WebGPURenderer: Allow manual mipmap creation with StorageTexture

[RenaudRohlinger]

Description

Allow handling manually mipmap of StorageTexture and writing to specific mipLevel via compute:

const storageTexture = new THREE.StorageTexture( width, height );
storageTexture.generateMipmaps = true;
storageTexture.mipmapsAutoUpdate = false;
...
const createComputeTexture = ( mipLevel ) => Fn( ( { storageTexture, mipLevelIndex, mipWidth } ) => {
textureStore( storageTexture, indexUV, outputColor ).setMipLevel( mipLevel ).toWriteOnly();
})

This contribution is funded by Utsubo

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	338.24 79.14	338.24 79.14	+0 B +0 B
WebGPU	589.9 162.96	590.25 163.06	+348 B +100 B
WebGPU Nodes	588.51 162.72	588.86 162.81	+348 B +99 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	469.7 113.74	469.7 113.74	+0 B +0 B
WebGPU	659.22 178.36	659.42 178.42	+199 B +57 B
WebGPU Nodes	613.23 167.54	613.43 167.6	+199 B +58 B

[Makio64]

@RenaudRohlinger instead of manualMipmaps maybe computedMipmaps is more explicit ?

[RenaudRohlinger]

I think computed feels too specific, I like manualMipmaps for the concept of handling manually the mipmaps. But I get your point!

[sunag]

I think we could use mipmapsAutoUpdate, that would be more in line with matrixAutoUpdate. Normally, automatic processes are the properties assigned as true as default.

[RenaudRohlinger]

Updated the PR accordingly to your feedbacks @sunag! Now using mipmapsAutoUpdate = false.