I would like to implement the distinct 0..7 plot modes:
0..3 use relative coordinates.
4..7 use absolute coordinates
0,4 move, do not draw anything.
1,5 draw in foreground colour.
2,6 draw in inverse colour (this is FabGL's NOT operation I think).
3,7 draw in background colour
FabGL appears to have inverse colour support only for dots and lines, but it would be good to implement all these modes for them. Relative coordinates, fg and bg drawing can also be implemented for the other graphics primitives.