WebGPURenderer: support using 3d textures in shaders with texture3d() and add VolumeNodeMaterial() and examples.

[aardgoose]

As title,

WebGPU and WebGL2 backends supported.
Note WGSL doesn't support a matrix inverse function so the inversion of the object's matrixWorld is carried out in JS.

Two examples based on WebGL2 examples: volume - cloud (simplified) and volume - perlin, both using the VolumeNodeMaterial().

(also Chrome release 125 now supports rendering to 3d textures. https://chromestatus.com/feature/5196871364771840 )

[RenaudRohlinger]

Overall, what do you think about letting the users handle the map property themselves into the custom testNode?

For example something like this:

The VolumeNodeMaterial does not require a map by default to work, and it is used only within the custom testNode override function. This change would also allow for more complex custom testNode functions, UV mapping, and so on. /cc @sunag

[aardgoose]

@sunag I had to add a hack in ReferenceNode after #28407 (before that PRm this hack wasn't needed) not sure what the correct solution is.

Overall, what do you think about letting the users handle the map property themselves into the custom testNode?

For example something like this:

The VolumeNodeMaterial does not require a map by default to work, and it is used only within the custom testNode override function. This change would also allow for more complex custom testNode functions, UV mapping, and so on. /cc @sunag

It works for me, initially I was just getting the functionality of the existing examples. Things like the base color should probably use materialColor etc to match existing materials.

[mrdoob]

I guess this PR should be updated now that #28433 got merged?

[aardgoose]

I guess this PR should be updated now that #28433 got merged?

done.