KTX2Loader: Return DataTexture for uncompressed formats

[ligaofeng0901]

Description

So far, KTX2Loader doesn't work with WebGPURenderer. If we forcely use it in WebGPURenderer. some errors occur.

WebGPUTextureUtils.js:642 Uncaught TypeError: Cannot read properties of undefined (reading 'width')
    at WebGPUTextureUtils._copyCompressedBufferToTexture (WebGPUTextureUtils.js:642:1)
    at WebGPUTextureUtils.updateTexture (WebGPUTextureUtils.js:370:1)
    at WebGPUBackend.updateTexture (WebGPUBackend.js:1146:1)
    at Textures.updateTexture (Textures.js:243:1)
    at Bindings._init (Bindings.js:99:1)
    at Bindings.getForRender (Bindings.js:33:1)
    at Bindings.updateForRender (Bindings.js:79:1)
    at WebGPURenderer._renderObjectDirect (Renderer.js:1714:1)
    at WebGPURenderer.renderObject (Renderer.js:1658:1)
    at WebGPURenderer._renderObjects (Renderer.js:1597:1)

Solution

Maybe there is another way to load ktx2?

Alternatives

Additional context

No response

[Mugen87]

KTX2Loader does in general work with WebGPURenderer (see https://threejs.org/examples/webgpu_loader_gltf_compressed) but it seems you are trying to load a KTX2 texture that holds uncompressed RGBA data.

The root cause of the runtime error is explained in #29904 (comment).

My preferred solution is that loaders return instances of DataTexture in this case. CompressedTexture should only hold compressed data.

We handled compressed textures differently in WebGLRenderer but this might be a good opportunity to change the behavior. In general, we try to adapt better approaches in WebGPURenderer even if that means it takes longer to support all existing use cases.

[ligaofeng0901]

KTX2Loader does in general work with WebGPURenderer (see https://threejs.org/examples/webgpu_loader_gltf_compressed) but it seems you are trying to load a KTX2 texture that holds uncompressed RGBA data.

The root cause of the runtime error is explained in #29904 (comment).

My preferred solution is that loaders return instances of DataTexture in this case. CompressedTexture should only hold compressed data.

Thanks! I will dive deeper into it and try to find it out.

[donmccurdy]

@Mugen87 I plan to fix the case you're describing, see #29926.

However, are you sure that's what's happening here, and can we reproduce that? I'm not sure what device that supports WebGPU would not also support at least one of the possible compressed target formats for Basis Universal, such that it would fall back to the final option, RGBAFormat.

If the data in the KTX2 was uncompressed to begin with (not Basis Universal) then it should already be creating a DataTexture here:

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

Lines 979 to 994 in de9b967

	if ( UNCOMPRESSED_FORMATS.has( FORMAT_MAP[ vkFormat ] ) ) {
	texture = container.pixelDepth === 0
	? new DataTexture( mipmaps[ 0 ].data, container.pixelWidth, container.pixelHeight )
	: new Data3DTexture( mipmaps[ 0 ].data, container.pixelWidth, container.pixelHeight, container.pixelDepth );
	} else {
	if ( container.pixelDepth > 0 ) throw new Error( 'THREE.KTX2Loader: Unsupported pixelDepth.' );
	texture = new CompressedTexture( mipmaps, container.pixelWidth, container.pixelHeight );
	texture.minFilter = mipmaps.length === 1 ? LinearFilter : LinearMipmapLinearFilter;
	texture.magFilter = LinearFilter;
	}

But maybe I've missed something, I'm not sure how to reproduce this.

[ligaofeng0901]

@Mugen87 @donmccurdy Sorry, the issue I met is cased by there code in my app:

const ktx2Loader = new KTX2Loader();
const renderer = new WebGPURenderer();
ktx2Loader.detectSupport(renderer);

The main reason is we invoke ktx2Loader.detectSupport before the renderer inited. After changing detectSupport to detectSupportAsync, it works. I hope my mistake didn’t mislead you.

We handled compressed textures differently in WebGLRenderer but this might be a good opportunity to change the behavior. In general, we try to adapt better approaches in WebGPURenderer even if that means it takes longer to support all existing use cases.

KTX2Loader is good in my use case. This may be an another issue.

[Mugen87]

Without a correct usage of detectSupport(), things can be indeed misleading since the loader does not work as expected to begin with. If you are not encountering any issues anymore when using the method correctly, that's great.

[ligaofeng0901]

Thing goes good now, close the issue.

[ligaofeng0901]

Also, It may be better If we add a warning here If rendered is not inited.
https://github.com/mrdoob/three.js/blob/dev/examples/jsm/loaders/KTX2Loader.js#L144
This can help users who migrating from WebGL version, like render method in WebGPURenderer.

[Mugen87]

It is not yet possible to check with a public API whether the renderer has been initialized or not. The _initialized property is private.

[ligaofeng0901]

The _initialized property is private.

It really is, I think it should be an open API. One case we met is, we invoke dispose of WebGPURenderer before it is inited, it casues some errors. So I use _initialized to check the state of renderer