AABB Collision Detection.md

title	notetype	date
AABB Collision Detection	feed	25-02-2022

Axis-Aligned Bounding Box is one of the simplest collision detection methods in 2d [[Game Development]], 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!")
  }
}

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Status: #🌲