[WIP] Add CubeTexture blur

[elalish]

The idea here is to make the PMREM cubemap blur function available as a generic public blur method for a CubeTexture. So far I only have a sketch, but this being my first attempt at using TSL, I've run into some early problems that I'd like to ask @sunag about.

[github-actions[bot]]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	339.44 79.06	339.44 79.06	+0 B +0 B
WebGPU	488.86 135.68	489.66 135.89	+798 B +212 B
WebGPU Nodes	488.33 135.55	489.1 135.77	+775 B +220 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	465.3 112.11	465.3 112.11	+0 B +0 B
WebGPU	558.8 151.3	559.79 151.53	+996 B +232 B
WebGPU Nodes	514.87 141.07	515.87 141.29	+996 B +224 B

[sunag]

I'd like to ask @sunag about.

I can help with whatever you need :)

[elalish]

Thanks @sunag - that got me unstuck for a bit. However, in my last commit I'm trying to pull in some of the #29900 changes but I hit a weird error, this.value is null in the function below:

getTransformedUV( uvNode ) {

		if ( this._matrixUniform === null ) this._matrixUniform = uniform( this.value.matrix );

I would guess this has something to do with my outputDirection node, but I don't think I've changed anything about it? In any case, fodder for a clearer error message. Any thoughts?

[sunag]

that got me unstuck for a bit. However, in my last commit I'm trying to pull in some of the https://github.com/mrdoob/three.js/pull/29900 changes but I hit a weird error, this.value is null in the function below:

I pushed a commit to fix set uniform value, this happened because texture( null ) is uniform, you can change the value by changing the .value property. But I think we can improve this error message.

[elalish]

Ah, thank you again! I don't know how you manage to develop all this without TS. I have the actual blur function written now - I just need to test it.

[elalish]

Okay, I might have this close to working, and I updated the new API with feedback from @mrdoob. However, upon trying to test it, I realized that CubeRenderTarget is not exported to the public API - it inherits from WebGLCubeRenderTarget which is, but that doesn't have any of the new TSL stuff. Where should this function be exposed?

[elalish]

Since this is my last day at Google (and as a maintainer of MV, see https://github.com/google/model-viewer/discussions/4975) I don't think I'll get a chance to finish this PR. Hopefully it looks useful enough for someone else to pick up and push over the finish line. Thanks for all the help, @sunag! The TSL you've built is quite impressive, though hopefully by the time I play with it again it'll have a few more docs 😄.

[sunag]

@elalish This news took me by surprise. You have done an incredible job over the years with MV and with all the improvements in physical-based materials, tone mapping, etc. I have always found your high level work and rich in detail, your work will certainly be missed by the community. I hope we can meet again on life's journey and I wish you all the best in your achievements.

[elalish]

Thanks a lot @sunag! If you ever find yourself in New Zealand, come visit.