to give access to file path for textures, light profiles and BSDF measurements.

• MDL SDK examples

  • Example DXR:
    • Reduced the HLSL glue code and added dynamic function selection for generated shader functions.
    • Added support for backface scattering and emission.
    • Handle meters_per_scene_unit at runtime and expose the parameter to the UI.
    • MaterialX resource resolution now uses the MDL entity resolver as fallback to handle tiled resources.
    • Handle the collapse flag of the in_group annotations.
    • Improved measured BSDF runtime implementation numerically.
    • Camera pose fitting now sets near and far plane distances.
    • Added support for KHR_materials_iridescence glTF extension.
  • Example Traversal:
    • Removed the preprocessor directive that disabled the distiller option.

Fixed Bugs

• General

  • Catch memory allocation failures in the OpenImageIO plugin while exporting images.
  • Python Bindings: Fixed the mdl_distiller plugin path in the scripts for running the examples.
  • Argument expressions that are created by the API are no longer optimized by the MDL compiler, but stay "unmodified" until arguments in class compilation mode are created. This makes the generated arguments more "deterministic" for users.
  • Fixed export of uv-tile textures. Only first tile was exported.
  • Fixed export of animated textures when frame number differs from frame ID.

• MDL Compiler and Backends

  • Fixed translation of vector access with non-constant index in some cases for HLSL/GLSL.
  • Fixed bit-operations on integer fields in structs containing derivable values.
  • HLSL/GLSL: The compiler uses now name mangling on struct types instead of the very simple old connection with '_'.
  • Fixed bug that caused crashes when several MDL modules import each other within a special order.
  • Material expressions which path prefix is "geometry.displacement" are now created in the displacement context.
  • Fixed code generation for re-exported MDL entities.
  • Fixed parsing of resource sets inside container files (MDLE).
  • Fixed ownership of types in created distribution functions which could lead to crashes under certain complex conditions.
  • Fixed crashes due to "missing functions" which are requested from wrong modules, for instance state::cos().
  • Fixed printing of package name components which are MDL keywords and require quoting as Unicode identifiers.

• MDL SDK examples

  • Example DXR:
    • Fixed the UI parameter mapping for struct parameters.
    • Reviewed the UV coordinate handling and improved its documentation.
    • Added missing out of bounds check when reading NV_materials_mdl nodes.
    • Treat alpha channels in glTF textures as linear in cases where the RGB data is in sRGB color space.

MDL SDK 2023.0.2 (367100.3997): 01 Aug 2023

ABI compatible with the MDL SDK 2023.0.2 (367100.3997) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General
  • Improved installation instructions (mention VCPKG_PLATFORM_TOOLSET for Windows, add 7.5 as the currently highest supported OptiX version).

Fixed Bugs

• General

  • Fixed export of uvtile textures referenced in MDL modules.
  • Improved installation instructions for installation of thirdparty dependencies via apt-get.
  • Fixed wrong reference counts when cloning instances of IPointer and IConst_pointer via IFactory::clone() without using the option DEEP_ASSIGNMENT_OR_CLONE.

• MDL Compiler and Backends

  • All backends: Fixed code generation for material expressions with path prefix "geometry.normal".
  • Any unsupported code in GLSL/HLSL code generation will now issue an "Internal JIT backend" error. The <ERROR> marker in the generated source will remain.
  • Fixed GLSL alias type definitions inside the GLSL backend (no more "missing conversion constructor" errors).
  • Module transformer: Fixed missing constant declarations when used in some annotations in non-root modules that are inlined.
  • Module transformer: Do not loose anno::native() annotations when inlining a module.
  • Fixed MDL compiler options containing double typed values (causing wrong limits::DOUBLE_M[IN|AX]).
  • Fixed the necessary precision to print floats and doubles so it can read back without losses.
  • Fixed missing elemental constructor for locally defined structs in the DAG- representation.
  • Fixed compiler crashes for:
    • Invalid call expressions.
    • Invalid array types with a let expression as the array size.
  • Compiler now reports proper errors when a function is returned from a function.
  • Fixed PTX code generation that causes a GPU crash when the load/store instructions are generated with a wrong address space.
  • Fixed HLSL/GLSL backends generating float constants with not enough precision. In particular, the ::limits::MIN_FLOAT constant was generated wrong, causing rounding to zero later.

• MDL Distiller and Baker

  • Fixed bug in command line mdl_distiller MDL printer for ::tex module imports when textures are used in material parameter defaults.
  • Fixed mixer normalization in mdltlc for patterns with attributes.

MDL SDK 2023.0.0 (367100.2992): 03 Jun 2023

ABI compatible with the MDL SDK 2023.0.0 (367100.2992) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• MDL 1.8 Language Specification

  • Updated version to 1.8.2.
  • Removed meaningless references to a preprocessor.
  • Reduced the requirement on thin-walled materials that they should have equal transmission from both sides.
  • Added part to supported selector string components for OpenEXR.
  • Clarified that MDL comments can be nested.
  • Extend list of separators in MDL and clarify their purpose.
  • Clarified that unicode identifiers cannot be empty.
  • Added the operator function call to the precedence table of all operators.
  • Added the cast operator to the precedence table of all operators.
  • Moved operator from the set of words reserved for future use to the reserved words in use.
  • Added section for unicode identifiers.
  • Clarified that the use of variables in let-expressions is read-only.
  • Clarified that binary logical operators may or may not use short-circuit evaluation.
  • Added definition of lvalues and rvalues.
  • Removed redundant subsections that light_profile and bsdf_measurement have no members.
  • Added requirement to check for array out-of-bounds access and to return default-constructed values in this case.
  • Clarified that function parameters are lvalues in their procedural implementation bodies.
  • Added that function parameters can only be used as read-only rvalues in functions defined by an expression.
  • Added that function parameters can only be used as read-only rvalues in let-expression.
  • Changed the grammar for the let-expression from unary_expression to assignment_expressions for the expression affected by the variables. This ensures the right scope precedence, e.g., the let-expression ends at a sequence operator.
  • Removed using alias declarations. They are replaced by Unicode identifiers directly supported as package and module names.
  • Added operator function call syntax for all applicable operators.
  • Clarified that material parameters can only be used as read-only rvalues in material definitions.
  • Clarified that material parameters can only be used as read-only rvalues in let-expression.
  • Clarified that let-bound variables cannot be used in their own initializer expressions.
  • Fixed the accidentally dropped grammar production rule for the import statements in MDL files.
  • Removed the support for annotations on packages with the package.pkg file.
  • Added Unicode identifiers for package and module names.
  • Changed productions for import_path, qualified_import to allow Unicode identifiers in package and module names.
  • Added a collapsed parameter to the anno::in_group standard annotation to control the UI presentation of groups.
  • Added the standard annotation node_output_port_default and the respective enumeration type node_port_mode to control the default initialization of output ports for external shade graph nodes when they are created for MDL functions.
  • Added the standard annotation native to hint that a function or material might have a native implementation in the integration.
  • Added the standard annotation noinline to hint that a function or material should not be inlined by the compiler.
  • Added that texture spaces and their respective tangents return in volume shading their respective values at the surface entry point of the current light-transport path.
  • Added that state::texture_space and the related tangent state functions return the zero vector in case the index is out of the range of available texture spaces.
  • Clarified the exact interpolation curve for math::smoothstep and that it is undefined for a zero or reversed interpolation range.
  • Added float4x4 as supported data type for scene data lookup.
  • Removed the requirement on the scene data lookup functions to provide literal strings as arguments for the scene data names. They are now uniform strings and can be connected to uniform string parameters of a material of function definition.
  • Added a diffuse reflection BSDF modeling spherical Lambertian scatterers.
  • Added an approximative Mie VDF model for fog and cloud-like media.
  • Added a reference to the approximation used for the Mie scattering model of fog_vdf.
  • Clarified that the particle_size parameter of the new fog_vdf approximative Mie VDF model refers to the particle diameter.
  • Added custom_curve_layer and directional_factor as eligible base BSDF for the thin_film BSDF modifier.
  • Clarified that the measured_factor modifier BSDF allows reflectivities above one and it is in the responsibility of a material author to ensure energy conservation.
  • Added optional trailing commas to the productions of parameter_list, argument_list, enum_type_declaration and annotation_block.
  • Added a new Appendix G on external bindings and a section for the recommended binding of MDL functions to nodes with multiple output ports.

• General

  • base.mdl: Added an implementation of base::abbe_number_ior.
  • Improved precision of conversion of spectra to color, in particular for spectra with narrow peaks.
  • Refactored base::coordinate_projection() to reduce size of generated GPU code.
  • Added mi::neuraylib::IMdl_backend::execute_init() method to allow calling init functions in single-init mode for the native backend.
  • i18n translation:
    • Added support for the new boolean parameter to the in_group annotation (collapsed).
    • Added support for legacy "in_group$1.7" annotation.
    • i18n.exe tool:
      • Issue warning when annotation is not supported.
      • Added support for the new added boolean parameter in the in_group annotation (collapsed).
      • Added support for legacy "in_group$1.7" annotation.
  • The parameters of the MDL array constructor have been changed from "0", "1", etc. to "value0", "value1", etc. to match the MDL specification. This also affects paths to fields in the compiled material. Such paths are e.g. used by ICompiled_material::lookup_sub_expression(), IMdl_distiller_api::create_baker(), various methods on IMdl_backend and the Target_function_description struct. Hardcoded paths need to be adapted. A frequently occurring pattern is ".components.<number>." which needs to be changed to ".components.value<numner>.".
  • Removed unused enumerator value DS_SEQUENCE from mi::neuraylib::IFunction_definition::Semantics.
  • Changed BMP import of alpha channels with OpenImageIO. While the correct behavior is debatable, it restores the historical behavior of FreeImage.
  • A selector parameter has been added to the methods IImage::set_from_canvas(), and IImage_api::create_canvas_from_buffer(), and IImage_api::create_canvas_from_reader(). The old signatures are deprecated. They are still available if MI_NEURAYLIB_DEPRECATED_14_0 is defined.
  • The signatures of create_texture(), create_light_profile(), and create_bsdf_measurement() on IMdl_factory have been changed: These methods take now a IMdl_execution_context pointer as last argument instead of the optional mi::Sint32 pointer. The old signatures are deprecated. They are still available if MI_NEURAYLIB_DEPRECATED_14_0 is defined.
  • The method IImage::create_mipmaps() has been renamed to IImage::create_mipmap(). The old name is deprecated. It is still available if MI_NEURAYLIB_DEPRECATED_14_0 is defined.
  • It is now considered an error to apply the "A" selector to pixel types without alpha channel (instead of assuming a fake alpha channel with values 1.0f or 255).
  • The interface IImage_plugin has been changed to allow selector support and better plugin selection (See the API reference documentation for details):
    • The method supports_selectors() has been added.
    • The method open_for_reading() has an additional parameter for the selector string.
    • The test() method takes now a reader instead of a buffer and the file size.
  • The OpenImageIO plugin supports now also non-RGBA selectors. Right now this works only for OpenEXR textures, including OpenEXR multipart images (use the part name as selector or first selector component).
  • Full Unicode support (including code points outside of the basic multilingual planes) for MDL source code and filenames.
  • Enabled distiller support for the open source build and in various examples.
  • The minimum CMake version has been increased to 3.21 (Windows only).
  • The OpenImageIO plugin replaces the previously used FreeImage plugin. See INSTALL.md for details about the installation of OpenImageIO. All examples have been converted to use the OpenImageIO plugin instead of the FreeImage plugin.
  • The API reference documentation is now built as part of the build process if doxygen is available. This can be disabled via the option MDL_BUILD_DOCUMENTATION. GraphViz/dot (optional) is used to generate nicer inheritance diagrams.
  • Deprecated ILink_unit::add_environment(). Use ILink_unit::add_function() with ILink_unit::FEC_ENVIRONMENT as second parameter instead. The old method is still available if MI_NEURAYLIB_DEPRECATED_14_0 is defined.
  • Improved documentation for the various subclasses of IExpression, in particular IExpression_temporary and Expression_parameter.
  • The module builder supports now upgrades to MDL version 1.8, i.e., it expands namespace aliases to the corresponding Unicode identifiers, and finally removes the namespace aliases themselves.
  • Added array support to the argument editor. New overloads of Argument_editor::set_value() and get_value() allow now to set or get entire arrays in one call.
  • The OpenImageIO plugin for TIFF has been changed such that unassociated alpha mode is used for export. This avoids rounding errors and information loss for small alpha values.
  • The MDL exporter now uses TIFF instead of EXR when exporting textures with an alpha channel. This avoids rounding errors and information loss for small alpha values.
  • Various API methods related to resource loading have been fixed to properly report all error conditions. This required changing the existing error codes for those methods. The affected API methods are:
    • mi::neuraylib::IImage::reset_file()
    • mi::neuraylib::IImage::reset_reader(IReader*,...)
    • mi::neuraylib::IImage::reset_reader(IArray*,...)
    • mi::neuraylib::ILightprofile::reset_file()
    • mi::neuraylib::ILightprofile::reset_reader()
    • mi::neuraylib::IBsdf_measurement::reset_file()
    • mi::neuraylib::IBsdf_measurement::reset_reader()
    • mi::neuraylib::IVolume_data::reset_file()
    • mi::neuraylib::IVolume_data::reset_reader()
    • mi::neuraylib::IMdl_factory::create_texture()
    • mi::neuraylib::IMdl_factory::create_light_profile()
    • mi::neuraylib::IMdl_factory::create_bsdf_measurement()
    • mi::neuraylib::IImport_api::import_bsdf_data()
  • Updated jquery to version 3.6.4 and/or applied workarounds to fix a potential XSS vulnerability.
  • Replaced ITarget_code::get_body_texture_count() by ITarget_code::get_texture_is_body_resource(mi::Size) to query the information for the individual resources; same for light profiles and BSDF measurements.
  • Allow to disable all example dependencies if the SDK and core examples are disabled.
  • The finding python CMake script now falls back to the system installation if no path is specified and emits a warning in that case.
  • Changed the Clang version and existence checks so that 12.0.1 is no longer a hard requirement.
  • Disable LLVM CMake warning about host=x64.
  • IFunction_definition::get_mangled_name() was added. For definitions representing real MDL functions this returns the Itanium ABI inspired mangled name used by backends when MDL code is compiled to target code.
  • IUnit::add_function() was added, IUnit::add_environment() is now deprecated.
  • IUnit::add_function() for function definitions added by 3ds.
  • nvidia::core_definitions
    • Texture transformations changed from uniform to varying.
    • Added triplanar texturing and blending of normals.

