I wanted to understand how Cycles works, so I coded my own GPU Path Tracer from scratch in C#. Here is my final render!
https://reddit.com/link/1tflvbe/video/ajy6qm93do1h1/player
Hey r/blender,
I've spent countless hours watching Cycles do its magic, so I decided to learn the math under the hood and write my own GPU Path Tracer from scratch in C#!
It runs directly on my Nvidia GTX 1050 using ILGPU to compile C# into CUDA. Here is a 3-second camera flyby I just rendered!
Tech Stack & Features:
- GPU-Accelerated: No game engine, just a pure C# console app running on CUDA via ILGPU.
- PBR Materials: Rough metals, glass with refraction (including hollow glass), and shiny plastic (using Schlick's approximation for clearcoat Fresnel).
- Physical Camera: Real Depth of Field (adjustable aperture/focus distance) and lens bokeh.
- Lighting: Physical sphere sun casting soft shadows, combined with global illumination.
- Post-Processing: ACES Tonemapping, Gamma 2.2, and a custom GPU Bilateral Denoise Filter to clean up fireflies while keeping edges crisp.
I literally started with a flat, solid red circle on a blue screen. Seeing it evolve into normal mapping, moving it to the GPU, and finally watching ACES and the denoiser work together has been an incredible coding journey.
Since I am only 15 and still learning, I'd love to hear your feedback! How close does this look to Cycles in your opinion? What features should I code next?
Code is fully version-controlled on Git, and I'll keep optimizing it!
https://github.com/noackjona-hash/GPU-Path-Tracer-from-scratch-in-C-