AABB Collision Detection

Axis-Aligned Bounding Box is one of the simplest collision detection methods in 2d Game DevelopmentGame Development
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Status: #🗺️

, which only works on 2d rectangles that aren't rotated (their sides are parallel/perpendicular).

AABB works by checking if sides of rectangle A are outside of the opposite sides of rectangle B. For example, if top side of rectangle A is below bottom side of rectangle B, we know the two rectangles aren't colliding no matter what.

Given rectangles A and B with sides top, bottom, left and right, the formula we can use to check for collision would look something like this:

Collision is detected if all of these statements are true (just draw two rectangles and follow along):

  • A.left is to the left of B.right
  • A.right is to the right of B.left
  • A.top is above B.bottom
  • A.bottom is below A.top

We could represent the same idea in code like this:

package main

type rectangle struct {
  x int
  y int
  width int
  height int

func main() {
  a := rectangle{x: 5, y: 5, width: 5, height: 5}
  b := rectangle{x: 3, y: 3, width: 5, height: 5}

  if (a.x < b.x + b.width) && 
     (a.x + a.width > b.x) && 
     (a.y < b.y + b.height) && 
     (a.y + a.height > b.y) {
	fmt.Println("Collision detected!")

Status: #🌲