• MDL Compiler and Backends

  • libbsdf: Added support for df::dusty_diffuse_reflection_bsdf.
  • Optimized ternary operators on df::thin_film() where the base BSDF is identical to the BSDF of the other case of the ternary.
  • Added "enable_pdf" backend option to allow disabling code generation of PDF methods for distribution functions.
  • MDL Core language support:
    • MDL 1.8 support is now complete and always enabled, no need for "mdl_next" option. Especially the following features were added:
      • scene::lookup_data_float4x4().
      • anno::native(), anno::node_output_port_default().
      • No lvalues inside let expressions and single expression functions are allowed.
      • Removed alias declarations.
    • "mdl_next" option is currently a no-op.
    • Improved some error messages.
  • Implemented normalization of df::thin_film() on the DAG.
  • libbsdf: Avoid PDF code duplication caused by nested layerer DFs.
  • Handle \u, \U, \x, and \X escapes more like C++
    • \u takes exactly 4 digits, it's an error if less are given.
    • \U takes exactly 8 digits, it's an error if less are given.
    • \x or \X without a digit is an error.
    • \x or \X with an overflow is a warning.
    • Illegal Unicode codepoints generated using \u or \U are now an error.
  • Wrong UTF-8 encodings in MDL files are now an error.

• MDL SDK examples

  • i18n, mdlx and the Python examples load now also the DDS plugin.
  • Enabled fast-math for all CUDA examples and avoid calculations on doubles.
  • Examples Shared
    • Added file IO utility to get the basename and file extension of a given path.
    • Added file IO utility to allow recursive folder creations.
    • Added file IO utility to normalize paths by removing "/../".
  • Example Code Generation
    • Added options to adapt normal and microfacet roughness.
    • Added option to compile in single-init mode.
  • Example DF CUDA
    • Switched to another random number generator to provide numbers in the range [0, 1) as expected by the generated code.
  • Example DF Native
    • Use texture results to improve performance.
    • Use single-init mode for code generation to avoid costly reevaluations of expressions.
  • Example DXR
    • Added partial support for EXT_lights_ies glTF extension.
    • Added support for MDL modules, BSDF measurements, and light profiles embedded in gltf and glb files.
    • Use single-init mode for code generation to avoid costly reevaluations of expressions.
    • Added support for the Slang shader compiler and added options to control HLSL compilation.
    • Updated DXC compiler dependency to July 2022 and made it non-optional to be able to use a new compiler interface.
    • Fixed a minor HLSL issue when compiling without "WITH_ENUM_SUPPORT".
    • Allow to use "*" as placeholder for the first material inside a given MDL module on CLI or within glTF.
    • MaterialX support improvements:
      • Allow to specify a MaterialX node to be rendered directly on CLI or within a glTF file.
      • Application side handling of resource paths defined in MaterialX.
      • Added CLI option -g to write the generated MDL module to a given path.
      • Added CLI options to match the MaterialX test renderings: constant background color, uv transformations, camera setup, and environment rotation.
    • Switched MaterialX SDK to 1.38.7.
    • MaterialX resource resolution is now handled by the example code to better reflect MDL search paths.
  • Example OptiX 7
    • Default to one sample per launch to improve experience on low-end GPUs.
    • Use real transforms instead of identity matrices.
    • Improved documentation about the required dependencies.

Fixed Bugs

• General

  • Mark BSDF and EDF data structures as 16-byte aligned to avoid a crash due to misaligned stores in generated CPU code.
  • Fixed IES parser for files with IES:LM-63-2019 standard.
  • The GLSL/HLSL backends now generate "Internal backend error" messages if some code could not be translated into the target language.
  • Added support for some previously unsupported constructs in GLSL/HLSL.

• MDL Compiler and Backends

  • MDL Core: Due to an inconsistence in the MDL Specification the MDL compiler was parsing erroneously some types of expressions after the keyword 'in' in the 'let' expressions, leading to a compiler error and resulting in that only unary type of expressions could be parsed correctly.
  • libbsdf:
    • Fixed the handling of total internal reflection for microfacet BSDFs evalation in df::scatter_transmit mode.
    • Correctly handle df::thin_film with a thickness of zero, independent of the IOR value.
  • Fixed rare crash in HLSL code generator regarding translation of load instructions.
  • Fixed missing module cache usage for non-inlined functions for link units.
  • Fixed special df::thin_film() handling for PTX backend.
  • Fixed crash for zero sized arrays in argument block layout builder.
  • Fixed inlining of functions with deferred-size arrays as parameters.
  • Fixed several bugs in the MDL compiler when compiling syntactically invalid MDL code.
  • Fixed bug in the attribute handling of the Distiller.
  • Fixed endless loop in the MDL compiler that could happen if a preset is defined with some literals under care conditions.
  • Fixed potential crash that could occur when an if and its else branch contain identical expressions.
  • Fixed garbage issued in the "called object is not a function" error message.
  • Fixed a crash when a single expression body function references an array length identifier.
  • Fixed a crash in code generation when a MDL cast<> operator was used as an argument for an select instruction.
  • Fixed non-working cast<T>(cast<S>(x)) ==> cast<T>(x) optimization.
  • Fixed missing support for {\tt rvalues} of constants in the JIT Backend.
  • Fixed optimizer does not replace constants by literal values in loop initializers.
  • Fixed DAG BE generating wrong signatures when struct insert operations are necessary.
  • Fixed handling of global scope operator, ::x may now distinct from x.
  • Printing now \U escape codes with 8 digits instead of 6 when exporting MDL.
  • Fixed a race-condition in the JIT for the native backend leading to some error messages in cases with many CPU cores.
  • Fixed opt_level 0 code generation for the PTX backend.
  • Fixed alignment of vector, matrix, array, color and struct types in argument blocks for GLSL/HLSL.
  • Improved error message when default constructing a struct which has unresolved field types.
  • Fixed auto-generated name for single init function if none was provided. Previously duplicate symbol names were generated causing linker errors when using multiple materials with the PTX backend.
  • libbsdf:
    • Fixed PDF of df::backscattering_glossy_reflection_bsdf().
    • Fixed wrong multiscatter texture for df::ward_geisler_moroder_bsdf().
    • Fixed importance sampling of df::ward_geisler_moroder_bsdf if multiscatter is on.
    • Fixed computation of diffuse part of pdf for all BSDFs with multiscatter_tint.
    • Fixed behavior of df::thin_film film with thickness 0.0.
    • Improved color correctness of df::thin_film.
  • Fixed computation of pdf in measured BSDF in native runtime.
  • Fixed handling of loops with multiple exits for GLSL/HLSL.

• MDL SDK examples

  • Fixed compilation error with Vulkan SDK 1.3.239.0 and newer.
  • Fixed pdf computation in measured BSDF for HLSL and CUDA example runtimes.
  • Examples Shared
    • Fixed out-of-bounds errors in renderer runtime.
  • Example DF Native
    • Removed memory allocations in render function to improve performance.
  • Example DXR
    • Fixed a minor HLSL issue when compiling without "WITH_ENUM_SUPPORT".
    • Fixed a crash when reloading a module after changing a MDL function signature.
    • Fixed a crash when a function that is not a material was selected for rendering.
    • Fixed a crash when having arrays of structs as material parameter.
  • Example OptiX 7
    • Fixed wrong origin used for shadow ray.
    • Fixed missing normalization and transformation of normals and tangents.

MDL SDK 2022.1.7 (363600.4887): 18 Apr 2023

ABI compatible with the MDL SDK 2022.1.7 (363600.4887) binary release (see https://developer.nvidia.com/mdl-sdk)

Fixed Bugs

• MDL Compiler and Backends
  • Fixed rare crash in HLSL code generator regarding translation of load instructions.
  • Fixed crash for zero sized arrays in argument block layout builder.
  • Several bug fixed in the MDL compiler when compiling syntactically invalid MDL code.

MDL SDK 2022.1.6 (363600.3938): 20 Mar 2023

ABI compatible with the MDL SDK 2022.1.6 (363600.3938) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • Improved performance of texture import via the OpenImageIO plugin, in particular when only the metadata is needed.

• MDL Compiler and Backends

  • Improved output messages for errors in annotations.

Fixed Bugs

• General

  • Fixed usability and layout problems in API reference documentation.
  • Added missing images in the documentation for nvidia::core_definitions.
  • Fixed layout of API reference documentation for types using the __align__(x) macro.
  • Fixed ITargetCode serialization for cases when there are multiple materials in the link unit.

• MDL Compiler and Backends

  • Fixed potential crashes in the code generator when a module name contains a '.'.
  • Fixed crash in the MDL compiler caused by invalid constant declarations.
  • Fixed compiling error in LLVM for VS2017.
  • Fixed some cases where invalid MDL source code can lead to compiler crashes.

MDL SDK 2022.1.4 (363600.2768): 14 Feb 2023

ABI compatible with the MDL SDK 2022.1.4 (363600.2768) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General
  • The priority of the FreeImage and OpenImageIO plugin has been decreased by one level, such that it is possible again to override the default plugin with a custom image plugin.

Fixed Bugs

• General

  • Fix loading of uv-tilesets/animated textures with filenames containing meta-characters of regular expressions.

• MDL Compiler and Backends

  • Fixed a crash related to parameters declared with auto type.
  • Fixed wrong compilation and/or possible crashes if a function with an assignment of an atomic type to a vector type was inlined into a material body.
  • Fixed generated code for MDL math functions that are directly mapped to HLSL/GLSL intrinsics when several overloads of the same intrinsic are used.
  • Fixed uninitialized variables in generated HLSL code in some cases when the layer and the base BSDF of a layering distribution function are the same.
  • Fixed support for modf() and sincos() for HLSL and GLSL.
  • Fixed a crash in the MDL compiler if a variant of a struct constructor is created.
  • Fixed calculation of return type for variants of auto declared functions.
  • Allow the creation of variants of the material type itself.
  • Fixed wrong optimization of the body of function variants.
  • Fixed crash when processing invalid annotations.
  • Fixed handling of struct fields with incomplete type.
  • Fixed crash when the same namespace is declared again.
  • Fixed negative results in df::fresnel_factor in numerical corner cases (libbsdf).

MDL SDK 2022.1.1 (363600.1657): 14 Dec 2022

ABI compatible with the MDL SDK 2022.1.1 (363600.1657) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General
  • Fixed a memory leak when copying canvases (regression since MDL SDK 2022).
  • Restored compatibility of base::perlin_noise_bump_texture(), base::worley_noise_bump_texture(), and base::flow_noise_bump_texture() with previous versions (differences were noticeable, in particular with strong bump factors).

MDL SDK 2022.1 (3636300.1420): 05 Dec 2022

ABI compatible with the MDL SDK 2022.1 (3636300.1420) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • This release contains a preview of a new image plugin based on OpenImageIO. It is intended to replace the FreeImage plugin in the future. As of now, the new image plugin is disabled by default and not yet supported.
  • Improved Windows implementations of mi::base::Lock and MI::THREAD::Lock to use SRWLOCK instead of CRITICAL_SECTION primitives.
  • In order to start the examples, it is no longer necessary to explicitly set the LD_LIBRARY_PATH (on Linux) or DYLD_LIBRARY_PATH (on MacOS X).
  • Allowed varying values on parameters of base::rotation_translation_scale().
  • Added the context option "export_resources_with_module_prefix" (defaults to true). If set to false, the module prefix is avoided if resources are exported as part of an exported MDL module. While the correct behavior is debatable, it restores the historical behavior of FreeImage.
  • Python Bindings
    • Added high-level Python binding module pymdl.py.
    • Generated .sh and .bat scripts to run Python examples without manually setting PATH and PYTHONPATH.

