Final project Christian and Tom

Date: 13/Apr/2021.

The project was built upon the second practical from the course.

Installation

For successful compilation, it is necessary to have the latest version of boost (https://www.boost.org/users/download/) installed on your root directory, e.g. c:\boost. Note that the boost directory should be renamed to just 'boost', without the version numbering. We used the bunny-scene for testing.

The rest of the installation is exactly like that of Practical 2, repeated here for completeness

The skeleton uses the following dependencies: libigl, and consequently Eigen, for the representation and viewing of geometry, and libccd for collision detection. libigl viewer is using dear imGui for the menu. Everything is bundled as either submodules, or just incorporated code within the environment, and you do not have to take care of any installation details. To get the library, use:

git clone --recursive https://github.com/maniatic0/INFOMGP-Final.git

to compile the environment, go into the final folder and enter in a terminal (macOS/Linux):

mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release ../
make

In windows, you need to use cmake-gui. Pressing twice configure and then generate will generate a Visual Studio solution in which you can work. The active soution should be final_bin. Note: it only seems to work in 64-bit mode. 32-bit mode might give alignment errors.

Input

The TXT file that describes the scene, where you have several examples in thedata subfolder, is the same. For completeness, the format of the file is:

#num_objects
object1.mesh  density1  youngModulus1 PoissonRatio1 is_fixed1    COM1     q1
object2.mesh  density2  youngModulus2 PoissonRatio2 is_fixed2    COM2     q2
.....

Where:

1. objectX.mesh - an MESH file (automatically assumed in the data subfolder) describing the geometry of a tetrahedral mesh. The original coordinates are translated automatically to have $(0,0,0)$ as their COM.

2. ``density`` - the uniform density of the object. The program will automatically compute the total mass by the volume.
3. ``is_fixed`` - if the object should be immobile (fixed in space) or not.
4. ``COM`` - the initial position in the world where the object would be translated to. That means, where the COM is at time $t=0$.
5. ``q`` - the initial orientation of the object, expressed as a quaternion that rotates the geometry to $q*object*q^{-1}$ at time $t=0$.
6. ``youngModulus1`` and ``PoissonRatio1`` should be ignored for now; we will use them in the $3^{rd}$ practical.

The user attachment constraints file, given as the third argument, has to have the following format:

#num_constraints
mesh_i1 vertex_i1 mesh_j1 vertex_j1 
mesh_i2 vertex_i2 mesh_j2 vertex_j2 
.....

Each row is a constraint attaching the vertex vertex_i1 of mesh mesh_i1 to vertex_j2 of mesh mesh_j2. Every row is an independent such constraint. You can find TXT files in the data folder with similar name to the scenes they accompany. You can of course write new ones. Note that the meshes start indexing from $1$---if you put a constraint to mesh $0$, it will get attached to the platform (which should still work).

Note

Our algorithm required some functionality from cgal. This library requires the use of boost however. Because we did not want our project to depend on boost, we have spend a lot of time trying to find an alternative. Unfortunately, we were unable to find it.

We also ran into a problem where the executable was unable to find a certain dll. This should be fixed now by some lines we added in the cmake file.

Lastly, the code is a bit slow and the 'impact plane' projection is not quite accurate. In the end, we had too little time to fix these issues.