Feature Proposal: `PointerNode`

[RenaudRohlinger]

Description

Can we consider adding a PointerNode, similar to ScreenNode, to make a pointer node accessible in both compute and render shaders?

This could simplify and optimize pointer-based interactions and we could potentially offer built-in raycasting support as an option.

The webgpu_compute_geometry.html example would be a great use case to test and demonstrate this feature.

Potential API:

pointer = // normalized
pointerViewport = // pixels


// potential API
pointer(sceneToRaycast)

pointer.xy // coordinates
pointer.z // depth of intersection
pointer.w.greaterThan(0) // raycast is hitting

/cc @sunag @Mugen87

[sunag]

I think in this sense it is worth investing in a GPU-based Raycaster. In pointer(). Maybe we could have names as a shortcut, for example pointer.pressed instead of pointer.w.greaterThan(0).