• MDL Compiler and Backends

  • Added support for Unicode identifiers to the MDL compiler (for MDL version >= 1.8).
  • Added implementations for state::geometry_tangent_u() and state_geometry_tangent_v() functions in JIT generated code. Before they were returning 0.

• MDL SDK examples

  • Example Code Generation
    • Added command line option --warn-spectrum-conv. It warns if a spectrum constructor is converted into RGB.
  • Example DXR
    • Switched MaterialX SDK to 1.38.5.
    • Added support for textures embedded in gltf and glb files.
    • Added support for a material selector to choose one of multiple materials defined in an .mtlx file.
    • Enabled the encoded names option.
    • Added support for BSDF measurement resources.
    • Added support for light profile resources.
  • MDL Browser
    • Enabled the encoded names option.
  • Example Python Bindings
    • Added an example to illustrate the use of pymdl.py for inspection.

Fixed Bugs

• General

  • Fixed conversion of spectral to color for the case that the minimum wavelength is greater than 380 nanometers.
  • Fixed artifacts in base::perlin_noise_bump_texture(), base::worley_noise_bump_texture() and base::flow_noise_bump_texture() when using small cell sizes.
  • Fixed IFunction_call::reset_argument() for cases where a default parameter referenced the directly preceding parameter.
  • Fixed IFunction_call::set_argument() to reject expressions that contain (forbidden) nested parameter references. Similarly for IFunction_definion::create_call().
  • Changed the compression level for export of PNG files back to 5 for better speed/space tradeoff.
  • Fixed IType_factory::is_compatible()} for enums (the sets of enumeration values need to be equal, not just one a subset of the other).
  • MDL plugin for Arnold
    • Added checks on shutdown to prevent crashes when the plugin is not initialized properly.

• MDL Compiler and Backends

  • Fixed crash inside the MDL core compiler when an enum value is used as the right hand side of a select expression.
  • Fixed crash in the MDL core compiler when the qualified name of an import declaration is ill formed.
  • Changed the behavior of state functions when used with an invalid texture space. Now they return always zero.

• MDL SDK examples

  • Example DXR

    • Fixed two memory leaks and added diagnostics to check for leaks in the future.
    • Fixed a rare crash due the usage of a command list from different threads.
    • Fixed handling of MaterialX absolute paths containing a ':' character.

  • Example Python Bindings

    • Fixed the debug build of the MDL Python Bindings in VS when linking against a release built of the Python interpreter.

MDL SDK 2022.0.1 (359000.3383): 21 Sept 2022

ABI compatible with the MDL SDK 2022.0.1 (359000.3383) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • The freeimage and dds plugins can now individually be excluded from the build.
  • Improved Windows building with alternative CMake generators.
  • Python bindings
    • Updated the SWIG file in order to support pymdlsdk. IFunction_definition.get_mdl_version() in Python.
    • Handle Mdl_version as output parameter. (since, removed) = mdl_func.get_mdl_version().

• MDL Compiler and Backends

  • Added compiler context option "mdl_next": Setting this option will enable preliminary features from the upcoming MDL 1.8 Version, especially:
    • Full utf8 identifiers in MDL.
    • Lifted restriction on scene access functions: The name of a scene data can be now any expression of type uniform string.

• MDL SDK examples

  • MDL Example df_vulkan
    • Added dummy implementations for unsupported runtime functions.

Fixed Bugs

• MDL Compiler and Backends

  • Fixed error message regarding wrong array type issued two times.
  • Speed up material compilation: Instantiation of a material instance is now faster due to less database queries and lesser reference counted operations.
  • Fixed module inliner handling of relative resource paths.
  • Fixed libbsdf handling of Fresnel factors.

• MDL SDK examples

  • MDL plugin for Arnold
    • Fixed edf init call (in rare cases it was accessing undefined data).
  • MDL Example df_vulkan
    • Removed alpha channel before exporting images.

MDL SDK 2022 (359000.2512): 06 Aug 2022

ABI compatible with the MDL SDK 2022.0 (359000.2512) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • Added contribution instructions and a Contributor License Agreement (CLA) form to the open source release.
  • Increased the required Python version to 3.8 as this is required by LLVM.
  • Added support for building the MDL SDK and the Examples on MacOS on ARM.
  • Added methods on IImage_api to clone canvases and tiles, to convert the pixel type and for gamma correction on tiles.
  • Disabling the "materials are functions" feature is now deprecated. To that end, the interface IMaterial_definition has been deprecated and most of the interface IMaterial_instance has been deprecated. Similarly, for the corresponding enumerators of Element_type and IMdl_evaluator_api::is_material_parameter_enabled(). See the documentation linked from IMaterial_instance for details. The interfaces with the full set of methods and the enumerators are still available if MI_NEURAYLIB_DEPRECATED_13_0 is defined.
  • Added IMdl_factory::is_valid_mdl_identifier(). Using this method avoids the need to hardcode the list of MDL keywords yourself. The example "Generate MDL identifier" makes now use of this method.
  • Both overloads of IModule::get_function_overloads() now also accept the simple name to identify the material or function definition.
  • Disabling encoded names is now deprecated. (There are no related API changes, disabling just emits a corresponding warning.)
  • Added Python bindings wrapper for IMdl_evaluator_api to support additional MDL annotations.

• MDL Compiler and Backends

  • In this version, all backends depend on LLVM now. The LLVM version was lifted from 8.0 to 12.0.1. This change is only visible, if LLVM-IR is chosen as the output format.
  • This version uses GLSL as a new target language. This new backend supports all capabilities of the already existing native, PTX, and HLSL backends, especially:
    • It can compile functions.
    • It can compile materials (by using the libbsdf).
  • The native runtime now blends between frames for animated textures.

• MDL SDK examples

  • AxF to MDL
    • New example that demonstrates how to convert X-Rite AxF file format to MDL.
  • Example DXR
    • Added support for the NV_materials_mdl glTF vendor extension.
    • Added error logging for DRED page fault data.
  • Example Execution GLSL VK
    • New example that demonstrates how to execute material subexpressions generated with the GLSL backend in Vulkan.
  • Example DF Vulkan
    • New example that demonstrates how to integrate MDL into a Vulkan based renderer with the GLSL backend.
  • Added a Python example that shows how to create an MDL expression graph and how to write the created material to disk.
  • Update MaterialX dependency to version 1.38.4.

Fixed Bugs

• General

  • Fixed handling of MDL cast operators in the SDK.
  • Fixed typos and descriptions in support_definitions.mdl.
  • Fixed issue with Python bindings and deprecated IMaterial_definition interface.
  • Fixed handling of the uniform modifier in the MDL module builder that caused correct graph constructions to fail.

• MDL Compiler and Backends

  • Fixed missing struct constructors of re-exported structure types.
  • Fixed bug in material hash calculation.

• MDL SDK examples

  • Example DXR
    • Fixed crash when loading a new scene caused by fences being signaled too early due to a race condition.

MDL SDK 2021.1.4 (349500.10153): 24 May 2022

ABI compatible with the MDL SDK 2021.1.4 (349500.10153) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• MDL Compiler and Backends

  • libbsdf: Implemented clarified df::thin_film specification - it now propagates the thin film coating parameters to its base and, in case the base is df::fresnel_layer or df::fresnel_factor, the correct coating effect on the Fresnel term is computed there.

• MDL SDK examples

  • Example DF CUDA

    • Added support for cutouts and backface bsdf/edf.

  • Example DF Native

    • Added support for derivatives.
    • Added support shadow rays inside cutouts.

Fixed Bugs

• General

  • Fixed mipmapping of 2D texture access in the native texture runtime (used with native code generation).

• MDL Compiler and Backends

  • libbsdf: Fixed numerical corner case in df::measured_factor causing broken auxiliary buffer on the native backend.
  • Removed double precision computations in libbsdf implementation, causing double type used in HLSL/native/PTX.

• MDL SDK examples

  • Example DF Native
    • Fixed wrong auxiliary outputs.

MDL SDK 2021.1.2 (349500.8766): 05 Apr 2022

ABI compatible with the MDL SDK 2021.1.2 (349500.8766) binary release (see https://developer.nvidia.com/mdl-sdk)

Fixed Bugs

• General

  • Remove wrong error message about failures to construct MDL file paths when using the module builder.

• MDL Compiler and Backends

  • Remove invalid optimization in DAG hashing.

MDL SDK 2021.1.1 (349500.8264): 18 Mar 2022

ABI compatible with the MDL SDK 2021.1.1 (349500.8264) binary release (see https://developer.nvidia.com/mdl-sdk)

Known Issues

• The version text in the MI_NEURAYLIB_PRODUCT_VERSION_STRING macro in the version.h include file contains the previous version number of "2021.1" instead of "2021.1.1".

Added and Changed Features

• Image File Format Plugins

  • Support .rgb extension for textures in the SGI file format.

Fixed Bugs

• General

  • Fixed filename extension mismatch when exporting textures referenced from MDL modules. Under certain circumstances, the texture was copied, but got a different filename extension, causing problems importing the MDL module again.
  • Fixed creation of function calls of the cast operator if the target type has frequency qualifiers. Similarly, fixed creation of function calls of the ternary operator if the argument types have frequency qualifiers.
  • Fixed handling of memory allocation failures in IImage_api::create_canvas()/create_tile() methods.
  • Also encode the simple name of function definitions. For almost all functions this does not make any change since the simple name is usually an identifier, except for a couple of operators from the builtins module.

• MDL Compiler and Backends

  • libbsdf: Fixed incorrect child normal orientation usage in df::(color_)fresnel_layer, df::(color_)custom_curve_layer and df::(color_)measured_curve_layer for backside hits.
  • HLSL backend: Fixed code generation for scene data access functions inside automatically derived expressions.

MDL SDK 2021.1 (349500.7063): 26 Jan 2022

ABI compatible with the MDL SDK 2021.1 (349500.7063) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• MDL 1.7 Language Specification

  • Removed the draft status of this document.

  • Clarified that constants can be declared locally as well, which is working since MDL 1.0.

  • Clarified that the thin_film modifier applies only to directly connected BSDFs that have a Fresnel term.

  • Clarified that the state::normal() orientation is facing outward from the volume, with thin-walled materials treated as enclosing an infinitesimally thin volume, such that both sides are facing outward and the normal always points to the observer.

• General

  • The module ::core_definitions requires now MDL 1.6 and contains a new material surface_falloff.
  • Added support for texture selectors. The selector can be queried with methods on IImage, ITexture, IVolume_data, IValue_texture, and ITarget_code. For non-volume data textures, the supported selectors are restricted to "R", "G", "B", and "A" for now.
  • Renamed IVolume_data::get_channel_name() to IVolume_data::get_selector() for consistency with IImage and ITexture. The old method is still available if MI_NEURAYLIB_DEPRECATED_12_1 is defined.
  • The signature of IMdl_factory::create_texture() has been extended to specify the selector. The old signature is deprecated and still available if MI_NEURAYLIB_DEPRECATED_12_1 is defined.
  • Added IImage_api::create_canvas_from_reader() to enable canvas creation directly from a reader (in addition to create_canvas_from_buffer()).
  • Added the methods get_pixel_type_for_channel() and extract_channel() to IImage_api, which are useful for extracting RGBA channels from existing textures.
  • Added a warning to catch some wrong implementations of IMdl_resolved_module::get_module_name().
  • Improved resource enumeration on modules. The new method IModule::get_resource() returns an IValue_resource with all details, including gamma mode and selector. The old methods returning the individual bits are deprecated and still available if MI_NEURAYLIB_DEPRECATED_12_1 is defined.
  • Added overloads of IValue_factory::create() that accept a range annotation as argument, and a type and an entire annotation block. This makes it simpler to create values that observe range annotations. Modified Definition_wrapper to make use of the latter if a parameter has no default.
  • Added IFunction_call::reset_argument() which sets an argument back to the parameter default (if present), or an value observing given range annotations, or a default-constructed value.
  • Extended IValue_factory::compare() and IExpression_factory::compare() to support floating point comparisons with an optional epsilon range.
  • The materials-are-functions feature is now enabled by default. See the documentation referenced from IMdl_configuration::set_materials_are_functions(). All examples have been updated to avoid usage of IMaterial_definition completely, and IMaterial_instance as much as possible.
  • Added an user_data option to the IMdl_execution_context, which allows the user to pass its own interface pointer around, in particular to the methods of IMdl_entity_resolver.
  • Improved performance of editing of instances of IMdl_function_call, in particular for instances with a large set of arguments. Depending on the exact circumstances, this can cut the time for a full edit cycle (create transaction, create argument editor, change argument, destroy argument editor, commit transaction) in half. An additional speedup can be obtained by making use of the additional optional argument of Argument_editor.
  • Extended IExpression_factory::compare() to support deep comparisons of call expressions. Useful to figure out whether an exporter needs to export an argument, or can rely on the corresponding default on the definition.
  • Export to EXR takes now the quality parameter into account: a value of 50 or less selects half as channel type.
  • Added create_reader() and create_writer() to IMdl_impexp_api.
  • Changed the behavior of IImage_api::adjust_gamma() to include the alpha channel. This also affects export operations (if force_default_gamma is set) and the MDL texture runtime if derivatives are enabled.
  • Added an implementation variant based on std::atomic_uint32_t to Atom32. This results in a large speedup on ARM, and on a rather small speedup on Windows.
  • Added support for animated textures:
    • The signature of various methods on IImage and ITexture has been changed. The frame index has been added as first parameter and the order of uvtile index and mipmap level has been flipped. The default arguments have been removed. The old signatures are still available if MI_NEURAYLIB_DEPRECATED_12_1 is defined. Methods to query the mapping between frame index and frame number have been added.
    • The method uvtile_marker_to_string() on IMdl_impexp_api and IExport_api has been renamed to frame_uvtile_marker_to_string(). It is still available under the old name if MI_NEURAYLIB_DEPRECATED_12_1 is defined. The method uvtile_string_to_marker() on both interfaces has been deprecated without replacement. The last component of IImage::get_original_filename() is an alternative (if available), or construct a custom string from scratch.
    • The interface IMdl_resolved_resource has been split such that it represents an array of instances of the new interface IMdl_resolved_resource_element, where each element corresponds to a texture frame (only one for non-animated textures and other resources).
    • The frame parameter has been added to various method of the runtime interfaces Texture_handler_vtable and Texture_handler_deriv_vtable. A new member m_tex_frame to support the intrinsics tex::first_frame() and tex::last_frame() has been added.
    • The examples "DF Native", "DXR", and "Execution Native" have been extended accordingly.
  • Added an overload of IMdl_factory::clone() that allows cloning of an execution context. Useful for local changes to the context options.
  • Disabled WEBP export in the FreeImage plugin due to memory access violations.
  • Changed mi::math::gamma_correction() to include the alpha channel, as it is done already in other places.

