atlaspack

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();
  };
}

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

release history

• 0.2.0 - Add expand and index methods.
• 0.1.0 - initial release

license

Copyright (c) 2013 Kyle Robinson Young
Licensed under the MIT license.