WebGPURenderer: Fix rendering morphed meshes.

[Mugen87]

Fixed #31903.

Description

When two meshes with shared geometry and material share the same node builder state, rendering ends up wrong because the second meshes uses the (referenced) morph target influence values from the first mesh.

Unless this is somehow fixed on the node side by not coupling the uniform buffers directly to a specific mesh, RenderObject must make sure to return different cache keys for such meshes.

There was also a bug in NodeMaterialObserver that did not update the cached morph target influence values to detect changes which is fixed with this PR as well.

[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	584.32 161.46	584.41 161.49	+94 B +28 B
WebGPU Nodes	582.93 161.22	583.02 161.25	+94 B +28 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	653.67 176.96	653.77 176.99	+94 B +32 B
WebGPU Nodes	607.78 166.14	607.88 166.16	+94 B +27 B

[Mugen87]

@sunag I'm not sure but below code does not seem to work as expected:

three.js/src/nodes/accessors/MorphNode.js

Line 239 in d9eec4f

influence.assign( reference( 'morphTargetInfluences', 'float' ).element( i ).toVar() );

If this should make sure to use the morphTargetInfluences data from the current mesh, something else is broken. The UBO is not correctly updated and always uses the data from the "first" mesh.

[sunag]

If this should make sure to use the morphTargetInfluences data from the current mesh, something else is broken. The UBO is not correctly updated and always uses the data from the "first" mesh.

The verification is failing in NodeMaterialObserver.containsNode() because the system is not yet unified when it comes to binding updates, code refactoring should follow this path soon #26673 (comment) This should not happen if the user uses a non-built-in node (custom) in material.

As soon as I finish this inspection I will pay attention to this, the tool should be useful for this refractoring.