• MDL Compiler and Backends

  • Added support for libbsdf normal adaption for CUDA and native runtime. The --an option for the df_cuda and df_native examples demonstrates the feature (the dummy implementation does not change the normal, though).
  • The libbsdf implementations of the functions df::diffuse_reflection_bsdf and df::diffuse_transmission_bsdf now compensate for energy loss caused by differences of shading and geometric normal.
  • Added frame sequences resolution using frame markers in resources to the MDL core compiler.
  • Added an error message to the JIT backend that is issued if the user specifies a state module that does not contain all necessary functions.
  • Removed a redundant call to the entity resolver in the MDL core compiler when importing modules.

• MDL SDK examples

  • Examples Shared
    • All examples load now the dds plugin by default.
  • Example DF Native
    • Added support for custom texture runtime.
  • Example DXR
    • Added a new dependency to the DirectX Shader Compiler, which is optional for Windows SDK 10.0.20348.0 and later.
    • Write a memory dump file in case an application crash occurs.
    • Added support for the glTF extension "KHR_materials_emissive_strength" to the example renderer and to the MDL support module.
  • Example Python Bindings
    • Added many more interface to the Python bindings, e.g., IBaker, ICanvas, ICompiled_material, IImage_api, IMdl_Module_builder, IPlugin_configuration, and ITile, and extended the examples.

Fixed Bugs

• General

  • Fixed a bug in mdlm and i18n if the environment variable HOME is not set.
  • Fixed a bug in i18n which caused command MDL search paths other than "SYSTEM" and "USER" to get ignored.
  • Fixed IFactory::clone() when dealing with untyped arrays.
  • Fixed IMdl_backend::deserialize_target_code() such that the internal DF texture are no longer missing under certain circumstances.
  • Fixed handling of weak imports for MDL < 1.6 if an external entity resolver is set. The semantic of weak imports is now handled by the core compiler itself, an external entity resolver sees now only absolute or strictly relative module names.
  • Fixed ICompiled_material::get_hash() to take the material slots for surface.emission.mode and backface.emission.mode into account. Added enumerators SLOT_SURFACE_EMISSION_MODE and SLOT_BACKFACE_EMISSION_MODE to mi::neuraylib::Material_slot. Also added SLOT_FIRST and SLOT_LAST to support easier enumeration over all material slots.
  • Fixed a crash with default constructed BSDF measurements during MDL export/MDLE creation.
  • Fixed gamma value of pink 1x1 default textures.
  • Fixed a race condition for accessing global core JIT backend options from different threads, which could have caused overwritten options or a crash, by using the thread local core thread context options instead.

• MDL Compiler and Backends

  • Improved numerical stability in base::coordinate_projection().
  • Improved performance of math::blackbody() implementation.
  • Fixed incorrect normal flip for strongly bumped normal input (libbsdf).
  • libbsdf: Fixed incorrect flipping of the shading normal for strongly bumped normals. Note that libbsdf requires that state input shading and geometric agree on sideness (it has been forgiving with respect to that due to this bug).
  • libbsdf: Fixed a numerical issue for df::fresnel_factor() (for ior == 0).
  • libbsdf: Fixed implementation of albedo for df::tint(reflect, transmit).
  • Fixed handling of resource sets if used inside MDLE archives.
  • Fixed a crash inside the MDL core compiler if a material preset with too many arguments is compiled.

• MDL SDK examples

  • Example OptiX 7
    • Fixed normal orientation (as libbsdf needs side consistency between geometric and shading normal).

MDL SDK 2021.0.4 (344800.9767): 26 Nov 2021

ABI compatible with the MDL SDK 2021.0.4 (344800.9767) binary release (see https://developer.nvidia.com/mdl-sdk)

Fixed Bugs

• General

  • Fixed a rare case of incorrect handling of user-defined type names for structs and enums when encoded names were enabled.

• MDL Compiler and Backends

  • Fixed non-deterministic behavior with sincos calls.

MDL SDK 2021.0.3 (344800.8726): 02 Nov 2021

ABI compatible with the MDL SDK 2021.0.3 (344800.8726) binary release (see https://developer.nvidia.com/mdl-sdk)

Fixed Bugs

• MDL Compiler and Backends

  • Apply thin film only if thickness > 0.0 (libbsdf).

MDL SDK 2021.0.2 (344800.7839): 07 Oct 2021

ABI compatible with the MDL SDK 2021.0.2 (344800.7839) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• MDL SDK examples

  • Example DXR
    • Added support for various glTF extensions to the example renderer and the MDL support module. The new supported extensions are: KHR_texture_transform, KHR_materials_transmission, KHR_materials_sheen, KHR_materials_specular, KHR_materials_ior, and KHR_materials_volume.
    • Added support for state::animation_time() when the animation mode is enabled in the renderer settings.
    • Added support for volume attenuation to the renderer.
    • Update MaterialX dependency to version 1.38.1.

Fixed Bugs

• MDL Compiler and Backends

  • Fixed incorrect BSDF evaluation for df::sheen_bsdf with a transmitting "multiscatter" BSDF parameter.
  • Fixed df::thin_film implementation for the case material IOR < thin film IOR (libbsdf).
  • Fixed an internal compiler crash.
  • Creation of compiled materials fails now (instead of crashing) if some internal error condition is detected.

• MDL SDK examples

  • Example DXR
    • Fixed the UV coordinate transformations to match the glTF specification. Now the V-coordinate is simply flipped by applying v = 1.0f - v to improve UDIM support.
    • Metallic-roughness texture lookups are fixed and will now be handled strict to the glTF specification.

MDL SDK 2021.0.1 (344800.4174): 17 Aug 2021

ABI compatible with the MDL SDK 2021.0.1 (344800.4174) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • Reduced memory usage for DDS textures with subformat BC7.
  • Added a new execution context option "warning" to silence compiler warnings or to promote them to errors. See IMdl_execution_context for details.
  • Disabled warnings for deprecated MDL materials and functions by default.

• MDL Compiler and Backends

  • Reduced compilation times.
  • Updated nvidia::core_definitions with new functionality.

• MDL SDK examples

  • Example Code Generation
    • Added an option to set number of texture result slots.

Fixed Bugs

• MDL Compiler and Backends

  • Fixed handling of nvidia::baking annotations.
  • Fixed lambda results handling in single-init mode for non-HLSL.
  • Fixed uncomputed cosine in sheen_bsdf's multiscatter (was broken for a transmitting multiscatter component, libbsdf).
  • Improved numerical stability in base::coordinate_projection.
  • Fixed missing color_weighted_layer() inside the transmission analysis.
  • Fixed thin film factor implementation (libbsdf).

MDL SDK 2021 (344800.2052): 01 Jun 2021

ABI compatible with the MDL SDK 2021 (344800.2052) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• MDL 1.7 Language Specification

  • OpenVDB has been added as supported 3D texture format.
  • Minimum required versions have been added for OpenEXR, Ptex, and OpenVDB to conform to the VFX Reference Platform CY2021.
  • Supported texture selector string values have been added for each supported texture format.
  • Texture sequences with a sequence marker have been added to the definition of texture file paths.
  • The auto placeholder type specifier has been added for variable declarations and function return types.
  • The float type is required to use a 32-bit representation following the IEEE 754 single precision standard. Floating point operations for float and double may deviate but shall not interrupt nor terminate processing.
  • The int type is required to be a 32-bit signed integer in two's complement form with wrap-around operations and without exceptions.
  • The restrictions on the texture types, light profile data type, and measured BSDF data type have been removed. They can now be used for local variable types, return types, field types in user defined structures, and element type of arrays.
  • A selector string parameter has been added to the texture_2d and texture_3d constructors to support texture formats with multiple data sets and channels in a file. The anno::usage standard annotation can be used on texture parameters to pre-select selector values in an integration.
  • The operators =, ==, and != have been added for the texture types, light profile data type, and measured BSDF data type.
  • Emission has been added to the volumetric material properties.
  • The return type of a material definition can have an annotation.
  • The description of various standard annotations, like in_group and ui_order, mention their wider applicability to more elements in MDL.
  • The usage standard annotation on materials is recommended to be used on the return type and not the material definition to match the recommendation for function declarations.
  • The hyperbolic trigonometric functions cosh, sinh, and tanh have been added to the standard math library.
  • The offset functions width_offset, height_offset, and depth_offset have been added to give full access to OpenVDB bounding box information.
  • The functions first_frame and last_frame have been added to give access to the texture animation bounds.
  • The transform function grid_to_object_space has been added to give access to OpenVDB bounding box information in MDL object space.
  • A frame parameter has been added to the width, height, depth, width_offset, height_offset, depth_offset, and grid_to_object_space texture functions to select frames in texture sequences.
  • A frame parameter has been added to the texture_2d and texture_3d variants of the lookup_ltype and texel_ltype family of texture function overloads to select frames in texture sequences.
  • The uniform modifier has been removed from the tint parameter of the EDF tint modifier.
  • The VDF tint modifier has been added.
  • An overloaded variant of the directional_factor modifier has been added for EDFs.
  • The sheen_bsdf has been changed to a modifier by adding a BSDF multiscatter parameter.
  • The uniform modifier has been removed from the weight field of the edf_component and color_edf_component structures and the upper limit has been removed for the weight.
  • The color_vdf_component structure and VDF overloads for the color_normalized_mix and color_clamped_mix mixing distribution functions have been added.
  • The mix distribution functions unbounded_mix and color_unbounded_mix have been added for BSDF, EDF, and VDF.
  • An Appendix F has been added defining MDL search path conventions.

• General

  • The MDL SDK now also supports the ARM platform on Linux (aarch64-linux-gnu).
  • This release changes the naming convention used for the DB elements of modules, material definitions, and function definitions. This is necessary to avoid problems that exist with the old naming scheme when names contain certain meta-characters. See IMdl_configuration::set_encoded_names_enabled() for details. This feature is enabled by default.
  • Added the new interface IMdl_module_builder which allows incremental building of new MDL modules, as well as editing of existing MDL modules. This interface allows the definition of new struct and enum types, and of new functions and materials (including variants). It also supports references to previous entities from the same module, explicit control of frequency modifiers for parameters, and parameters without defaults. An entity can also be removed from a module (if that entity is unreferenced). The new interface can be obtained from IMdl_factory::create_module_builder(). See also the new create_module example. The method IMdl_factory::create_variants() is deprecated and still available if MI_NEURAYLIB_DEPRECATED_12_0 is defined.
  • The API can be configured to treat materials as if they are simply functions with the return type material. This means interfaces like IFunction_definition and IFunction_call can also be used for materials. See IMdl_configuration::set_materials_are_functions() for details. This feature is disabled by default. It will be enabled by default in a future release.
  • The new method IMdl_factory::uniform_analysis() allows to check the uniform property of an expression graph.
  • Improved performance for loading of MDL modules, in particular parallel loading of modules, and reloading of modules.
  • Added force_default_gamma parameter to IMdl_impexp_api::export_canvas() and IExport_api::export_canvas() to perform an automatic gamma adjustment based on the pixel type chosen for export.
  • The implementation of IFunction_definition::get_thumbnail() and IMaterial_definition::get_thumbnail() has been changed to compute the value lazily on demand.
  • The system locale used in methods of IMdl_i18n_configuration is restricted to two-letter strings to follow ISO 639-1.
  • Reduced lock scope during MDL module loading. This avoids callbacks to the entity resolver and related interfaces while holding this lock.
  • Added get_mdl_parameter_type_name(), get_return_type() and get_semantic() on IMaterial_definition for consistency with function definition. Likewise, added get_return_type() on IMaterial_instance.
  • Added IMdl_impexp_api::get_mdl_module_name() to obtain the MDL module name for a module identified by its file name.
  • Added IType_factory::clone() for type lists.
  • Made log messages from plugins available.
  • Updated recommended version numbers and use C++ 17 to meet the requirements for the VFX reference platform 2021.
  • A Python binding for the MDL SDK has been added. This binding consists of a shared library generated from the API headers using SWIG, and some additional helper functions for ease of use. In addition, there is a stub Python module to make that shared library accessible from Python code. See "Language Bindings" in the API reference for more information. Examples to demonstrate working with the Python binding are included as well.
  • In the API, the array constructor now uses --as all other function definitions-- named arguments instead of positional arguments. The previously irrelevant parameter names are now enforced to be "0", "1", and so on.
  • Added support for the "target model" compilation mode.
  • Added a context option "remove_dead_parameters" to control the removal of dead parameter in instances of ICompiled_materials. Dead parameters only survive if this options is set (enabled by default). Setting it to false produces a compatible argument block layout independent of the target material mode.
  • Reduced the verbosity of the cmake configuration output.

• MDL Compiler and Backends

  • Added support for MDL 1.7.
  • The MDL compiler warns now if a literal value would loose precision in a implicit (or explicit) conversion.
  • Improved half vector computation for custom-curve/measured-curve layering: assume refraction for non-thin-walled materials to loose less energy for non-physical glass materials constructed from separate BRDF and BTDF.
  • Protect custom-curve evaluations against cosines > 1 to avoid numerical corner cases.
  • Fixed textures with different gamma modes being reported as one texture in ITarget_code, when resource resolving was disabled.
  • Restricted several annotations to real functions (i.e. not materials): intrinsic(), throws(), const_expr(), noinline().
  • Slightly improved generated HLSL code: the HLSL optimizer can now fold constructions like vector3(a.x, a.y, a.z) into a.
  • Added support for backend option use_renderer_adapt_normal to HLSL backend.
  • Improved speed of the DAG compiler computing material hashes.
  • Added some mathematical identities for math functions in the DAG optimizer.
  • Allowed annotation ui_order() on functions and materials.
  • IMdl_backend::translate_environment() accepts now a function that returns a base::texture_return layout-compatible type.
  • MDL 1.7 support in libbsdf:
    • Unbounded EDF mix.
    • (Color-)unbounded mix for BSDFs.
    • df::sheen_bsdf's multiscatter parameter.
    • df::directional_factor for EDFs.
  • Avoid duplicate calls to common code for ternary BSDF operators and for distribution function modifiers to reduce the code size for HLSL after compilation by the DirectXShaderCompiler (libbsdf).

• Image File Format Plugins

  • The FreeImage plugin is now based on FreeImage trunk r1859 (fixes (at least) CVE-2019-12211 and CVE-2019-12212).
  • Huge speedup for loading of progressive JPEGs if only the metadata is needed.
  • Added error message with details if a DDS texture can not be loaded.
  • The dds plugin has been enhanced to support more DDS subformats, in particular BC4/5/6/7-compressed textures.

• MDL SDK examples

  • Dropped support for Kepler GPUs.
  • Example Create Module
    • New example to demonstrate the new interface IMdl_module_builder.
  • Example DF Native
    • New example to demonstrate the integration of a MDL into a renderer by using the native (CPU) backend.
  • Example Traversal
    • Added MDL search path handling.

Fixed Bugs

• General

  • Fixed IFunction_definition::create_function_call() for the special case of the array constructor: This function uses positional arguments. Ensure that user-supplied argument names are ignored, and instead "0", "1", and so on, are actually used.
  • Fixed the methods ILink_unit::add_material_path() and ILink_unit::add_material_df() if the path involves a template-like function.
  • Fixed checks for cycles in call graphs in IMaterial_instance::create_compiled_material().
  • Fixed the warnings about removed support for deprecation macros in include/mi/neuraylib/version.h to support MS Visual Studio.
  • Removed bogus error message if comparison of MDLEs returns inequality.
  • Fixed handling of resources in reloaded modules.
  • Fixed module builder such that MDL file paths are used for resources, not plain OS file names.
  • Fixed wrong handling of encoded MDL names for user-defined type names and names with suffix indicating older MDL versions.
  • Improved documentation and examples to demonstrate how to set the gamma mode, in particular when generating MDL source code via the module builder or when creating MDLEs.

• MDL Compiler and Backends

  • All error messages of recursively imported modules are now reported in the list of error messages during compilation.
  • The use of an imported user defined structure type with a nested structure type in an exported function signature has been fixed.
  • The check for incorrect varying function call attachments to uniform parameters has been fixed in the MDL SDK API.
  • The function Mdl_compiled_material::depends_on_uniform_scenedata has been fixed.
  • The custom-curve and measured-curve layering has been improved for non-thin-walled transmissive materials to reduce energy loss for some cases of modelling glass with these components.
  • The import of the ::std module in modules of lower MDL version has been fixed.
  • Avoid optimizations while adding to link units, making it impossible to select expression paths from certain distilled materials.
  • Handle correctly auto-import of types that are used only inside struct types.
  • In some rare cases array constructors of kind T[](e_1, e_2, ...) were handled incorrectly when exported into an MDLE file. Fixed now.
  • Fixed scope handling for declarations inside then/else and loop bodies.
  • Disabled tangent approximation in ::base::transform_coordinate() to fix a performance regression.
  • Fixed a potential crash when an array size constant is used in a body of a function that gets inlined in the DAG representation.
  • Fixed missing enable_if conditions inside material presets.
  • Fixed auxiliary base normals (libbsdf).
  • Fixed handling of first component in unbounded mixers (libbsdf).
  • Reduced energy loss of df::diffuse_transmission_bsdf as lower layer of df::fresnel_layer, df::custom_curve_layer, df::measured_curve_layer (libbsdf).
  • Fixed incorrect contribution of df::diffuse_transmission_bsdf (for reflection directions) and df::diffuse_reflection_bsdf (for transmission directions) for evaluation with bumped normals (libbsdf).
  • Ensure that resources cloned from another module due to a default argument are included into this module's resource table.
  • Fixed wrong function names generated for HLSL code (contained sometimes '.').
  • Fixed wrong return code when setting options for LLVM-based backends.
  • Use non-refracted transmission directions for non-Fresnel curve layering (libbsdf). This restores the behavior from 2020.1.2.
  • Fixed a crash when importing a function with texture-typed default arguments.
  • Fixed a crash when df::tint(color,edf) was used in some context.
  • Fixed computation of derivation info for builtin functions that do not have a declaration.
  • Fixed code generation not restoring import tables of modules.
  • Fixed calculation of the lambda call result index in PTX backend.
  • Fixed wrong static storage modifier for functions in HLSL.
  • Fixed generated function names for HLSL, no more "func0" etc.
  • Fixed rare code generation failure accessing the first member of a nested compound type (HLSL).
  • Fixed the pdf computation of all microfacet BSDFs in mode df::scatter_reflect_transmit to contain the selection probability (libbsdf).
  • Fixed a crash if a reserved keyword is used as a type name.
  • Fixed inlining of functions when argument expressions referenced parameters of the caller.
  • Improved error reporting on broken MDL archives and MDLEs.
  • Check upon archive creation that user-provided manifest keys form a valid identifier.
  • Fixed creation of annotations for function variants (sometimes a wrong module name was used.
  • Fixed potential crash with re-exported enable_if() annotations.

• MDL SDK examples

  • Fixed compilation with VS 2019 and CUDA 11.

MDL SDK 2020.1.2 (334300.5582): 12 Nov 2020

ABI compatible with the MDL SDK 2020.1.2 (334300.5582) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• MDL Compiler and Backends

  • A new HLSL backend option use_renderer_adapt_microfacet_roughness has been added, which allows a renderer to adapt the roughness values provided to microfacet BSDFs right before using them. The prototype of the function the renderer has to provide is float2 mdl_adapt_microfacet_roughness(Shading_state_material state, float2 roughness_uv).
  • A new execution context option ignore_noinline has been added, which allows to ignore anno::noinline() annotations, enabling inlining when creating a compiled material. Previously this happened later when generating code for distribution functions. But optimizing at this time could lead to a changed DAG which may not contain the nodes requested by the user anymore.

Fixed Bugs

• General

  • Fixed a crash in the i18n tool when accessing module annotations.

• MDL Compiler and Backends

  • Fixed wrong optimization for ternary operators selecting different vector elements in HLSL always returning the true expression.
  • Fixed wrong PTX version used for sm_86.
  • In single-init mode, don't let a requested geometry.normal expression calculate the normal again.
  • Fixed analysis of derivative variants of functions not being recognized as depending on state::normal().
  • Reduced number of texture result slots used in generated init functions.
  • Do not generate HLSL code containing min16int to ensure compatibility to Slang.
  • Fixed translation of conversion of an 8-bit to a 32-bit integer for HLSL.

MDL SDK 2020.1.1 (334300.4226): 29 Sep 2020

ABI compatible with the MDL SDK 2020.1.1 (334300.4226) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • Thumbnail paths are now resolved when they are requested. Before, the resolving was done during the module loading.
  • A new backend option eval_dag_ternary_strictly has been added, which enables strict evaluation of ternary operators (?:) on the DAG to reduce code size. By default it is enabled.
  • Improved generated code of compiled materials and lambda functions to benefit from CSE across arguments of the root node.

• MDL Compiler and Backends

  • Added single-init mode for a set of functions added to a link unit, allowing all these functions to reuse values calculated in the init function and stored in the texture results field of the state struct. To enable this mode, the first path in the target function description list given to ILink_unit::add_material() must be "init". (Note: the init function will not be marked as ITarget_code::DK_BSDF anymore.)

• MDL SDK examples

  • Examples Shared

    • Enabled CMake option for linking MSVC dynamic runtime (/MD) instead of static (/MT) by default.

  • Example Code Generation

    • Updated MaterialX support to incorporate latest changes from the MaterialX github repository (branch 1.3.8).

  • Example DXR

    • Added -e option to specify which expressions to compile.

Fixed Bugs

• MDL Compiler and Backends

  • Fixed IFunction_call::get_arguments() for the array constructor, such that it always uses "0", "1", and so on as argument names.
  • Fixed failing MDLE export if the tex::gamma_mode type is only referenced by an annotation.
  • Fixed storing matrices in texture results taking up all the space without much benefit.
  • Fixed failure to add functions to link units when the path involves template-like functions.

MDL SDK 2020.1 (334300.2228): 11 Aug 2020

ABI compatible with the MDL SDK 2020.1 (334300.2228) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• MDL 1.6 Language Specification

  • Hyperlinks have been added to the MDL Specification PDF document.

• General

  • Enabled support for MDL modules whose names contains parentheses, brackets, or commas.
  • The interface IMdl_entity_resolver has been redesigned. Support for resolving resources has been added.
  • The new interface IMdl_module_transformer allows to apply certain transformations on MDL modules.
  • Various API methods have been added in order to reduce the error-prone parsing of MDL-related names: To retrieve DB names from MDL names use get_db_module_name() and get_db_definition_name() on IMdl_factory. To retrieve parts of the MDL name from the corresponding DB element use get_mdl_package_component_count(), get_mdl_package_component_name(), and get_mdl_simple_name() on IModule; get_mdl_module_name(), get_mdl_simple_name() on IMaterial_definition; and get_mdl_module_name(), get_mdl_simple_name(), and get_mdl_parameter_type_name() on IFunction_definition and IAnnotation_definition.
  • Added a new overload of IModule::get_function_overloads() that accepts a simple name and an array of parameter type names instead of two strings. This avoids the ambiguity when parsing parentheses and commas. The old overload is deprecated and still available if MI_NEURAYLIB_DEPRECATED_11_1 is defined.
  • Improved recursive MDL module reloading: changed the traversal order from pre-order to post-order traversal, avoid flagging a module as changed if it did not change at all.
  • Improved Definition_wrapper: the creation of functions calls for template-like MDL functions requires now an actual argument list since the dummy defaults for such functions easily lead to function calls with the wrong types in the signature.
  • Added more options to control the generation of compiled materials in class compilation mode: Folding of enum and bool parameters, folding of individual parameters, folding of cutout opacity, and folding of transparent layers.
  • Added methods to retrieve the MDL version of modules, and the MDL version when a particular function or material definition was added to (and, if applicable, removed from) the MDL specification.
  • Added methods to retrieve the MDL system and user paths.
  • The legacy behavior of df::simple_glossy_bsdf can now be controlled via the interface IMdl_configuration.
  • The return type of IFunction_definition::get_body() has been changed from const IExpression_direct_call* to const IExpression*.

