As part of a Lighting and Visualization class, as part of a 3-person team, I helped develop a simple C++-based raytracer. Using a simple JSON-based scene description languaged which could be automatically exported from Blender, it partly implemented Disney’s Principled BSDF shader to produce realistic-looking images.
It is, unfortunately, limited to fairly low polygon counts: the focus for this project was rendering accuracy, with optimization as an after-thought. Simple optimization techinques could easily result in a 100x performance improvement.
Here are some sample images:
