Luckily, arc length isn’t too gnarly for those (same Wikipedia page), but you still have one equation with two variables.
I would have to think hard about whether those give you a unique solution.
I also doubt that spiral would give you uniform coverage of the cone (and that probably, is the real requirement, not constant angles), but again, I would have to do some thinking.
oh, interesting variation for uniform coverage! that is indeed what i'd want for the tree. in building a road around a cone, a constant angle would be more desirable.
Luckily, arc length isn’t too gnarly for those (same Wikipedia page), but you still have one equation with two variables.
I would have to think hard about whether those give you a unique solution.
I also doubt that spiral would give you uniform coverage of the cone (and that probably, is the real requirement, not constant angles), but again, I would have to do some thinking.