Lux is a work in progress tail-recursive raytracer written in Scheme. It is able to model diffuse, mirror, and glass spheres. It is partially based off of smallpt and uses techniques from the book Ray Tracing in One Weekend.
The 500x500 render below won 1st place in the heavyweight division of the Fall 2017 CS61A Scheme Art Contest at UC Berkeley. This project uses the CS61A implementation of Turtle graphics.
We started with a naive ray tracing implementation. Running the initial version of the program through a Python3 scheme interpreter, we rendered a 20x20 image of the Cornell box using 4 samples/pixel in around five minutes:
This is a 200x200 image of the same scene at 4 samples/pixel, rendered in ~7-8 hours:
It became apparent that rendering images at higher resolutions with less noise would take far too long. After exploring a few optimization options, we found that PyPy could run the Python interpreter at far greater efficiency. Using PyPy3, this 100x100 image of the Cornell box at 10 samples/pixel took around 25 minutes to render:
Here is a 300x300 image at 4 samples/pixel:
Finally, with adjusted colors, scene arrangement, and an additional diffuse surface, our 500x500 image at 500 samples/pixel:
