Here's something I thought would be useful for you guys. This works by dividing the triangle into 3 little triangles (one vertex attached to the mouse coords) and adding the sum of those triangles. If the sum is equal to the big triangle's area, the mouse is in triangleland. Credit to @-Rex- for the PTE - I was going to use it for something else too but that fell in on itself. Credit to @TheLogFather for the fast tri filler
