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grovesNL | 1 year ago
I think a better comparison would be more representative of a real game scene, because modern graphics APIs is meant to optimize typical rendering loops and might even add more overhead to trivial test cases like bunnymark.
That said though, they're already comparable which seems great considering how little performance optimization WebGPU has received relative to WebGL (at the browser level). There are also some performance optimizations at the wasm binding level that might be noticeable for trivial benchmarks that haven't made it into Bevy yet, e.g., https://github.com/rustwasm/wasm-bindgen/issues/3468 (this applies much more to WebGPU than WebGL).
> They're 10k triangles and they're not overlapping... There are no textures per se. No passes except the main one, with a 1080p render texture. No microtriangles. And I bet the shader is less than 0.25 ALU.
I don't know your exact test case so I can't say for sure, but if there are writes happening per draw call or something then you might have problems like this. Either way your graphics driver should be receiving roughly the same commands as you would when you use Vulkan or DX12 natively or WebGL, so there might be something else going on if the performance is a lot worse than you'd expect.
There is some extra API call (draw, upload, pipeline switch, etc.) overhead because your browser execute graphics commands in a separate rendering process, so this might have a noticeable performance effect for large draw call counts. Batching would help a lot with that whether you're using WebGL or WebGPU.
FragmentShader|1 year ago
I know, but that's the unique instance where I could find the same project compiled for both WebGL and WebGPU.
> Either way your graphics driver should be receiving roughly the same commands as you would when you use Vulkan or DX12 natively or WebGL, so there might be something else going
Yep, I know. I benchmarked my program with Nsight and calls are indeed native as you'd expect. I forced the Directx12 backend because the Vulkan and OpenGL ones are WAYYYY worse, they struggle even with 1000 triangles.
> That said though, they're already comparable which seems great considering how little performance optimization WebGPU has received relative to WebGL (at the browser level).
I agree. But the whole internet is marketing WebGPU as the faster thing right now, not in the future once it's optimized. The same happened with Vulkan but in reality it's a shitshow on mobile. :(
> There is some extra API call (draw, upload, pipeline switch, etc.) overhead because your browser execute graphics commands in a separate rendering process, so this might have a noticeable performance effect for large draw call counts. Batching would help a lot with that whether you're using WebGL or WebGPU.
Aha. That's kinda my point, though. It's "Slow" because it has more overhead, therefore, by default, I get less performance with more usage than I would with WebGL. Except this overhead seems to be in the native webgpu as well, not only in browsers. That's why I consider it way slower than, say, ANGLE, or a full game engine.
So, the problem after all is that by using WebGPU, I'm forced to optimize it to a point where I get less quality, more complexity and more GPU usage than if I were to use something else, due to the overhead itself. And chances are that the overhead is caused by the API itself being slow for some reason. In the future, that may change. But at the moment I ain't using it.
grovesNL|1 year ago
It really depends on how you're using it. If you're writing rendering code as if it's OpenGL (e.g., writes between draw calls) then the WebGPU performance might be comparable to WebGL or even slightly worse. If you render in a way to take advantage of how modern graphics APIs are structured (or OpenGL AZDO-style if you're more familiar), then it should perform better than WebGL for typical use cases.