collide-2d-aabb-aabb

Determines whether a moving axis-aligned bounding box (AABB) collides with other AABBs.

collide-2d-aabb-aabb provides methods for testing against either a single AABB or a set of them in 2D space.

Installation

$ npm install collide-2d-aabb-aabb

Example: Test vs Single AABB

var collideSingle = require('collide-2d-aabb-aabb').single

var player = [0, 0, 16, 16]
var motion = [5, 5]
var crate = [18, 1, 32, 32]

var offset = collideSingle(player, motion, crate)
console.log(offset)

outputs

[2, 5]

Example: Test vs Set of AABBs

var collideSet = require('collide-2d-aabb-aabb').set

var player = [0, 0, 16, 16]
var motion = [5, 5]
var crates = [
  [18, 1, 32, 32]
  [7, 19, 32, 32]
]

function getCrate (cb) {
  cb(crates[0])
  cb(crates[1])
  cb(null)
}

var offset = collideSet(player, motion, getCrate, onCollide)
console.log(offset)

function onCollide (box, axis, dir) {
  console.log(box, axis, dir)
}

outputs

[18, 1, 32, 32], 0, 1
[7, 19, 32, 32], 1, 1
[2, 3]

Detection and correction is applied on each X and Y axis separately, resulting in 0-2 calls to onCollide.

Usage

var single = require('collide-2d-aabb-aabb').single
var set = require('collide-2d-aabb-aabb').set

var offset = single(aabb, moveDelta, aabb2)

Attempt to advance aabb by moveDelta against the impeding aabb2. Non-destructive.

If there is no collision, offset == moveDelta. Otherwise, it will be shorter in one or both axes.

aabb and aabb2 are assumed to be a size 4 array of the form [x, y, width, height].

moveDelta is assumed to be a gl-matrix-style vec2 or array [x, y].

var offset = set(aabb, moveDelta, getAabb, onCollide)

Attempt to advance aabb by moveDelta against the set of impeding AABBs provided by the getAabb function. Non-destructive.

getAabb is assumed to be a function with a single parameter, cb, which is called to give size 4 arrays (of the form [x, y, width, height]) to check collisions against. You must call cb(null) to indicate getAabb is finished providing values.

If there is no collision, offset == moveDelta. Otherwise, it will be shorter in one or both axes.

aabb is assumed to be a size 4 array of the form [x, y, width, height].

moveDelta is assumed to be a gl-matrix-style vec2 or array [x, y].

onCollide is a callback function, taking the following arguments:

• aabb: the size 4 array that the collision took place against. Will be === to the array provided by getAabb.
• moveAxis: an integer representing the axis of movement. 0 (X) or 1 (Y).
• moveDir: either -1 or 1, denoting the direction of the movement.

License

MIT