WGSLNodeBuilder: Improve isCustomStruct() checking

[Spiri0]

#30394 #30487

I recreated the PR because I had big problems with creating the screenshot and the branch was completely destroyed as a result. I was only able to create the screenshot with changes in puppeteer.js and the screenshot still doesn't fit.
The code itself works perfectly. @sunag you have a new node in mind for the structArray anyway. That's why I'm holding off on experimenting with screenshots for the moment

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	336.33 78.33	336.33 78.33	+0 B +0 B
WebGPU	547.22 151.68	547.37 151.73	+146 B +49 B
WebGPU Nodes	546.57 151.52	546.72 151.57	+146 B +49 B

🌳 Bundle size after tree-shaking

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

	Before	After	Diff
WebGL	465.78 112.28	465.78 112.28	+0 B +0 B
WebGPU	621.61 168.13	621.75 168.18	+146 B +52 B
WebGPU Nodes	576.48 157.44	576.63 157.49	+146 B +51 B

[Spiri0]

@sunag Is there a way to update parts of a storageBufferAttribute from the CPU side?
The advantage of the CPU is that it can pre-calculate geometries with 64bit precision
That's my naive thought, but that doesn't work.

positionBuffer.array.set( instancePositions, instanceSlot * instancePositions.length );
positionBuffer.needsUpdate = true;

I also had an example with interleaved buffers in mind but that would be a bit more extensive.

[Spiri0]

@sunag I've removed the example because I can't get the screenshot to work. I have no idea why it keeps going black. It works perfectly when I run the example itself. I also get a black screen with other examples.
This PR works perfectly, as I've been including it in my threejs version for the past three releases to keep my apps running.

I'll probably need this also for my voxelizer in the future. I created it to simulate real buoyancy. With the voxelizer I can calculate the volume of misshapen bodies very well.

https://github.com/Spiri0/Threejs-WebGPU-Voxelizer

I also switched the IFFT ocean to buffers. It works much better that way.

[sunag]

@Spiri0 I'll check this PR this weekend. Thanks!

[Spiri0]

@sunag The extension in src/nodes/core/StructNode.js doesn't even have anything to do with the structArray. The extension in src/renderers/webgpu/nodes/WGSLNodeBuilder.js is sufficient for structArrays. I just find it useful to read the number of members of a struct elsewhere. I use it. This way I avoid unnecessary hard coding.

[sunag]

@Spiri0 Can you confirm if with this change works for you?

[Spiri0]

@Spiri0 Can you confirm if with this change works for you?

Yes, that looks good, it's working. I see you solved it elsewhere in the code, interesting.

[sunag]

Yes, it should be useful for other functions like builder.getPropertyName(). Thanks for testing and sorry for the delay.