collide-2d-tilemap
2d tilemap collisions made simple-ish
npm install collide-2d-tilemap
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Version | 0.0.1 last updated a year ago |
License | MIT |
Keywords | collision, 2d, games, aabb, tilemap |
Repository | https://github.com/chrisdickinson/collide-2d-tilemap (git) |
Dependencies | None |
collide-2d-tilemap
an api for user-defined collision-detection between aabb-2d objects and tilemaps.
var my_tilemap = [
0, 0, 0, 1
, 1, 0, 0, 1
, 1, 0, 0, 1
, 1, 1, 1, 1
]
var collisions = require('collide-2d-tilemap')
, collide
var player = aabb([0, 0], [16, 16])
, vec = [0, 0]
// collisions(field, size of tile in pixels, [width, height])
collide = collisions(my_tilemap, 32)
my_game_event_loop(function(dt) {
vec = get_player_input() * dt
collide(player, vec, function(axis, tile_data, coords, dir, diff) {
if(tile) {
vec[axis] = diff
return true
}
})
})
the method used is borrowed from higherorderfun.
in short:
- for movement in each axis (x, y):
- we go from the tile coordinate of the leading edge of the movement to the tile coordinate of the destination of that edge.
- we go from the base tile coordinate of the opposite axis to the max tile coordinate of the opposite axis.
- for each of those tile coordinates
<x>
and<y>
, we call theoncollision
callback. if it returns true, we've hit something and we stop checking that axis for collisions. - we apply the movement contained in
vec[axis]
to the box.
this lets you do things like add slopes, add effects that don't necessarily stop collision, etc, etc.
Warning
For best results, use integers. If you're using gl-matrix, you can simply swap out
vec2.create
withvec2.create = function() { return new Int32Array(2) }
.
API
collision(field, tilesize[, dimensions]) -> collide function
Produces a collide(aabb, vec2, oncollide)
function.
field
may be a single-dimension array of integers (in which case dimensions
can be inferred if not provided), or it may be a function in the form fn(tile_x_idx, tile_y_idx) -> tile data integer
. if it's a function, dimensions
is required.
tilesize
is the pixel size of a tile.
dimensions
is an array of integers [width, height]
.
if it is not provided it will attempt to set to [Math.sqrt(field.length), Math.sqrt(field.length)]
(that is, it assumes a square tilemap).
collide(aabb, vec, oncollide) -> undefined
attempt to advance aabb
by vec
against the tilemap. destructive, it will actually call aabb.translate
.
vec
is assumed to be a gl-matrix
-style vec2
, or [x, y]
.
aabb
is assumed to be a aabb-2d instance.
oncollide
is a callback function, taking:
axis
: an integer representing the axis of movement.0
or1
.tile
: the tile data represented at this candidate coordinate.coords
: a two dimensional array of tile coordinates.dir
:1
or-1
, representing the direction of movement along this axis.dX
: the distance to the appropriate edge of this tile, if a collision is desired (such that you can writevec[axis] = dX
if you'd like to collide with that tile).
If your callback returns true
, it is assumed that you're done checking tiles along this access and it will move to the next axis if any.
License
MIT