Divide and conquer is suboptimal, esp. with so many polygons. You just had luck.
You'd need to sweep over all polygons at once, checking each intersection, and there the angles. This requires some ad hoc preparation. Log(n) instead of exponential. A modified Graham scan or Bentley - Ottoman scan.
You'd need to sweep over all polygons at once, checking each intersection, and there the angles. This requires some ad hoc preparation. Log(n) instead of exponential. A modified Graham scan or Bentley - Ottoman scan.