pythagoras_tree.sf

#!/usr/bin/ruby

#
## https://rosettacode.org/wiki/Pythagoras_tree
#

require('Imager')

func tree(img, x1, y1, x2, y2, depth) {

    depth <= 0 && return()

    var dx = (x2 - x1)
    var dy = (y1 - y2)

    var x3 = (x2 - dy)
    var y3 = (y2 - dx)
    var x4 = (x1 - dy)
    var y4 = (y1 - dx)
    var x5 = (x4 + 0.5*(dx - dy))
    var y5 = (y4 - 0.5*(dx + dy))

    # square
    img.polygon(
        points => [
            [x1, y1],
            [x2, y2],
            [x3, y3],
            [x4, y4],
        ],
        color => [0, 255/depth, 0],
    )

    # triangle
    img.polygon(
        points => [
            [x3, y3],
            [x4, y4],
            [x5, y5],
        ],
        color => [0, 255/depth, 0],
    )

    tree(img, x4, y4, x5, y5, depth - 1)
    tree(img, x5, y5, x3, y3, depth - 1)
}

var (width=1920, height=1080)
var img = %s<Imager>.new(xsize => width, ysize => height)
img.box(filled => 1, color => 'white')
tree(img, width/2.3, height, width/1.8, height, 10)
img.write(file => 'pythagoras_tree.png')