spacetelescope/sphere — pull request #45 by mdboom (2014-09-09 18:12:05+00:00)
Title: Correct area calculation

This finally resolves the problems with calculating the area of concave polygons, such that we no longer have to project to 2D -- the area is now calculated directly using the standard Girard's theorem (with some cleverness about vertex ordering to get around the problems with concave polygons). This should resolve #44 and make the areas much more accurate in general.

Also adds a fast C implementation to calculate areas, which is now the hot spot when calculating area.

@cdeil, @perrygreenfield, @bernie-simon