chore: better support different number of rings

[ggarber]

Better support for variable number of rings removing the hardcoded constant 4 in different places.

[bocytko]

Thanks for the PR. Do you have a branch with a fully working example?
I tried to check out your branch and add a 5th ring and the change breaks due to undefined radius for the new ring.

A few more things will break:

• cartesian_max uses index 3 which is a hardcoded 4-1
• legend_calculation calculates the legend offsets and at least the calculation for dy needs to consider more rings via a formula with ring and 12 rather than the naive switch using mod 2

[rishiraj88]

Nice idea, going forward.