December 5, 2005 at 10:45 am · Edit

I came across a problem just like the overlapping rectangles, but with only one dimention — time. “Do date ranges overlap?” We came up with:

Overlap = A.start before B.end && B.start before A.end

Likewise, you can remove the negative logic with the following:

1. the right edge of A is to the *RIGHT* of the left edge of B
2. the left edge of A is to the *LEFT* of the right edge of B
3. the bottom of A is *BELOW* the top of B
4. the top of A is *ABOVE* the bottom of B

IF (1 && 2 && 3 && 4) THEN collision == TRUE;

Both solutions are fail-fast, so the change is mostly semantic.