• MDL Compiler and Backends

  • Added support for target code serialization in the HLSL and PTX backends. See the new methods get_backend_kind(), supports_serialization(), serialize(), and get_argument_layout_count() on ITarget_code, and IMdl_backend::deserialize_target_code(). The new context option "serialize_class_instance_data" for ITarget_code::serialize() controls whether per-instance data or only per-class data is serialized.
  • Allow total internal reflection for glossy BSDFs with mode df::scatter_transmit (libbsdf).
  • When derivatives are enabled, state::position() is now derivable. Thus, the "position" field of Shading_state_material_with_derivs is now a derivative type.
  • Added "meters_per_scene_unit" field to Shading_state_material. It is used, when folding of state::meters_per_scene_unit() and state::scene_units_per_meter() has been disabled via the new IMdl_execution_context "fold_meters_per_scene_unit" option.
  • Added derivative support for matrices.
  • Added derivative support for scene data functions. Requires new texture runtime functions scene_data_lookup_deriv_float, scene_data_lookup_deriv_float2, scene_data_lookup_deriv_float3, scene_data_lookup_deriv_float4, and scene_data_lookup_deriv_color (see texture_support_cuda.h in the MDL SDK examples for the prototypes).
  • Added mi::neuraylib::ICompiled_material::depends_on_uniform_scene_data() analyzing whether any scene::data_lookup_uniform_*() functions are called by a material instance.
  • Implemented per function render state usage in ITarget_code.
  • Avoid reporting deprecated warnings, if current entity is already deprecated.

• MDL SDK examples

  • Examples Shared

    • Added utility headers for strings, enums, I/O, OS, and MDL specific tasks to be used in the examples. Updated examples to make use of the new utility headers.
    • Added GUI classes to illustrate MDL parameter editing and to unify user interfaces in examples in the future.

  • Example DXR

    • Added a new more structured user interface with various new features including the loading of scenes and environments from the menu, the replacement of materials, compilation and parameter folding options, and parameter editing in instance compilation mode.
    • Integrated the MDL browser (if built) for the replacement of a selected material.
    • Added shader caching to improve loading times (has to be enabled with option --enable_shader_cache).

  • GLTF Support

    • Added KHR_materials_clearcoat support, also in Example DXR.

  • MDL plugin for Arnold

    • Added a new example to illustrate the integration of MDL into an existing advanced CPU renderer.

  • Example Code Generation

    • Added a new example to illustrate HLSL and PTX code generation.

  • Example OptiX 7

    • Added a new example to illustrate the use MDL code as OptiX callable programs in a closest hit shader, and alternatively, how to link the MDL code directly into a per-material closest hit shader for better runtime performance.

  • Example Native

    • Added missing scene data functions of custom texture runtime.

Fixed Bugs

• General

  • Fixed documentation of Bsdf_evaluate_data structs: eval function results are output-only, not input/output.
  • Fixed compilation of materials using the array length operator.
  • Fixed crash on CentOS 7.1 when importing non-trivial MDL modules.
  • Fixed incorrect behavior during function call creation when implicit casts were enabled.

• MDL Compiler and Backends

  • Fixed file resolution during re-export of MDLE modules.
  • Fixed missing clearing of context messages when creating a link unit.
  • Fixed detection of absolute file names on Windows for MDLEs on a network share.
  • Fixed support for the read-only segment and resources inside function bodies when compiling for the native target.
  • Fixed rare crash/memory corruption than could occur on MDLE creation.
  • Fixed possible crash when inlining a function containing a for (i = ...) loop statement.
  • Fixed potential crash in the auto importer when imports of the current module are erroneous.
  • Fixed handling of suppressed warnings if notes are attached to them, previously these were attached to other messages.
  • Fixed possible crash in generating MDLE when array types are involved.
  • Fixed printing of initializers containing sequence expressions, it is T v = (a,b);, not T v = a, b;.
  • Improved AST optimizer:
    • Write optimized if conditions back.
    • Write optimized sub-expressions of binary expressions back.
    • Handle constant && x, constant || x, x && constant, x || constant.
  • Fixed folding of calls to state::meters_per_scene_unit() and state::scene_units_per_meter() in non-inlined functions.
  • Fixed wrong code generation for int to float conversions with derivatives.
  • Fixed a bug in the generated HLSL code that caused wrong calculations because loads were erroneously placed after calls modifying memory.
  • Fixed checking of valid MDL identifiers (names starting with "do" were treated as keywords, but not "do" itself).
  • Fixed overload resolution for MDL operators.
  • Fixed crash in MDL runtime when using nonexistent image files with MDL.
  • Fixed invalid translation of int to float conversion with derivatives enabled.
  • Fixed broken math::sincos() on vectors.
  • Fixed failing MDLE creation due to several missing or non-exported entities (constants, annotations).
  • Fixed failing MDLE creation if the main module was < MDL 1.6, but imported an MDL 1.6 module.
  • Fixed failing MDLE creation if non-absolute imports of ::base were used.
  • Fixed rare crashes occurring when the array constructor is used in annotations.
  • Fixed lost enumeration of BSDF data textures used by the libbsdf multiscatter.

• MDL SDK examples

  • Examples Shared
    • Fixed failing CUDA checks when minimizing application.

MDL SDK 2020.0.2 (327300.6313): 28 May 2020

ABI compatible with the MDL SDK 2020.0.2 (327300.6313) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• MDL Compiler and Backends

  • Reduced the minimum roughness threshold for microfacet BSDFs from 1e-3 to 1e-7 to make them usable for mirrors and clear glass, which is inefficient but could be required by ubershaders.
  • Added "ro_data_segment" field to Shading_state_environment ("ro_data_segment_offset" for HLSL).
  • Use "direction" for the field name of Shading_state_environment (HLSL only).
  • Made state::position() derivable.

Fixed Bugs

• MDL Compiler and Backends

  • Fixed some rare cases were resources inside MDL functions got lost.
  • Fixed crash in MDL code generators due to MDL core compiler missing some error messages when a (wrong) member selection has the same name like an enum constant.
  • Fixed rare NaN in microfacet sampling.
  • Fixed error value of ITarget_code::get_body_*() functions.
  • Fixed return value of ITarget_code::create_argument_block() when required resource callback is missing.
  • Fixed read-only data segment data not being set for native lambdas.
  • Fixed resource enumeration when compiling multiple expressions in a link unit with add_material(): ensure that resources in material bodies are enumerated first.

MDL SDK 2020.0.1 (327300.3640): 30 Mar 2020

ABI compatible with the MDL SDK 2020.0.1 (327300.3640) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • The standalone tools mdlm and i18n have been extended to support Unicode package/module names.
  • On Windows, we recommend Visual Studio 2017 or 2019. Visual Studio 2015 is still the minimum requirement.

• MDL SDK examples

  • example_dxr:
    • Enhanced dependency tracking when reloading materials to also update indirectly affected materials.
    • Only the compiled material hash is considered to detect reusable generated code which allows to reuse existing materials for structurally equal instances.
    • Skip format conversion for multi-scatter lookup data.
    • Added support for larger glTF scenes up to 2GB.
    • Improved cleanup when loading erroneous scenes.

Fixed Bugs

• General

  • Fixed handling of resources inside function bodies. Previously, these resources were not found under some conditions, causing black textures for instance.
  • Fixed too strict error checks for creation of function calls of the array index operator, the ternary operator, and the cast operator.
  • Fixed creation of variants without specifying any annotations where the annotations of the prototype were erroneously copied to the variants.
  • Fixed loading of string-based modules with absolute file paths for resources.
  • Fixed documentation of generated code interfaces: The results of eval functions are output-only, not in/out.

• MDL Compiler and Backends

  • Fixed a subtle bug in one of the code caches, which caused ignored argument changes under some complex conditions. Typically, boolean parameters were vulnerable, but could happen to parameters of any type.
  • Fixed MDL archive tool failures with Unicode package names. The MDL version of such archives is now automatically set to MDL 1.6 as lowest necessary version.
  • A bug in the resource handling was fixed that previously caused resources to be resolved and loaded more that once, possibly leading to failures if search paths had been changed in between.
  • Fixed the MDL core compiler's analysis pass. Some analysis info was computed but not annotated, causing JIT failures on functions that consists of a single expression body only.

MDL SDK 2020 (327300.2022): 22 Feb 2020

ABI compatible with the MDL SDK 2020 (327300.2022) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • A new function mi::neuraylib::IMdl_compiler::get_df_data_texture() has been added.
  • A new function mi::neuraylib::ITarget_code::get_texture_df_data_kind() has been added.
  • A new enum mi::neuraylib::Df_data_kind has been added.
  • A new flag on mi::neuraylib::IMdl_configuration instructs the MDL compiler to keep the names of let expressions and expose them as temporaries on MDL material and function definitions. This brings the structure of the material/function definition presented in the API closer to the one in the .mdl file.
  • The FreeImage plugin is now based on FreeImage 3.18.0.

• MDL Compiler and Backends

  • Support for the chiang hair_bsdf has been added to the code generator for distribution functions.

  • Changes to the internal representation of builtin MDL operators. MDL supports a variety of operators, potentially featuring an endless number of instances:

    • array index operator[]
    • array length symbol
    • ternary operator ?:

    Previously, 'local' definitions were created for every used instance of these operators in an MDL module:

    • array index operator on type T in module M: M::T@(T,int)
    • array length symbol on type T in module M: M::T.len(T)
    • ternary operator on type T in module M: M::operator?(bool,T,T)

    This representation had several drawbacks:

    • there might be one definition for the same operator in every module
    • if the operator was not used inside the source of a module, it was not created

    Especially the second point lead to several problems in the editing application. Hence, starting with the 2020.0.0 release, the internal representation was changed and operators are now represented by 'global' template-like definitions:

    • array index operator: operator[](<0>[],int)
    • array length operator: operator_len(<0>[])
    • ternary operator: operator?(bool,<0>,<0>)

    In addition, the name of the cast operator was changed from operator_cast() to operator_cast(<0>).

    Drawback: When inspecting the types of the operators definition, 'int' is returned for the template types, but this might be changed in the future by expanding the type system.

  • Support for HLSL scene data renderer runtime functions has been added. See the scene_data_* functions in mdl_renderer_runtime.hlsl MDL SDK DXR example for an example implementation.

• MDL SDK examples

  • example_dxr:
    • The texture loading pipeline has been simplified and support for UDIM textures has been added.
    • Support for scene data introduced in MDL 1.6 (prim vars) has been added.
  • example_df_cuda:
    • Support for evaluation of hair-bsdfs on an analytical cylinder has been added.

Fixed Bugs

• MDL Compiler and Backends

  • Support for multiple multiscatter textures in one target code object has been fixed.

  • Support for multiscatter textures with disabled resolve_resources backend option has been fixed.

  • Multiple HLSL code generation problems leading to non-compilable code have been fixed.

MDL SDK 2019.2 (325000.1814): 18 Dec 2019

ABI compatible with the MDL SDK 2019.2 (325000.1814) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• MDL 1.6 Language Specification

  • The file path resolution algorithm has been changed to treat weak relative paths the same as strict relative paths if the referring MDL module has an MDL version of 1.6 or higher. Furthermore, the error checks have been simplified to only protect relative paths from referring to files in other search paths.
  • The import of standard library modules has been changed in all examples to use absolute path imports.
  • An additional way of defining functions has been added using an expression instead of a procedural function body.
  • Let-expression can also be applied to functions defined using an expression.
  • The limitation has been removed that package names and module names can only be identifiers.
  • The new using alias declaration has been added to enable the use of Unicode names for module names and package names.
  • The description has been clarified that standard module names shadow only modules of the same fully qualified name while modules in subpackages can have a standard module name as their unqualified name.
  • The new scene standard library module has been added with data_isvalid, data_lookup_ltype, and data_lookup_uniform_ltype functions.
  • The new multiscatter_tint parameter has been added to all glossy BSDF models to enable energy loss compensation at higher roughness values.
  • The new df::sheen_bsdf bidirectional scattering distribution function has been added.
  • The new df::tint modifier overload has been added for the hair bidirectional scattering distribution function.
  • The new df::tint modifier overload has been added for the separate tinting of the reflective and transmissive light paths of a base BSDF.

