collide-2d-aabb-tilemap

Determines whether a moving axis-aligned bounding box collides with a tilemap, and prevents intersection.

Based off collide-2d-tilemap. The key difference is that this module provides a non-destructive API, and doesn't depend on aabb-2d.

Example

Here's a playable demo.

Example usage:

var collideAabbTilemap = require('collide-2d-aabb-tilemap')

var tilemap = [
    [ 0, 0, 0, 1 ],
    [ 1, 0, 0, 1 ],
    [ 1, 0, 0, 1 ],
    [ 1, 1, 1, 1 ]
]

// (0,0) - (16,16)
var player = [0, 0, 16, 16]

// collideAabbTilemap(field, size of tile in pixels, [width, height])
collide = collideAabbTilemap(my_tilemap, 32, [4, 4])

my_game_event_loop(function(dt) {
  var vec = get_player_input() * dt 

  collide(player, vec, function(moveAxis, moveDir, tileIdx, tileCoords) {
    // true => solid
    return tileIdx > 0
  })
})

The algorithm used is taken from this article. Detection and correction is applied on each X and Y axis separately.

Usage

var collide = collideAabbTilemap(array, tilesize[, dimensions])

Produces a collide(aabb, vec2, oncollide) function.

array may be a single-dimension array (or ndarray) of integers OR a function of the form fn(tileX, tileY) -> integer.

tilesize are the pixel dimensions of a tile.

dimensions is a size 2 array of integers, [width, height]. If it is not provided, the map will be assumed to be square.

var offset = collide(aabb, moveDelta, onCollide)

Attempt to advance aabb by moveDelta against the aforementioned tilemap. Non-destructive.

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 [x, y].

onCollide is a callback function, taking the following arguments:

• moveAxis: an integer representing the axis of movement. 0 (X) or 1 (Y).
• moveDir: either -1 or 1, denoting the direction of the movement.
• tileIdx: the tile integer data of the tile a candidate collision has been detected against.
• tileCoords: a size 2 array of tile coordinates.

If the callback returns a truthy value, the tile will be treated as solid, and no further tiles will be checked along this axis.

License

MIT