Categorical axis

[redhog]

An filterbar for an axis for a categorical column should show as a set of checkboxes or similar.

To filter, encode selected subset as a bitmask using the following strategies:

Category Count	Recommended Approach	Reason
1–32	uint Bitmask	Most efficient; fits in a single register.
33–1024	Uniform Array / UBO	Fast access; remains in high-speed constant memory.
1024+	1D Texture	Scales to large datasets; bypasses uniform hardware limits.