Scene3D

[mhuebert]

This PR introduces a new 3D visualization module in src/genstudio/scene3d.py.

It brings in our first set of interactive scene components using WebGPU, including:

• Components for 3D Visualization: Functions to easily create various 3D primitives:
  • PointCloud: For rendering point clouds with customizable positions, colors, sizes, and transparency.
  • Ellipsoid & EllipsoidAxes: To render solid ellipsoids or their wireframe bounds.
  • Cuboid: For drawing cuboids with position, size, and optional color/alpha settings.
  • LineBeams: For connecting points into beams based on grouping.
• Decorations: The deco function helps create standard decoration dictionaries (indexes, color, alpha, scale) to style scene components uniformly.

Usage notes

• Arrays for columnar data (eg. sizes, alphas, positions and so on) should be flattened, due to javascript not having support for multidimensional arrays. Some effort is made to due this in our python api but it won't handle the common/recommended cases where data is specified within Plot.initialState (we don't know statically how this data is used, so we can't automatically reshape)
• Dense vs Sparse data: if you are specifying an attribute for ALL instances of a component, specify it directly using alpha (same alpha for all) or alphas (an array with one value per instance). Eg. PointCloud(positions=[...], sizes=[...], alpha=...). If you want to specify an attribute for a small number of instances, use a decoration, eg PointCloud(..., decorations=[deco([..indexes..], alpha=...]).

Review/Doc notes

• there are a large number of notebook/scene3d_* example files
• a brief introduction to the system (for the website) is found in docs/learn-more/scene3d.py

[mhuebert]

I've tagged a few people for review, if you have time/interest. This is large PR, and for workflow purposes I'd like to merge it today so that the scene3d docs make it into the website, and we can follow up with further review/changes later.

[sritchie]

Happy to approve and debug later based on a view of the mkdocs files... @chi-collective/gen , @littleredcomputer , if anyone else wants to stare at this please do!