atlaspack

Pack rectangles (or images) into a rectangle (or canvas texture atlas). View the demo.

example

This will load 0-99 images and fit them onto a canvas texture atlas:

// create a canvas
var canvas = document.createElement('canvas');
document.body.appendChild(canvas);
canvas.width = 128;
canvas.height = 128;

// Create a starting atlas based on the canvas
var atlas = require('atlaspack')(canvas);

for (var i = 0; i < 100; i++) {
  var img = new Image();
  img.id = i;
  img.src = 'images/' + i + '.png';
  img.onload = function() {
    atlas.pack(img);
  };
}

You can pack generic rectangles into an atlas as well. The following example will create a 512x512 atlas and load random shapes into document.body every second:

// Specify a width and height of the starting atlas
var atlas = require('atlaspack')(512, 512);

(function loop() {
  var width  = Math.random() * 32;
  var height = Math.random() * 32;

  var node = atlas.pack({width: width, height: height});

  var div = document.createElement('div');
  div.style.position = 'absolute';
  div.style.width  = width + 'px';
  div.style.height = height + 'px';
  div.style.left   = node.rect.x + 'px';
  div.style.top    = node.rect.y + 'px';
  document.body.appendChild(div);

  setTimeout(loop, 1000);
}());

api

atlaspack([...])

Takes either 1 canvas argument, 2 width, height arguments or 4 x, y, width, height arguments. Returns an instance of Atlas.

atlaspack.Atlas([...])

Takes either 1 canvas argument, 2 width, height arguments or 4 x, y, width, height arguments.

atlas.pack(rect || image || object)

Recursively tries to pack rect (or image, object) into the atlas. Will return false if fails to fit the rect otherwise will return the atlas node the rect has been packed into:

var Atlas = require('atlaspack').Atlas;
var Rect = require('atlaspack').Rect;

var atlas = new Atlas(128, 128), node;

node = atlas.pack(new Rect(0, 0, 32, 32));
node = atlas.pack({x: 0, y: 0, w: 32, h: 32});

var img = new Image();
img.src = 'myimage.png';
img.onload = function() {
  node = atlas.pack(img);
};

atlas.expand(rect || img || object)

Will recursively expand the atlas to fit a new rect then pack the rect into the expanded atlas. Returns the newly expanded atlas:

var atlas = require('atlaspack')(128, 128);
var dontfit = {x: 0, y: 0, w: 256, h: 256};
var node = atlas.pack(dontfit);
if (node === false) {
  atlas = atlas.expand(dontfit);
}

atlas.index()

Returns a flat array of rects which have images within the atlas. Useful for retrieving an atlas key:

var atlas = require('atlaspack')(128, 128);

function done() {
  atlas.index().forEach(function(rect) {
    console.log('Name: ' + rect.name);
    console.log('Coords: ' + rect.x + ', ' + rect.y);
  });
}

for (var i = 0; i < 100; i++) {
  var img = new Image();
  img.src = 'images/' + i + '.png';

  // Will use the id || name || src of the image as the rect.name
  img.id = i;

  img.onload = function() {
    atlas.pack(img);
    if (i === 99) done();
  };
}

atlas.uv([width, height])

Returns an object with rect names as keys containing an array of UV mapping coordinates between 0-1 with TRBL:

var uvmap = atlas.uv();
/* {
              TOP   RIGHT  BOTTOM  LEFT
  'name':  [ [0,0], [1,0], [1,1], [0,1] ],
} */

Specify a width and height to override the dimensions the UVs will calculate from. Otherwise it will use the atlas.rect width and height.

atlas.json([input])

Exports or imports a JSON key for the ability to save the atlas state and restore it:

var jsonkey = atlas.json();
// then later
atlas = atlas.json(jsonkey);

// make sure to set your canvas if using a canvas too
atlas.canvas = mycanvas;

atlas.tilepad

Set this boolean property to true if you would like each packed image to pad itself with a tiled pattern of itself. Useful for avoiding texture bleeding when mipmapping.

atlaspack.Rect(x, y, w, h)

Creates a rectangle instance.

rect.fitsIn(rect)

Returns a boolean whether a rect fits within another rect.

rect.sameSizeAs(rect)

Returns a boolean whether a rect is the same size as another rect.

install

With npm do:

npm install atlaspack

using standalone / non-browserify

It is wrapped in an UMD for use outside of browserify.

Add a script tag to your HTML and use globally exposed atlaspack variable:

<script src="node_modules/atlaspack/index.js"></script>
<script>
var atlas = window.atlaspack(canvas);
</script>

release history

• 0.2.7 - Wrap in UMD for use outside of commonjs loaders.
• 0.2.6 - Fix _uvcache should be an object (@deathcap).
• 0.2.5 - clearRect before placing image onto a canvas.
• 0.2.4 - Add width/height overrides to uv method.
• 0.2.3 - Add tilepad property to help with mipmapping.
• 0.2.2 - Ability to get and set JSON key.
• 0.2.1 - Add uv method for uv coordinates.
• 0.2.0 - Add expand and index methods.
• 0.1.0 - initial release

license

Copyright (c) 2014 Kyle Robinson Young
Licensed under the MIT license.