Fast rectangle to rectangle intersection?

Question

What's a fast way to test if 2 rectangles are intersecting?

Answer 1

A rectangle can be represented by two coordinates, its top left coordinate and its bottom right coordinate. Those will tell you all you need to know about where the rectangle is located.

Example: Top left coordinate is (0,0), bottom right is (1,-1). This rectangle has 4 points at (0,0), (1,0), (0,-1), (1,-1).

So what's a quick way to determine if two rectangles do NOT intersect? Well, if either rectangle's bottom edge is above the other's top edge OR either rectangle's right edge is to the left of the other's left edge. Any other situation means they do intersect.

Good luck!