https://github.com/aras-p/toypathtracer
Toy path tracer for my own learning purposes (CPU/GPU, C++/C#, Win/Mac/Wasm, DX11/Metal, also Unity)
https://github.com/aras-p/toypathtracer
burst cpp csharp gpu metal path-tracing unity
Last synced: 6 months ago
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Toy path tracer for my own learning purposes (CPU/GPU, C++/C#, Win/Mac/Wasm, DX11/Metal, also Unity)
- Host: GitHub
- URL: https://github.com/aras-p/toypathtracer
- Owner: aras-p
- License: unlicense
- Created: 2018-03-23T13:53:26.000Z (over 7 years ago)
- Default Branch: main
- Last Pushed: 2025-04-12T05:53:35.000Z (7 months ago)
- Last Synced: 2025-05-14T23:06:47.051Z (6 months ago)
- Topics: burst, cpp, csharp, gpu, metal, path-tracing, unity
- Language: C++
- Homepage: https://aras-p.info/blog/2018/03/28/Daily-Pathtracer-Part-0-Intro/
- Size: 491 KB
- Stars: 1,096
- Watchers: 48
- Forks: 114
- Open Issues: 2
-
Metadata Files:
- Readme: readme.md
- License: license.md
Awesome Lists containing this project
README
# Toy Path Tracer [](https://github.com/aras-p/ToyPathTracer/actions)
Toy path tracer I did in 2018 for my own learning purposes. Somewhat based on Peter Shirley's
[Ray Tracing in One Weekend](https://raytracing.github.io/) minibook (highly recommended!), and on Kevin Beason's
[smallpt](http://www.kevinbeason.com/smallpt/).
I decided to write blog posts about things I discover as I do this:
* [Part 0: Intro](http://aras-p.info/blog/2018/03/28/Daily-Pathtracer-Part-0-Intro/)
* [Part 1: Initial C++ and walkthrough](http://aras-p.info/blog/2018/03/28/Daily-Pathtracer-Part-1-Initial-C--/)
* [Part 2: Fix stupid performance issue](http://aras-p.info/blog/2018/03/28/Daily-Pathtracer-Part-2-Fix-Stupid/)
* [Part 3: C#, Unity and Burst](http://aras-p.info/blog/2018/03/28/Daily-Pathtracer-Part-3-CSharp-Unity-Burst/)
* [Part 4: Correctness fixes and Mitsuba](http://aras-p.info/blog/2018/03/31/Daily-Pathtracer-Part-4-Fixes--Mitsuba/)
* [Part 5: simple GPU version via Metal](http://aras-p.info/blog/2018/04/03/Daily-Pathtracer-Part-5-Metal-GPU/)
* [Part 6: simple GPU version via D3D11](http://aras-p.info/blog/2018/04/04/Daily-Pathtracer-Part-6-D3D11-GPU/)
* [Part 7: initial C++ SIMD & SoA](http://aras-p.info/blog/2018/04/10/Daily-Pathtracer-Part-7-Initial-SIMD/)
* [Part 8: SSE SIMD for HitSpheres](http://aras-p.info/blog/2018/04/11/Daily-Pathtracer-8-SSE-HitSpheres/)
* [Part 9: ryg optimizes my code](http://aras-p.info/blog/2018/04/13/Daily-Pathtracer-9-A-wild-ryg-appears/)
* [Part 10: Update all implementations to match](http://aras-p.info/blog/2018/04/16/Daily-Pathtracer-10-Update-CsharpGPU/)
* [Part 11: Buffer-oriented approach on CPU](http://aras-p.info/blog/2018/04/19/Daily-Pathtracer-11-Buffer-Oriented/)
* [Part 12: Buffer-oriented approach on GPU D3D11](http://aras-p.info/blog/2018/04/25/Daily-Pathtracer-12-GPU-Buffer-Oriented-D3D11/)
* [Part 13: GPU thread group data optimization](http://aras-p.info/blog/2018/05/28/Pathtracer-13-GPU-threadgroup-memory-is-useful/)
* [Part 14: Make it run on iOS](http://aras-p.info/blog/2018/05/30/Pathtracer-14-iOS/)
* [Part 15: A bunch of path tracing links](http://aras-p.info/blog/2018/08/01/Pathtracer-15-Pause--Links/)
* [Part 16: Unity C# Burst optimization](http://aras-p.info/blog/2018/10/29/Pathtracer-16-Burst-SIMD-Optimization/)
* [Part 17: WebAssembly](http://aras-p.info/blog/2018/11/16/Pathtracer-17-WebAssembly/)
Note: it can only do spheres, no bounding volume hierachy of any sorts, a lot of stuff hardcoded.
