Get the points of intersection from 2 rectangles

Question

Let say that we have two rectangles, defined with their bottom-left and top-right corners. For example: rect1 (x1, y1)(x2, y2) and rect2 (x3, y3)(x

Answer 1

You can deal with the x and y direction separately.

Assume that x1 <= x3 (the first box is at least as far to the left as the second). Then, there is overlap if and only if x1 <= x3 <= x2.

Similarly, assume y1 <= y3 (the first box is at least as far to the bottom as the second). Then, there is overlap if and only if y1 <= y3 <= y2.

If there is overlap in both directions, there is a rectangle overlapping. You can find the coordinates by sorting the x and y coordinates and selecting the middle two.

In pseudocode:

if (((x1 <= x3 && x3 <= x2) || (x3 <= x1 && x1 <= x4)) // x-overlap
    &&
    ((y1 <= y3 && y3 <= y2) || (y3 <= y1 && y1 <= y4)) // y-overlap
) {
    int[] xs = {x1, x2, x3, x4};
    int[] ys = {y1, y2, y3, y4};
    sort(xs);
    sort(ys);

    // bottom-left: xs[1], ys[1]
    // top-right:   xs[2], ys[2]
}