Show HN: a Rust ray tracer that runs on any GPU – even in the browser

Posted by tchauffi 20 hours ago

Show HN: a Rust ray tracer that runs on any GPU – even in the browser(github.com)

I’ve been experimenting with Rust lately and wanted a project that would help me explore some of its lower-level and performance-oriented features. Inspired by Sebastian Lague’s videos, I decided to implement my own ray tracer from scratch.

The initial goal was just to render a simple 3D scene in the browser at a reasonable frame rate. It evolved into a small renderer that can: • Run locally or on the web using wgpu and WebAssembly • Perform mesh rendering with a Bounding Volume Hierarchy (BVH) for acceleration • Simulate both direct and indirect illumination for photorealistic results • Be deployed easily as a free web demo using GitHub Pages

The project is far from perfect, but it’s been a fun way to dig deeper into graphics programming and learn more about Rust’s ecosystem. I’m also planning to experiment with Rust for some ML projects next.

GitHub: https://github.com/tchauffi/rust-rasterizer Web demo (desktop browsers): https://tchauffi.github.io/rust-rasterizer/

Would love feedback from anyone who’s built similar projects or has experience with wgpu or ray tracing in Rust.

90 points | 25 comments

eek2121 17 hours ago|

In Firefox, open about:config and set this to true: `dom.webgpu.enabled`.

nomel 11 hours ago|

In Safari < 26:

Settings... -> Advanced -> tick Show features for web developers

Settings... -> Feature Flags -> tick WebGPU*

_bent 15 hours ago||

Why did you call the project rasterizer when it is not using rasterization but raytracing?

SR2Z 14 hours ago|

Rasterization is just the process of converting an image to a raster, which you also have to do in raytracing. It does sound strange though.

skrrtww 16 hours ago||

In Safari 26 on an M1 with WebGPU enabled I get "InvalidStateError: GPUCommandEncoder.beginComputePass: Unable to begin compute pass."

In Chrome I get "Failed to start: Failed to create State. Caused by: failed to find GPU adapter."

So I guess it runs on "some" GPUs, in "some" browsers!

pnm45678 8 hours ago||

And on M5 Safari 26, jacking the samples/pixel setting up high seems to trigger a system reboot, which is most curious

iknowstuff 11 hours ago|||

Works fine on M4. M1 didn't have mesh shaders, maybe that's why?

almostgotcaught 12 hours ago||

works for me just fine on 26; i get

```

live_raytracer-bffaca82311af1dd.js:1484 Uncaught Error: Using exceptions for control flow, don't mind me. This isn't actually an error! at imports.wbg.__wbg_wbindgenthrow_451ec1a8469d7eb6 (

```

but everything else is fine

yunnpp 7 hours ago||

What feedback are you looking for here specifically?

I cannot run the demo on Firefox, but you might get better performance with an 8x4 thread group.

Also, mega-kernels of this sort are generally bad for occupancy. Wavefront path tracing improves this at the expense of additional IO and a more involved implementation. https://research.nvidia.com/publication/2013-07_megakernels-...

Overall your code looks easy to read. Too bad I couldn't run it.

swiftcoder 17 hours ago||

Very cool. Enjoyed playing with the "bounces" slider - it's fascinating how little improvement each additional bounce contributes after about 3 bounces. Severely diminishing returns in terms of the final image quality.

tormeh 17 hours ago||

Demonstrates how important it is to match the scenes with the rendering techniques. You can easily create a corridor with a light at one end that requires lots of bounces for the light to get to the end. But in a game you can just decide to not create that kind of scene. Cyberpunk 2077 basically has no rooms without direct light in them, which makes the game look good even without ray tracing.

Maken 17 hours ago||

That's why virtually every renderer stochastically discards indirect paths with low contribution. Looking at the source code, this one computes every subsequent bounce, even those hitting the perfectly blue sphere after hitting the perfectly green one.

WhitneyLand 18 hours ago||

It looks cool, nice project.

Recommend taking a few minutes to make the web page work on mobile.

For example on iPhone the actual webgpu/ray tracing seems to work fine but html formatting is shoving things over to be barely visible.

tchauffi 18 hours ago|

Thanks! It should work on mobile, you can hide the right panel using the button at the bottom of the screen. That said, performance on mobile is pretty limited because of hardware limitations.

jasonjmcghee 14 hours ago||

performance was 60fps on my phone / worked fine, but as parent said - the sidebar covers 90% of the screen. Worth collapsing by default imo.

gunalx 17 hours ago||

Dosent work in firefox, because of missing webgpu.

tormeh 17 hours ago|

Works on mobile Firefox Nightly

goodpoint 18 hours ago||

It does not run: "unreachable executed"

tchauffi 18 hours ago|

Maybe your browser do not support webgpu. Try using Chrome.

CyberDildonics 16 hours ago||

runs on any GPU – even in the browser

Seems pretty clickbaity and dishonest when that's just what webgl and webgpu means. Just say webgpu.

Also the roughness doesn't apply to the environment map.

cptroot 15 hours ago||

If you click into the code you can see that it depends on `wgpu`, which is a wrapper that uses whichever native API would be appropriate for the platform you're working with. If you run the native compiled version you won't be using WebGPU.

CyberDildonics 13 hours ago||

wgpu is based on webgpu, what is your point here?

The title implies that the reason this exists is because it "runs on any gpu, even in the browser". People have been making raytracers using gpu apis in the browser over and over for the last decade.

That would be like someone claiming their program "multiplies huge matrices using SIMD" and then wrapping eigen. Why make a claim that is just happening because you call the same library as everyone else?

yunnpp 7 hours ago||

I think you're getting lost in the weeds there. I do not see malice in the claim.

The irony is that it does not actually run on my GPU, nor much of other people's, judging by the comments. I don't know where people get this idea that WASM and WebGPU are the holy grail of portability; they are the opposite and the whole ecosystem is a fucking disaster. No offense to OP, though; I can understand the temptation to target that platform.

Anyway, I left more positive feedback in another comment.

knowhistory 18 hours ago|

https://www.jsweet.org/examples/#Ray_tracer

Written in Java then transpiled to JavaScript, been around for years.

nogridbag 16 hours ago|

The OP is real time ray tracing which is running between 30-60FPS on my macbook air while moving the camera and objects around.

Your link appears to be a basic ray tracer which anyone who has taken an intro to computer graphics course in college is likely required to implement and would only need a javascript canvas. To be honest I have no idea how much OPs real-time ray tracing differs in complexity from traditional ray tracing.