should say "draw an CIRCLE_COL where a y-axis to current y-axis is 1:1, x-axis to current is 1:2 and shape size to current size is 2:1". Or there should be another way to tell that to renderer. What do you think? Are there any chances for implementation?
The primitive shapes are always unit circles, squares, and triangles. You change there size by scaling the coordinate space that they are drawn in. There is no way to do what you want right now. The rule parameter feature that I have mentioned before would do this pretty easily.