   SAT Axis Problems
  I'm trying to implement the Separating Axis Theorem to test for collision between 2D rectangles but I'm encountering a problem.  The collision detection works fine until I rotate or flip my rectangle.  When I do that I get the wrong results sometimes when colliding from top/bottom.My rectangles are set up as 4 points (upperLeft, UpperRight, LowerRight, lowerLeft) and when I rotate them I don't bother to change these points so for example if I rotate the rectangle 90* the UpperLeft point will actually be in the UpperRight position on the screen.  Is this the problem and I need to change these points? Or am I calculating my axes wrong?   
  We're not psychic. Show some code.   ;  If you are doing SAT and your rectangles are not square then yes, you need to rotate your points even if by 90 degrees. In this case the axes remain the same but your projections onto the axes will be wrong.   ;  Like Zahlman, I think the description of the problem is too vague for anyone to propose a solution, please elaborate, and if posible, post the code where you have isolated the issue.   