Performance numbers in Mray/s on a scene with ~50 spheres and two light sources, running on the CPU:
| Language | Approach | Ryzen 5950 | AMD TR1950 | MBP 2021 | MBP 2018 | MBA 2020 | iPhone 11 | iPhone X | iPhone SE |
|:--- |:--- | ---:| ---:| ---:| ---:| ---:| ---:| ---:| ---:|
| C++ | SIMD Intrinsics | 281.0 | 187.0 | 105.4 | 74.0 | 32.3 | 26.4 | 12.9 | 8.5 |
| | Scalar | 141.2 | 100.0 | 84.8 | 35.7 | | 15.9 |
| | WebAssembly (no threads, no SIMD) | 8.4 | 5.0 | 8.1 | | | 5.6 |
| C# | Unity Burst "manual" SIMD | 227.2 | 133.0 | 103.7 | 60.0 | | 29.7 |
| | Unity Burst | | 82.0 | | 36.0 | | |
| | Unity (Editor) | 6.5 | | 3.4 | | | |
| | Unity (player Mono) | 6.7 | | 3.5 | | | |
| | Unity (player IL2CPP) | 39.1 | | 63.8 | | | 17.2 |
| | .NET 6.0 | 91.5 | 53.0 | 40.9 | |
| | .NET Core 2.0 | 86.1 | 53.0 | | 23.6 |
| | Mono --llvm | | | 35.1 | 22.0 |
| | Mono | 23.6 | | 3.6 | 6.1 |
More detailed specs of the machines above are:
* `Ryzen 5950`: AMD Ryzen 5950X (3.4GHz, 16c/32t), Visual Studio 2022.
* `AMD TR1950`: AMD ThreadRipper 1950X (3.4GHz, SMT disabled - 16c/16t), Visual Studio 2017.
* `MBP 2021`: Apple MacBook Pro M1 Max (8+2 cores), Xcode 13.2.
* `MBP 2018`: Apple MacBook Pro mid-2018 (Core i9 2.9GHz, 6c/12t).
* `MBA 2020`: Apple MacBook Air 2020 (Core i7 1.2GHz, 4c/8t).
* `iPhone 11`: A13 chip.
* `iPhone X`: A11 chip.
* `iPhone SE`: A9 chip.
Software versions:
* Unity 2021.3.16. Burst 1.6.6 (safety checks off). C# testing in editor, Release mode.
* Mono 6.12.
And on the GPU, via a compute shader in D3D11 or Metal depending on the platform:
| GPU | Perf |
|:--- | ---:|
| D3D11 | |
| GeForce RTX 3080Ti | 3920 |
| GeForce GTX 1080Ti | 1854 |
| Metal | |
| MBP 2024 (M4 Max) | 1680 |
| MBP 2021 (M1 Max) | 1065 |
| MBP 2018 (Radeon Pro 560X) | 246 |
| MBA 2020 (Iris Plus) | 201 |
| iPhone 11 Pro (A13) | 80 |
| iPhone X (A11) | 46 |
| iPhone SE (A9) | 20 |
A lot of stuff in the implementation is *totally* suboptimal or using the tech in a "wrong" way.
I know it's just a simple toy, ok :)
### Building
* C++ projects:
* Windows (Visual Studio 2017) in `Cpp/Windows/ToyPathTracer.sln`. DX11 Win32 app that displays result as a fullscreen CPU-updated or GPU-rendered texture.
Pressing G toggles between GPU and CPU tracing, A toggles animation, P toggles progressive accumulation.
* Mac/iOS (Xcode 10) in `Cpp/Apple/ToyPathTracer.xcodeproj`. Metal app that displays result as a fullscreen CPU-updated or GPU-rendered texture.
Pressing G toggles between GPU and CPU tracing, A toggles animation, P toggles progressive accumulation.
Should work on both Mac (`Test Mac` target) and iOS (`Test iOS` target).
* WebAssembly in `Cpp/Emscripten/build.sh`. CPU, single threaded, no SIMD.
* C# project in `Cs/TestCs.sln`. A command line app that renders some frames and dumps out final TGA screenshot at the end.
* Unity project in `Unity`. I used Unity 2021.3.16.