Source of the module: r_collide.ml.

The couple (x, y) stands for the position of the rectangle and (w, h) stands for the width and the height.

let r_collide a b =
  if ((a.x + a.w) <= b.x) then (false) else
  if (a.x >= (b.x + b.w)) then (false) else
  if ((a.y + a.h) <= b.y) then (false) else
  if (a.y >= (b.y + b.h)) then (false) else
  (true)

let r_collide_2 a b =
  if ((a.x + a.w) < b.x) then (false) else
  if (a.x > (b.x + b.w)) then (false) else
  if ((a.y + a.h) < b.y) then (false) else
  if (a.y > (b.y + b.h)) then (false) else
  (true)

$ \ocaml r_collide.ml
 false
 true

The first function detects if the rectangles collide-only or if they collide-or-touch.

# collide_only     := false
# collide_or_touch := true