WebGPURenderer: Add support for non-instanced meshes to StorageBuffer

[RenaudRohlinger]

It's currently not possible to use the storage buffers as attribute informations on the vertices for a classic mesh. This PR fix the issue.

Alternative could be to introduce breaking changes and replace everything with StorageInstancedBufferAttribute for the current compute particle demos and use StorageBufferAttribute for classic meshes.

In the WebGL Backend I guess using attributes[ 0 ].isInstancedBufferAttribute should be enough? Not sure of a case where we would use instanced and basic array buffer at the same time in a compute shading.

This contribution is funded by Utsubo

[sunag]

The alternative StorageInstancedBufferAttribute sounds good to me, seems like one less hack to worry about.

@mrdoob @Mugen87 Do you have any thoughts on this?

[RenaudRohlinger]

Let's give it a try!

[mrdoob]

Hmm... What's a storage buffer in the context of WebGL?

[RenaudRohlinger]

Hmm... What's a storage buffer in the context of WebGL?

A storage buffer in the context of WebGL is essentially a buffer that is typically utilized to imitate compute shading via a transform feedback program. Specifically, it operates as a dual-buffer system that switches every frame in a ping-pong manner. This setup is used to replicate the functionality of a WebGPU storage_buffer, which provides read_write access.

Basically I wouldn't really look too far as to what its meaning is in the WebGL context since its application here is only to replicate what is normally not doable and just mimic WebGPU behaviors.