Transform individual splats

[slimbuck]

This PR add the ability to move/rotate/scale individual splats using transform gizmo and transform panel.

Screen.Recording.2024-10-15.at.11.07.54.mov

The code changes can be summarised as follows:

• the transform panel and gizmos now interact with a Pivot object
• two new TransformHandler classes respond to pivot updates by applying the changes to the scene and updating the undo/redo history
• in order to transform large scenes in realtime we introduce a Transform Palette
  • the palette stores 3x4 transform matrices in an RGBA32F texture
  • each splat has a uint32 transform palette index assigned. 0 means no transform.
  • the transform palette is managed and updated during edits
• since splat positions are dynamic, some JS (cpu) processing has to be moved to GLSL (gpu), including:
  • intersection testing for mask/rect/sphere selections
  • bounding box calculations
  • splat centers updates (used for render sorting of splats)
  • these are all implemented in data-processor.ts

Issues/Concerns

• this change results in higher memory usage (primarily for transform palette indices per splat) and slightly slower rendering due to transform palette
• the transform palette supports 4096 matrices initially and just doubles in size every time more space is needed
• the SPLAT DATA panel doesn't reference the transformed splat positions. this will be fixed in a followup PR.
• Value field manipulation with mouse doesn't work #212 is still present, will be addressed in a followup PR

Testing notes

Full regression testing is needed, specifically:

• PLY and compressed PLY loads correctly
• PLY, compressed PLY and .splat formats save correctly with arbitrary edits
• gizmos work correctly under position/rotation/scale
• the transform panel works correctly under position/rotation/scale changes
• undo/redo history works correctly

[simonbethke]

Saving is currently broken:

TypeError: Cannot read properties of null (reading '0')
    at uw.getMat (splat-convert.ts:74:40)
    at mw (splat-convert.ts:188:40)
    at file-handler.ts:333:28
    at file-handler.ts:330:22
    at async Sy.<anonymous> (file-handler.ts:225:13)

[slimbuck]

Saving is currently broken:

Thanks for this @simonbethke - fixed.

I hadn't tested not changing anything then trying to save yet :)

[simonbethke]

The "Reset Splat" function is not resetting the TransformsPalette

[mvaligursky]

just a note that when you move this to the engine v2 you can use texture.resize()