WebGPURenderer: Read-Only and Read-Write Storage Textures Access support in TSL

[RenaudRohlinger]

Related issue: #28455

Description

This PR adds support for Read Only and Read/Write Storage Textures access in TSL.

Example:

const width = 512, height = 512;

const storageTexture = new StorageTexture( width, height );
storageTexture.format = THREE.RedFormat;
storageTexture.type = THREE.FloatType;

const computeTexture = tslFn( ( { storageTexture } ) => {

	const posX = instanceIndex.remainder( width );
	const posY = instanceIndex.div( width );
	const indexUV = uvec2( posX, posY );

	const oldTextureValue = textureLoad( storageTexture, indexUV ).setAccess('read-write')

	const newTextureValue = oldTextureValue.add( 0.1 );

	textureStore( storageTexture, indexUV, newTextureValue, 'read-write' );

} );

This contribution is funded by Utsubo

[sunag]

Could we detect if it's a StorageTexture here instead of moving the setAccess() to TextureNode?

[RenaudRohlinger]

Technically since textureLoad inherits from TextureNode and not StorageTextureNode it's not possible.
We need to be able to specify the access in the reading (textureLoad) via textureLoad( readTex, ivec2( x, y ) ).setAccess( 'read-only' ) that can differ from the writing textureStore( writeTex, uv, value, 'read-write' ).

Alternative would be to add a 4th argument for textureLoad:
textureLoad( readTex, ivec2( x, y ), null, 'read-only' )

[sunag]

I think we would extend generateSnippet to support generateTextureLoad with access on StorageTextureNode and keep TextureNode as it was. This was part of the implementation although not finalized use textureStore just to read texture if you don't add value as parameter to assign, for example: textureStore( storageTexture, indexUV )

[RenaudRohlinger]

Fixed with #29881