WebGPURenderer: Missing compressed texture formats

[hybridherbst]

Description

I tried switching KTX2Loader to WebGPU because I saw some errors in one of our apps, and it turns out there are quite a few errors that can be reproduced from webgl_loader_texture_ktx2.

Additionally, I'm not sure how to get the behaviour of renderer.setScissor() in WebGPURenderer; I commented it out here because it throws exceptions.

Reproduction steps

1. Have local three.js for development
2. Open webgl_loader_texture_ktx2.html
3. Change the importmap to "three": "../build/three.webgpu.js",
4. Change WebGLRenderer to WebGPURenderer
5. Add if ( renderer.isWebGPURenderer ) await renderer.init(); below renderer creation
6. Comment out renderer.setScissor(...) (not sure how to work around this)
7. Open the page and scroll down
8. The first few files work fine
9. Scroll further. Then, you get warnings:

10. Scroll further. Then, you get errors:

11. Scroll to the end. Now, you get unrecoverable errors (Note: these files load fine with KTX2Loader: Add VK_FORMAT_ASTC_6x6_SFLOAT_BLOCK_EXT #31689).

Code

Follow the steps above;
or copy from https://github.com/needle-tools/three.js/blob/feature/ktx2loader_webgpu/examples/webgl_loader_texture_ktx2.html

Live example

https://raw.githack.com/needle-tools/three.js/feature/ktx2loader_webgpu/examples/webgl_loader_texture_ktx2.html

Screenshots

No response

Version

r180dev

Device

Desktop

Browser

Chrome

OS

MacOS

[donmccurdy]

Other than a known limitation for ASTC HDR ...

three.js/examples/jsm/loaders/KTX2Loader.js

Line 192 in ca3194a

astcHDRSupported: false, // https://github.com/gpuweb/gpuweb/issues/3856

... I believe the rest of the issues are missing or broken features in WebGPURenderer, as the same THREE.Texture instances should be valid in any renderer. Agreed that it would be nice to get an equivalent of webgl_loader_texture_ktx2 working in WebGPURenderer!

[hybridherbst]

@Mugen87 Do you think this could be classified as bug? The same things work fine in WebGLRenderer. I found these errors by attempting to switch an app over to WebGPU, and running into this problem.

[Mugen87]

Agreed, it's more a bug than an enhancement since the texture compression formats are supposed to work.

Two missing formats are RGB_S3TC_DXT1_Format and RGBA_BPTC_Format. Do you mind naming the texture formats from the spec which should be used to implement these compression types?

https://www.w3.org/TR/webgpu/#texture-formats

AFAICS, these can't be used with WebGPU.

[Mugen87]

31698 fixes the usage of rgb9e5ufloat with the WebGPU backend and also the wrong colors of rg11b10ufloat.

[hybridherbst]

Thank you! I have (yet) no idea about WebGPU specifics, so sadly I can't name the right formats.

@Mugen87 regarding the renderer.setScissor(...) issue (which doesn't seem to work at all in WebGPURenderer in this example), do you want me to open a separate issue or is this known already?

[Mugen87]

I have (yet) no idea about WebGPU specifics, so sadly I can't name the right formats.

@donmccurdy Can we let KTX2Loader produce different formats for WebGPURenderer? Unless you discover the formats in the spec, we need alternatives like bc1-rgba-unorm or bc7-rgba-unorm.

[Mugen87]

regarding the renderer.setScissor(...) issue (which doesn't seem to work at all in WebGPURenderer in this example), do you want me to open a separate issue or is this known already?

The viewport and scissor computation follows a different convention. I'll migrate the KTX2 example WebGPURenderer with fixed code.

[donmccurdy]

Can we let KTX2Loader produce different formats for WebGPURenderer? Unless you discover the formats in the spec, we need alternatives like bc1-rgba-unorm or bc7-rgba-unorm.

Not sure I understand you sorry, do you mean forcing a Basis Universal texture to be transcoded to bc1-unorm, even if a 'better' format is supported, so that we can test bc1-unorm? Maybe, but I'm not sure what conversions the basis transcoder allows... I've been finding it a bit simpler to create standalone compressed (not Universal) .ktx2 examples in webgl_loader_texture_ktx2, and could certainly add more that way.

[Mugen87]

What I mean is that KTX2Loader produces textures with RGB_S3TC_DXT1_Format and RGBA_BPTC_Format which are not supported by WebGPU. So the loader must return different formats.