plotting aesthetics for vertex vs primitive vs object

[mdsumner]

We need to differentiate

• continuous: the vertex "v" table
• discrete: the primitives or the object "o" table

Examples are the colour of a country in countriesHigh (discrete) vs. the colour scale across triangles (continuous).

Are there lessons from ggplot2 or scales for this?

Could we have "fill_cts" and "fill_dsc" args, mutually exclusive?

[mdsumner]

had an attempt at this in broken-dev-loop-object branch but it needs more preparation - somehow to always flip between structural and relational without having to think

[mdsumner]

A key aspect is that in rgl ):

• shade3d expects material properties per vertex, and the it/ib index expands those out internally
• rgl. or plot/triangles/lines3d expects those properties per vertex, since they are explicitly expanded anyway for that usage

(I think this is right but needs to be demonstrated clearly. )

Rgl just doesn't have a concept of object, just like polygon and polypath and lines do not.

So a default behaviour may be to look for material properties on the object table, then on the index table/s, then finally on the vertices. I think this gives some easy ways to provide user-controlled nuance.