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jgayfer / bevy_light_2d

General purpose 2D lighting for the Bevy game engine.
MIT License
128 stars 5 forks source link

Does not work in WASM #5

Closed tliron closed 2 months ago

tliron commented 2 months ago

Great library! Unfortunately it doesn't work in WASM, at least not for me. :)

Here's the panic I get (when testing in Firefox). All I did here was add the plugin:

panicked at /home/xxx/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wgpu-0.19.4/src/backend/wgpu_core.rs:3006:5:
wgpu error: Validation Error

Caused by:
    In Device::create_bind_group_layout
      note: label = `lighting_bind_group_layout`
    Too many bindings of type StorageBuffers in Stage ShaderStages(FRAGMENT), limit is 0, count was 1. Check the limit `max_storage_buffers_per_shader_stage` passed to `Adapter::request_device`
jgayfer commented 2 months ago

Thanks for letting me know!

I haven't used wasm before, but I will see what I can piece together 👍

jgayfer commented 2 months ago

@tliron It looks like the library only works with wgpu at the moment. Are you able to get things running by including the webgpu feature flag from Bevy?

I might need to add a note to the README to make this restriction clear.

tliron commented 2 months ago

Hm, well I have avoided WebGPU so far, because it's still broadly unsupported and experimental. I tried a quick build with wgpu, but I'm unable to get it running at all. Firefox doesn't support WebGPU and Chrome gives me a "Unable to find a GPU" panic. I'm on Linux here, so maybe WebGPU isn't support at all.

Do you have an idea of what's stopping bevy_light_2d from supporting plain old WebGL?

jgayfer commented 2 months ago

Yes, I'm fairly certain it's the storage buffer in the shader. I did a quick test removing it (and the point lights), and was able to get it working. I believe if we port that over to a uniform buffer things will work.

See #6 for a tracker.

tliron commented 2 months ago

Additional: I jumped through some hoops to get WebGPU/Chrome/Linux working. It's extremely janky and unbearably slow, but it does work. :) It's just not viable for any of my work at present.

jgayfer commented 2 months ago

Great, thanks for the data point. I'll see about getting WebGL2 working next time I sit down with this.

jgayfer commented 2 months ago

@tliron I took a look at this last night.

Turns out that passing in a runtime sized array into a uniform buffer isn't a supported operation. Sounds like we'd need to get tricky with storing the array of point lights in a texture, and reading the data from there.

There's also the consideration that to support WebGL2, we wouldn't be able to use compute shaders, which I've been hoping to take advantage of for light occlusion.

I'd love to support WebGL2, but I don't currently have a strong understanding on how to reasonably sidestep the limitations.

tliron commented 2 months ago

Yeah, it does sound like it would have to be a different implementation for WebGL. I would add that an OpenGL pipeline could be generally useful for other environments, too, like Android (I think?). But I can understand not wanting to support two different rendering paths.

If you can, though, ... it would be a really nice contribution to the Bevy ecosystem! Bevy + WebGL is used quite a lot for 2D games, for which this plugin adds really amazing pizazz.

jgayfer commented 2 months ago

Definitely. I'd love to support it! It just might require a bit of re-working to get there (or not supporting certain features like light occlusion if we can't find workarounds). Will keep it in mind.

Let's use #6 to track this issue? It's a bit more discover-able.

For now I've added a note to the README to state that web support is currently limited to WebGPU :+1: