Determine if two rectangles overlap each other?

Question

I am trying to write a C++ program that takes the following inputs from the user to construct rectangles (between 2 and 5): height, width, x-pos, y-pos. All of these rectang

Answer 1

It is easier to check if a rectangle is completly outside the other, so if it is either

on the left...

(r1.x + r1.width < r2.x)

or on the right...

(r1.x > r2.x + r2.width)

or on top...

(r1.y + r1.height < r2.y)

or on the bottom...

(r1.y > r2.y + r2.height)

of the second rectangle, it cannot possibly collide with it. So to have a function that returns a Boolean saying weather the rectangles collide, we simply combine the conditions by logical ORs and negate the result:

function checkOverlap(r1, r2) : Boolean
{ 
    return !(r1.x + r1.width < r2.x || r1.y + r1.height < r2.y || r1.x > r2.x + r2.width || r1.y > r2.y + r2.height);
}

To already receive a positive result when touching only, we can change the "<" and ">" by "<=" and ">=".