3D Fractals
Here, I implemented a CPU-based ray-tracer in C++, which simulates paths of light through space as they collide with the computed fractal geometry. For 3D fractals, whose shape is complicated and chaotic, these light paths need to take lots of very small steps to avoid skipping right through parts of the fractal. These small step sizes make this kind of ray tracing computationally expensive, especially when done many times per pixel, for a million pixels, just for a single image. Multi-threading can reduce the time significantly, though the rendering time of these fractals ranged from 2 minutes to 30 minutes.
The code for this is old and horrible and I shall not be releasing it. Sorry.
Please see my work on path tracing for newer 3D fractals.