I built a GPU “big bang” particle sim in Rust (wgpu) over a 2-day sprint

I’ve spent a lot of time working on web engines, but had never really touched modern GPU compute directly, so I used this as an excuse to dive in and learn.

What it does:

- ~3 million particles simulated in real time - Interactive framerates (hardware-dependent) - Voxel-based “gravity” field that particles both write to and read from - Fully GPU-driven (compute + rendering)

The basic idea: Particles deposit “mass” into a voxel grid → the grid gets blurred over time → particles sample that field to derive a force → that drives motion.

It’s not physically accurate, but it produces some really interesting emergent structure.

What surprised me: I tapped out at a relatively low particle count.

I’ve pushed GPUs much harder on the web before (tens of millions of grass blades in one of my games), so I expected to go further here. Not sure where the bottleneck is:

- WebGPU vs Metal vs wgpu - Something dumb in my pipeline - Or maybe I’m accidentally hitting a software fallback somewhere

I’m on an M1, so I’d expect this to scale better on something like an RTX 30xx+. The project seems almost entirely GPU-bound, but I wouldn’t be shocked if I’m wrong.

What it’s not:

- No collisions - Not real gravity - No conservation laws - I’m not a physicist, and it shows

This is much more of a visual / emergent system than a real simulation.

Context: I wrote the compute + rendering + simulation logic myself. Used AI to scaffold some surrounding pieces (including this post). This was mostly about learning how to actually use compute, not just read about it.

Thanks: Huge shoutout to the Rust and wgpu teams. The fact that this is even approachable is kind of wild.

If you’re interested, check it out / break it / improve it. PRs welcome — I’ll review and merge anything solid.

Happy to answer questions or get roasted for the physics :)

Comments URL: https://news.ycombinator.com/item?id=47428413

Points: 1

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Fireflies Meadow isn’t ready for prime time yet, but we’re proud of the progress so far and actively iterating on it.

If you’re interested in the engine, the game, or just want to follow along, feel free to reach out on our Discord: https://discord.com/invite/mHsQayQNdp

I’d be curious to hear your feedback on whether the game is working for you or not.

It is hard to describe just how much more can be done on a single thread with just async.

Comments URL: https://news.ycombinator.com/item?id=43435950

Points: 10

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