• General

  • The new API functions
    • mi::neuraylib::IModule::reload()
    • mi::neuraylib::IModule::reload_from_string()
    • mi::neuraylib::IModule::is_valid()
    • mi::neuraylib::IMaterial_definition::is_valid()
    • mi::neuraylib::IFunction_definition::is_valid()
    • mi::neuraylib::IMaterial_instance::is_valid()
    • mi::neuraylib::IMaterial_instance::repair()
    • mi::neuraylib::IFunction_call::is_valid()
    • mi::neuraylib::IFunction_call::repair()
    • mi::neuraylib::ICompiled_material::is_valid() have been added to support reloading of MDL modules.
  • The requirements on MDL module names have been relaxed according to the MDL 1.6 Specification to allow loading of modules with Unicode names.
  • The new API functions
    • mi::neuraylib::ITarget_code::get_callable_function_df_handle_count() and
    • mi::neuraylib::ITarget_code::get_callable_function_df_handle() have been added.
  • The new API function mi::neuraylib::ITarget_code::get_texture_df_data() has been added.
  • mi::neuraylib::IMdl_compiler::load_module() can now be called from multiple threads to allow loading modules in parallel. To support custom thread blocking the new interfaces
    • mi::neuraylib::IMdl_loading_wait_handle and
    • mi::neuraylib::IMdl_loading_wait_handle_factory have been added.
  • The new API functions
    • mi::neuraylib::IMaterial_definition::get_body()
    • mi::neuraylib::IMaterial_definition::get_temporary_count()
    • mi::neuraylib::IMaterial_definition::get_temporary()
    • mi::neuraylib::IFunction_definition::get_body()
    • mi::neuraylib::IFunction_definition::get_temporary_count()
    • mi::neuraylib::IFunction_definition::get_temporary() have been added.
  • The signature of the function mi::base::ILogger::message() has been changed.
  • The API function mi::neuraylib::ITransaction::edit() has been adapted to disallow editing of database elements of type mi::neuraylib::IMaterial_definition and mi::neuraylib::IFunction_definition.
  • Support for multiple occurrence of the same annotation has been added to mi::neuraylib::Annotation_wrapper.
  • Support for deprecated features guarded by MI_NEURAYLIB_DEPRECATED_8_1 and MI_NEURAYLIB_DEPRECATED_9_1 has been removed.

• MDL Compiler and Backends

  • Support for MDL 1.6 has been added to the MDL core compiler.
  • Limited support for MDL 1.6 features has been added to the backends, in particular, the scene module is supported, but currently no code is generated for interrogating the renderer, hence always the default value is returned.
  • Support for MDL 1.6 has been added to the generated code for distribution functions, that is df::tint(reflection_tint, transmission_tint), df::sheen_bsdf(), the multiscatter_tint parameter of all BSDFs exposing this in MDL 1.6 (note that this requires that all four dimensions of Bsdf_sample_data::xi are set).
  • For evaluating parts of distribution functions that are named by handles, Bsdf_evaluate_data and Bsdf_auxiliary_data are adapted to select individual handles.
  • A new backend option df_handle_slot_mode to select how evaluate and auxiliary data is passed between the generated code and the render has been added.
  • The bsdf field of Bsdf_evaluate_data is split into bsdf_diffuse and bsdf_glossy.
  • The Bsdf_sample_data structure now requires a 4th uniform random number and returns the handle of the sampled distribution part.
  • Inlining of functions containing constant declarations into the DAG has been implemented.
  • Support for light-path-expressions in generated code for distribution functions via handles has been added.
  • Support for retrieving albedo and normal in generated code for distribution functions via generated auxiliary functions has been added.
  • The entity resolver has been sped up for built-in modules in some cases where it is clear that the module can only be read from the MDL root.
  • The memory size of the DAG representation has been slightly reduced by internalizing all DAG signatures.
  • The DAG representation now uses unsafe math operations, especially x * 0 = 0 for floating point values.

• MDL SDK examples

  • Example df_cuda has been adapted to illustrate how to evaluate parts of the distribution functions named by handles via light path expressions (LPEs).
  • All examples have been adapted to support processing of Unicode command line arguments.

Fixed Bugs

• General

  • An issue in the light profile parser has been fixed: For IESNA LM-63-2002 files the ballast-lamp value incorrectly acted as multiplier for the intensity.

• MDL Compiler and Backends

  • Several issues in the generated code for distribution functions have been fixed:
    • Bugs in the computation of the pdf and eval functions of df::ward_geisler_moroder_bsdf have been fixed.
    • Incorrect pdf computation (for sample, eval, and pdf functions) in df::ward_geisler_moroder_bsdf and df::backscattering_glossy_reflection_bsdf have been fixed.
    • Fixed a missing re-scale of pseudorandom numbers for v-cavities based masking, leading to biased results for df::scatter_reflect_transmit.
    • Only use refraction-based half vector for Fresnel-layering, not for all curve layering operations.
    • Add simple inside/outside material support based on IOR comparison to determine which IOR to override in Fresnel layering. This fixes incorrect rendering when BSDFs of type df::scatter_reflect and df::scatter_transmit are layered using df::fresnel_layer, in particular missing total internal reflection.
  • The implementation of math::isnan() and math::isfinite() has been fixed for vector types.
  • Printing of quiet NaNs for HLSL has been fixed.
  • A crash in the MDL core compiler that could occur if exported types contain errors in their default initializers has been fixed.
  • Wrong function names generated from debug::assert() calls when placed after a while loop have been fixed.
  • The name of the anno::deprecated() parameter has been fixed, it is description, not message.
  • The export of MDL modules containing relative imports has been fixed, access to the imported entities is now generated correctly.

MDL SDK 2019.1.4 (317500.5028): 27 Aug 2019

ABI compatible with the MDL SDK 2019.1.4 (317500.5028) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • A new function mi::neuraylib::IValue_texture::get_gamma() has been added.
  • The following new functions have been added to the target code generation:
    • mi::neuraylib::ITarget_code::execute_bsdf_auxiliary()
    • mi::neuraylib::ITarget_code::execute_edf_auxiliary()
  • A new function mi::neuraylib::ICompiled_material::get_surface_opacity() has been added.

• MDL Compiler and Backends

  • Code generation for auxiliary methods has been added on distribution functions for potential use in AI-denoising.
  • The spectral color constructor color(float[<N>],float[N]), math::emission_color(), and math::blackboby() are now supported in the JIT backend.
  • More optimizations regarding elemental constructors in the DAG representation have been implemented.
  • Map XOR operators on Boolean values to NOT-EQUAL in the HLSL backend to be compatible to the SLANG compiler.

• MDL SDK examples

  • The example programs example_dxr and example_df_cuda have been extended to illustrate the use of auxiliary functions.
  • A modified version of example_dxr has been added to illustrate the usage of MDL in a multi-threaded context.
  • Camera controls have been improved and new options have been added to the example program example_dxr.

Fixed Bugs

• General

  • The export of MDLE files from in-memory MDL modules has been fixed.

• MDL Compiler and Backends

  • Temporary exponential creation of DAG nodes when using derivatives has been fixed.
  • Code generation of parameters reused multiple times in a derivative context has been fixed.
  • Relative imports including "." and ".." have been fixed.
  • Duplicate global variables in generated HLSL code have been fixed.
  • Invalid code generation for HLSL for special materials has been fixed.
  • Indeterministic rare compilation errors regarding unknown functions have been fixed.
  • Indeterministic rare hangs during compilation with multiple threads have been fixed.
  • Under rare condition the code cache could return HLSL code instead of PTX and vice versa. This has been fixed.
  • The code cache that was not working under several conditions has been fixed.
  • The handling of the ?: operator on arrays inside the DAG representation has been fixed such that it computes the right name now.
  • The handling of unresolved resource paths in the target code has been fixed. Previously all resources were mapped to index 1.
  • A crash in the code generator when handling uniform matrix expressions with automatic derivatives enabled has been fixed.
  • A crash in the HLSL code generator for non-default optimization levels has been fixed.
  • A crash when adding distribution functions to a link unit after adding non- distribution functions has been fixed.

MDL SDK 2019.1.1 (317500.2554): 08 Jun 2019

ABI compatible with the MDL SDK 2019.1.1 (317500.2554) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • A new API class mi::neuraylib::IAnnotation_definition has been added.
  • The following new functions have been added:
    • mi::neuraylib::IAnnotation::get_definition()
    • mi::neuraylib::IModule::get_annotation_definition_count()
    • mi::neuraylib::IModule::get_annotation_definition(Size)
    • mi::neuraylib::IModule::get_annotation_definition(const char*)
  • Added the Boolean option fold_ternary_on_df to fold ternary operators on distribution function types in material bodies even in class compilation mode: Some uber-materials extensively use the ternary operator to switch BSDFs. This causes a lot of generated code and may not be supported by some renderers. Enabling this option will compile all arguments that control the condition of such a ternary operator in. Changing any of these arguments will then require a recompilation.

• MDL SDK examples

  • Support for the glTF extension KHR_materials_pbrSpecularGlossiness has been added to example_dxr.

Fixed Bugs

• General

  • Wrong copying of gamma values during cloning of texture values has been fixed. This especially happened for default parameters during material instantiation.
  • Fixed problem with dangling user defined types when a module is removed; previously removing a module left all its user defined types alive, preventing creating new (different) ones when the deleted module was reloaded.
  • Fixed failure when generating MDLE files that reference intensity_mode values.

• MDL Compiler and Backends

  • Fixed wrong optimization of empty do-while loops in the core compiler.
  • Fixed imports starting with . or .., which caused wrong package names before.
  • Fixed printing of float and double constants when MDL code was generated; not enough digits were used previously, causing lost precision when this code was compiled again.
  • Fixed a problem where sometimes several uninitialized variables were generated and copied around in generated HLSL code.
  • Fixed generation of useless copies, like t = t; in generated HLSL code.
  • Generated better HLSL code for vector constructor calls, like floatX(a.x, x.y, ...) => a.xy...
  • JIT compilation of functions involving sin and cos with the same argument on Mac OS has been fixed.
  • The implementation of df::color_weighted_layer has been fixed.

• MDL SDK examples

  • findGLEW has been fixed in the build script to work with CMake 3.15.

MDL SDK 2019.1 (317500.1752): 16 May 2019

ABI compatible with the MDL SDK 2019.1 (317500.1752) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• MDL 1.5 Language Specification

  • A new cast operator has been added to support assignments between structurally equivalent user defined structure types and value equivalent enumeration types to support workflows with the new MDLE format. Beginning with MDL 1.5, cast is a reserved word.
  • A new field named hair of type hair_bsdf has been added to the material type, which represents the shading model applicable for hair primitives. Beginning with MDL 1.5, hair_bsdf is a reserved word.
  • A new elemental distribution function df::chiang_hair_bsdf has been added as a hair shading model.
  • A new distribution function modifier df::measured_factor has been added to support microfacet coloring based on the angle between the half-vector and the shading normal in addition to the angle between the half-vector and the incoming ray direction.
  • Annotations have been added to annotation declarations.
  • A new standard annotation origin() has been added, which is used in the MDLE file format to reference the original declarations of refactored elements.
  • The new Appendix D -- MDLE File Format defines a new container format for a self contained MDL material or function including all of its dependencies and resources.
  • The new Appendix E -- Internationalization defines the use of XLIFF files for the localization of MDL string annotations.

• General

  • A new function IMdle_api::get_hash() has been added.
  • A new function IMdl_compiler::get_module_db_name() has been added.
  • The MDLE file format version has been bumped to 1.0.
  • MDLE files now use the new anno::origin annotation rather than a custom one.
  • A new interface mi::neuraylib::IValue_string_localized has been added.
  • A new function IType_factory::is_compatible() has been added to check if one MDL type can be cast to another.
  • A new function IExpression_factory::create_cast() has been added.
  • A new configuration interface IMdl_configuration has been added, which can be used to control the behavior of the SDK regarding the automatic insertion of casts when assigning compatible but different types to arguments of MDL instances.
  • The IMdl_discovery_api has been extended to also support discovery of resources and XLIFF files.

• MDL Compiler and Backends

  • A new backend mi::neuraylib::IMdl_compiler::MB_HLSL for HLSL code generation has been added. Please refer to the dxr example for an illustrative path tracer using it.
  • The CUDA/OptiX backend expects some new functions in the user provided renderer runtime to allow using resources unknown at compile-time via argument blocks with class compilation:
    • bool tex_texture_isvalid(Texture_handler_base const *self, tct_uint texture_idx)
    • void tex_resolution_3d(int result[3], Texture_handler_base const *self, tct_uint texture_idx)
    • bool df_light_profile_isvalid(Texture_handler_base const *self, tct_uint resource_idx)
    • tct_float df_light_profile_power(Texture_handler_base const *self, tct_uint resource_idx)
    • tct_float df_light_profile_maximum(Texture_handler_base const *self, tct_uint resource_idx)
    • bool df_bsdf_measurement_isvalid(Texture_handler_base const *self, tct_uint resource_idx) The tex_resolution_3d() function fills the width, height and depth for the given texture index into the respective result entry. The other functions are implementations for the corresponding MDL functions. See examples/mdl_sdk/shared/texture_support_cuda.h for an example implementation.
  • The compiler support for the ternary operator on material and material sub types has been improved. Several materials that caused compile errors before are now compiled flawless.
  • The MDL compiler now correctly issues an error when the called object is not a function, detecting (wrong) code like f()().
  • The compiler generated now correct MDL code when exporting functions containing a dangling if construct.
  • The compiler now (correctly) forbids the use of resource types as parameter types in annotations.
  • The PTX backend does not use global counters to generate temporary identifiers anymore, this greatly improves PTX cache hits.
  • The following MDL 1.5 features are now supported by the MDL compiler:
    • hair_bsdf() type
    • df::chiang_hair_bsdf()
    • anno::origin annotation
    • support for annotations on annotation declarations
  • The backends were upgraded to use the LLVM 7 library. This means, that the LLVM-IR backend now produces LLVM 7 IR code.
  • Allow generating code for bsdf() if "compile_constants" options is "on" (default).

