Single-pass IBL shadow voxelization for WebGPU

[MiiBond]

This changes the voxelization strategy for WebGPU to allow it to be done in a single pass (though, generation of mips still takes additional steps). This is possible using textureStore to write to arbitrary texels in a 3D texture. It also uses vertex pulling to correctly determine the provoking vertex for each triangle and retrieve adjacent vertices so that we can calculate the triangle's normal. This is used to swizzle the xyz components to maximize the rasterized area and not miss voxels.

Anywho, this makes updating shadows for animated meshes much more plausible. I'm not sure the best way to do this but currently, in my playground, I'm doing this:

const frameSkip = 1;
let frame = 0;
scene.onAfterAnimationsObservable.add(() => {
    if (enableIblShadows) {
        if (frame == 0 && scene.animatables.find((anim) => !anim.paused)) {
            iblShadowsPipeline.updateVoxelization();
            iblShadowsPipeline.resetAccumulation();
        }
        if (frame === frameSkip) {
            frame = 0;
        } else {
            frame++;
        }
    }
});

Is there a better way to query whether there is currently an animation happening?

[bjsplat]

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To prevent this PR from going to the changelog marked it with the "skip changelog" label.

[bjsplat]

Snapshot stored with reference name:
refs/pull/17270/merge

Test environment:
https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/17270/merge/index.html

To test a playground add it to the URL, for example:

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/17270/merge/index.html#WGZLGJ#4600

Links to test babylon tools with this snapshot:

https://playground.babylonjs.com/?snapshot=refs/pull/17270/merge
https://sandbox.babylonjs.com/?snapshot=refs/pull/17270/merge
https://gui.babylonjs.com/?snapshot=refs/pull/17270/merge
https://nme.babylonjs.com/?snapshot=refs/pull/17270/merge

To test the snapshot in the playground with a playground ID add it after the snapshot query string:

https://playground.babylonjs.com/?snapshot=refs/pull/17270/merge#BCU1XR#0

[bjsplat]

Interaction tests

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/17270/merge/testResults/interactionplaywright/index.html

[bjsplat]

WebGL2 visualization test reporter:

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/17270/merge/testResults/webgl2playwright/index.html

[bjsplat]

Devhost visualization test reporter:

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/17270/merge/testResults/devhostplaywright/index.html

[bjsplat]

Visualization tests for WebGPU

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/17270/merge/testResults/webgpuplaywright/index.html

[Popov72]

This changes the voxelization strategy for WebGPU to allow it to be done in a single pass (though, generation of mips still takes additional steps). This is possible using textureStore to write to arbitrary texels in a 3D texture. It also uses vertex pulling to correctly determine the provoking vertex for each triangle and retrieve adjacent vertices so that we can calculate the triangle's normal. This is used to swizzle the xyz components to maximize the rasterized area and not miss voxels.

Anywho, this makes updating shadows for animated meshes much more plausible. I'm not sure the best way to do this but currently, in my playground, I'm doing this:

const frameSkip = 1;
let frame = 0;
scene.onAfterAnimationsObservable.add(() => {
    if (enableIblShadows) {
        if (frame == 0 && scene.animatables.find((anim) => !anim.paused)) {
            iblShadowsPipeline.updateVoxelization();
            iblShadowsPipeline.resetAccumulation();
        }
        if (frame === frameSkip) {
            frame = 0;
        } else {
            frame++;
        }
    }
});

Is there a better way to query whether there is currently an animation happening?

In a real-world scenario, I think we would let the user decide when to update the voxelization (meshes can also be moved without using animation, a custom vertex shader can apply deformation, etc.). But for a test PG, I think this is fine.

Let us know when the PR is ready for review!