craftyjs/Crafty — pull request #465 by starwed (2013-05-15 16:03:33+00:00)
Title: Fix SAT test

The SAT collision test in core was expecting the wrong overlap. It uses `Crafty.circle` to generate two octagonal polygons; their minimal overlap is actually `-15 cos[pi/8] ~= -13.86`. The previous incorrect overlap wasn't completely arbitrary: it was `-20 cos[pi/8]`.

For reference, two perfect circles would have an overlap of -15. But this is testing that SAT works, not how well we approximate circles!