• MDL SDK examples

  • A new Direct3D 12 example dxr has been added which illustrates how to use the HLSL back-end in an RTX-based real-time path tracer.
  • Support for thin-walled materials has been added to example_df_cuda.

Fixed Bugs

• General

  • Failing MDLE creation when an argument of the MDLE prototype is connected to a function which returns a user-defined type has been fixed.
  • A bug leading to different output (and therefore different hashes) when exporting the same MDLE more than once has been fixed.
  • A failure (error code -8) when creating presets from functions with user-defined return types has been fixed.
  • A failure (error code -8) when creating function presets from MDL modules with versions < 1.3 has been fixed.
  • When exporting presets from MDLE definitions or MDL definitions containing calls to MDLE definitions in their arguments, the MDLE code is now inlined into the new module, rather than resulting in invalid MDL.
  • The missing origin annotation on the main definition of an MDLE file has been added.
  • Issues resolving MDLE files on UNC file paths have been fixed.
  • Missing imports for user-defined function return types which caused MDLE creation to fail, have been added.
  • The conversion of array constructors to MDL AST expressions has been fixed.
  • The use of implicit conversion functions inside enable-if expressions is no longer forbidden.

• MDL Compiler and Backends

  • Unnecessarily slow code generation for very big output has been fixed.
  • Wrong code generation for df::bsdf_measurement_isvalid() has been fixed.
  • Creating DAG call nodes for ternary operators returning non-builtin types has been fixed.
  • For the native and PTX backends, wrong order of array elements returned by math::modf() has been fixed.
  • Native code execution on Mac has been fixed.
  • Struct member access for MDLE types containing a dot in their file path has been fixed.

MDL SDK 2019 (314800.830): 20 Feb 2019

ABI compatible with the MDL SDK 2019 (314800.830) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • This release contains a preview version of the new MDL encapsulated (MDLE) file format. Please note that MDLE files generated with this SDK version will be invalidated with the next update.
  • A new API component mi::neuraylib::IMdle_api has been added, which can be used to create MDLE files.
  • The function mi::neuraylib::IMdl_compiler::load_module() can now load MDLE files. Please note that the option bool "experimental" has to be set in the mi::neuraylib::IMdl_execution_context in order to enable support for MDL 1.5, which is needed for MDLE files.
  • The functions
    • mi::neuraylib::IMaterial_instance::is_default() and
    • mi::neuraylib::IFunction_call::is_default() have been added.
  • The standalone tool mdlm has been extended with MDLE specific commands.
  • The class mi::neuraylib::IBaker has been extended to support baking of constants of type mi::IBoolean.

• MDL SDK examples

  • A new example example_mdle has been added to illustrate the use of MDLE files.
  • The example example_df_cuda has been adapted to allow loading and rendering of MDLE files.
  • A new example example_generate_mdl_identifier that illustrates how to generate a valid mdl identifier, e.g., a module name, has been added.
  • The example mdl_browser has been extended to display MDL keywords in the info tooltip as well as above the description in list view mode.

Fixed Bugs

• General

  • A bug when translating light profile and bsdf measurement constructors from the MDL SDK API representation to the MDL Core representation has been fixed.

• MDL Compiler and Backends

  • The hash calculation for struct field access DAG calls for the PTX code cache has been fixed.
  • The handling of array parameters in class compilation has been fixed.
  • A crash when trying to fold an invalid array constructor has been fixed.
  • Missing parentheses when printing operators with the same precedence as MDL has been fixed ("a/(b*c)" was printed as "a/b*c").
  • A potential crash when generating code for distribution functions has been fixed.
  • Wrong error messages "varying call from uniform function" have been fixed, which were generated by the MDL compiler under rare circumstances for struct declarations.
  • Wrong error messages "function preset's return type must be 'uniform T' not 'T'" have been fixed, which were generated by the MDL compiler for function variants if the original function always returns a uniform result but its return type was not declared as uniform T.
  • A discrepancy between code execution on CPU and GPU for constant folding of sqrt(c) for c < 0 has been fixed. Now NaN is computed for both.

MDL SDK 2018.1.2 (312200.1281): 11 Dec 2018

ABI compatible with the MDL SDK 2018.1.2 (312200.1281) binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• MDL 1.5 Language Specification

  • A first pre-release draft of the NVIDIA Material Definition Language 1.5: Appendix E - Internationalization has been added to the documentation set.

• General

  • Support for the internationalization of MDL string annotations has been added. See the MDL 1.5 Language Specification for details.

  • A new API component mi::neuraylib::IMdl_i18n_configuration has been added, which can be used to query and change MDL internationalization settings.

  • A new standalone tool to create XLIFF files has been added. See i18n.

  • Calling mi::neuraylib::ITransaction::remove() on an MDL module will cause the module and all its definitions and other dependencies to be removed from the database as soon as it is no longer referenced by another module, material instance or function call. The actual removal is triggered by calling mi::neuraylib::ITransaction::commit().

  • A new API component mi::neuraylib::Mdl_compatibility_api has been added which allows to test archives and modules for compatibility.

  • A new standalone tool to manage MDL archives has been added. See mdlm.

  • A new API class mi::neuraylib::IMdl_execution_context intended to pass options to and receive messages from the MDL compiler has been added.

  • A new API class mi::neuraylib::IMessage intended to propagate MDL compiler and SDK messages has been added.

  • A new API function mi::neuraylib::IMdl_factory::create_execution_context has been added.

  • The signatures of the API functions

    • mi::neuraylib::IMaterial_instance::create_compiled_material()
    • mi::neuraylib::IMdl_compiler::load_module()
    • mi::neuraylib::IMdl_compiler::load_module_from_string()
    • mi::neuraylib::IMdl_compiler::export_module()
    • mi::neuraylib::IMdl_compiler::export_module_to_string()
    • mi::neuraylib::IMdl_backend::translate_environment()
    • mi::neuraylib::IMdl_backend::translate_material_expression()
    • mi::neuraylib::IMdl_backend::translate_material_df()
    • mi::neuraylib::IMdl_backend::translate_material()
    • mi::neuraylib::IMdl_backend::create_link_unit()
    • mi::neuraylib::IMdl_backend::translate_link_unit()
    • mi::neuraylib::ILink_unit::add_environment()
    • mi::neuraylib::ILink_unit::add_material_expression()
    • mi::neuraylib::ILink_unit::add_material_df()
    • mi::neuraylib::ILink_unit::add_material()

    have been changed to use the new class mi::neuraylib::IMdl_execution_context. The old versions have been deprecated and prefixed with deprecated_. They can be restored to their original names by setting the preprocessor define MI_NEURAYLIB_DEPRECATED_9_1.

  • The API functions

    • mi::neuraylib::IMdl_backend::translate_material_expression_uniform_state()
    • mi::neuraylib::IMdl_backend::translate_material_expressions()

    have been deprecated and prefixed with deprecated_. They can be restored to their original names by setting the preprocessor define MI_NEURAYLIB_DEPRECATED_9_1.

  • The utility classes

    • mi::neuraylib::Definition_wrapper and
    • mi::neuraylib::Argument_editor

    have been extended to provide member access functions.

• MDL Compiler and Backends

  • Support for automatic derivatives for 2D texture lookups has been added to the PTX, Native x86 and LLVM IR backends. This feature can be enabled via the new backend option "texture_runtime_with_derivs". Please refer to the "Example for Texture Filtering with Automatic Derivatives" documentation for more details.
  • Measured EDFs and BSDFs can now be translated to PTX, Native x86 and LLVM IR. Note that the texture runtime needs to be extended with utility functions that enable runtime access to the data.
  • Spot EDFs can now be translated to PTX, Native x86 and LLVM IR.
  • The nvidia::df module has been removed.

• MDL SDK examples

  • Support for automatic derivatives has been added to the example_execution_native,example_execution_cuda and example_df_cuda examples, which can be enabled via a command line option.
  • The example_execution_native example has been extended to allow to specify materials on the command line. It is now also possible to enable the user-defined texture runtime via a command line switch.
  • The CUDA example texture runtime has been extended with support for measured EDF and BSDF data.
  • The MDL Browser is now available as a QT QML Module which can also be integrated in non-qt based applications.
  • Initial support for class compiled parameters of type Texture, Light_profile, and Bsdf_measurement has been added to example_df_cuda. So far, it is only possible to switch between all loaded resources, new resources cannot be added.

Fixed Bugs

• General

  • An error when exporting presets where MDL definitions used in the arguments require a different version than the prototype definition has been fixed.

• MDL Compiler and Backends

  • A missing check for validity of refracted directions has been added to the generated code for the evaluation of microfacet BSDFs.
  • Incorrect code generation for math::length() with the atomic types float and double has been fixed.
  • The computation of the minimum correction pattern in the MDL compiler has been fixed.
  • The compilation of || and && inside DAG IR has been fixed.
  • Pre and post increment/decrement operators when inlined into DAG-IR have been fixed.
  • Previously missing mixed vector/atomic versions of math::min() and math::max() have been added.
  • The handling of (wrong) function references inside array constructor and init constructor has been fixed, producing better MDL compiler error messages.
  • The hash computation of lambda functions with parameters has been fixed.
  • If an absolute file URL is given for a module to be resolved AND this module exists in the module cache, the module cache is used to determine its file name. This can speed up file resolution and allows the creation of presets even if the original module is not in the module path anymore.
  • A memory leak in the JIT backend has been fixed.
  • The generated names of passed expressions for code generation have been fixed.

Known Restrictions

• When generating code for distribution functions, the parameter global_distribution on spot and measured EDF's is currently ignored and assumed to be false.

MDL SDK 2018.1.1 (307800.2890): 15 Sep 2018

ABI compatible with the MDL SDK 2018.1.1 binary release (see https://developer.nvidia.com/mdl-sdk)

Added and Changed Features

• General

  • A new API function mi::neuraylib::ILink_unit::add_material has been added to translate multiple distribution functions and expressions of a material at once.
  • A new API function mi::neuraylib::IMdl_backend::translate_material has been added to translate multiple distribution functions and expressions of a material at once.
  • A new function mi::neuraylib::ICompiled_material::get_connected_function_db_name has been added.
  • A new function IImage_api::create_mipmaps has been added.
  • A new parameter has been added to the functions mi::neuraylib::ITarget_code::execute* to allow passing in user-defined texture access functions.

• MDL Compiler and Backends

  • Diffuse EDFs can now be translated to PTX, native x86 and LLVM IR.
  • Support for passing custom texture access functions has been added to the Native backend. The built-in texture handler can be disabled via the new backend option "use_builtin_resource_handler".

• MDL SDK examples

  • The example_df_cuda example now features simple path tracing inside the sphere to enable rendering of transmitting BSDFs.
  • To allow loading of multiple materials within a module, a wildcard suffix "*" is now supported in the material name command line parameter of the example_df_cuda example.
  • The example_df_cuda has been updated to illustrate the use of the new function mi::neuraylib::ILink_unit::add_material.
  • The example_execution_native has been extended to illustrate the use of user-defined texture access functions.
  • The example_mdl_browser can now be built on Mac OS.

Fixed Bugs

• General

  • The handling of archives containing a single module has been fixed in the mi::neuraylib::IMdl_discovery_api.
  • The handling of relative search paths has been fixed in the mi::neuraylib::IMdl_discovery_api.

• MDL Compiler and Backends

  • Various fixes have been applied to the code generated for BSDF's:
    • The computation of the evaluate() function for glossy refraction has been fixed (df::simple_glossy_bsdf, df::microfacet*).
    • The sample() functions for layering and mixing now properly compute the full PDF including the non-selected components.
    • The implementation of df::color_clamped_mix() has been fixed (the PDF was incorrect and BSDFs potentially got skipped).
    • All mixers now properly clamp weights to 0..1.
    • Total internal reflection is now discarded for glossy BSDF (df::simple_glossy_bsdf, df::microfacet*) with mode df::scatter_transmit, as defined in the MDL specification.
  • Incorrect code generation for math::normalize() with the atomic types float and double has been fixed.
  • The generation of function names for array index functions for modules in packages has been fixed.
  • In rare cases, compilation of a df* function could result in undeclared parameter names (missing _param_X error), which has been fixed.
  • The compilation of MDL presets of re-exported materials has been fixed.
  • In rare cases, the original name of a preset was not computed, which has been fixed.

MDL SDK 2018.1 (307800.1800): 09 Aug 2018

• Initial open source release
• ABI compatible with the MDL SDK 2018.1 (307800.1800) binary release (see https://developer.nvidia.com/mdl-sdk)
• The following features are only available in the binary release and excluded in the source code release:
  • MDL distiller
  • Texture baking (see examples/mdl_sdk/execution_cuda for example code for texture baking)
  • GLSL compiler back end
• Added: MDL Core API, a lower-level compiler API in the MDL SDK (see src/prod/lib/mdl_core and doc/mdl_coreapi)
• Added: examples for the MDL Core API (see examples/mdl_core and doc/mdl_coreapi)