Max Rects Packer

A simple max rectangle 2d bin packing algorithm for packing glyphs or images into multiple sprite-sheet/atlas. Minimalist with no module dependency.

This is a evolved version of Multi-Bin-Packer with much efficient packing algorithm. All interfaces and methods are inherited so no tweaks needed in your current code except module name.

It differs from the long list of similar packages by its packing approach: Instead of creating one output bin with a minimum size this package is trying to create a minimum number of bins under a certain size. This avoids problems with single massive image files that are not browser-friendly. This can be especially useful for WebGL games where the GPU will benefit from spritesheets close to power-of-2 sizes.

And you can also save/load to reuse packer to add new sprites. (Below is a demo atlas packed with two difference bitmap fonts)

Installing

npm install @vanchelo/maxrects-packer --save

Usage

let MaxRectsPacker = require('maxrects-packer').MaxRectsPacker;
const options = {
  smart: true,
  pot: true,
  square: false,
  allowRotation: true,
  tag: false,
  border: 5,
}; // Set packing options
let packer = new MaxRectsPacker(1024, 1024, 2, options); // width, height, padding, options

let input = [ // any object with width & height is OK since v2.1.0
  { width: 600, height: 20, name: 'tree', foo: 'bar' },
  { width: 600, height: 20, name: 'flower' },
  { width: 2000, height: 2000, name: 'oversized background', frameWidth: 500, frameHeight: 500 },
  { width: 1000, height: 1000, name: 'background', color: 0x000000ff },
  { width: 1000, height: 1000, name: 'overlay', allowRotation: true },
];

packer.addArray(input); // Start packing with input array
packer.next(); // Start a new packer bin
packer.addArray(input.slice(2)); // Adding to the new bin
packer.bins.forEach(bin => {
  console.log(bin.rects);
});

// Reuse packer
let bins = packer.save();
packer.load(bins);
packer.addArray(input);

Test

npm test

API

Note: maxrects-packer requires node >= 4.0.0

new MaxRectsPacker(maxWidth, maxHeight[, padding, options])

Creates a new Packer. maxWidth and maxHeight are passed on to all bins. If padding is supplied all rects will be kept at least padding pixels apart.

• options.smart packing with smallest possible size. (default is true)
• options.pot bin size round up to smallest power of 2. (default is true)
• options.square bin size shall alway be square. (default is false)
• options.allowRotation allow 90-degree rotation while packing. (default is false)
• options.tag allow tag based group packing. (default is false)
• options.border atlas edge spacing (default is 0)

packer.add(width, height, data) +1 overload

Adds a rect to an existing bin or creates a new one to accommodate it. data can be anything, it will be stored along with the position data of each rect.

packer.add({width: number, height: number, ... }) +1 overload

Adds a rect to an existing bin or creates a new one to accommodate it. Accept any object with width & height. If you are using typescript, that means any class extends MaxRectsPacker.IRectangle

packer.addArray([{width: number, height: number, ...}, ...])

Adds multiple rects. Since the input is automatically sorted before adding this approach usually leads to fewer bins created than separate calls to .add()

packer.repack(quick: boolean = true)

Repack all elements inside bins. If quick == true, only bins with dirty flag will be repacked. If false is passed, all rects inside this packer will be re-sort and repacked, might result different bin number. Slower but high packing efficiency.

packer.next()

Stop adding new element to the current bin and return a new bin. After calling next() all elements will no longer added to previous bins.

let bins = packer.save()

Save current bins settings and free area to an Array of objects for later use. Better to JSON.stringify(bins) and store in file.

packer.load(bins)

Restore previous saved let bins = JSON.parse(fs.readFileSync(savedFile, 'utf8')); settings and overwrite current one. Continue packing and previous packed area will not be overlapped.

packer.bins

Array of bins. Every bin has a width and height parameter as well as an array rects.

packer.bins[n].rects

Array of rects for a specific bin. Every rect has x, y, width, height, rot and data. In case of an rect exceeding maxWidth/maxHeight there will also be an oversized flag set to true.

Support for 90-degree rotation packing

If options.allowRotation is set to true, packer will attempt to do an extra test in findNode() on rotated Rectangle. If the rotated one gives the best score, the given Rectangle will be rotated in the Rectangle.rot set to true.

Support for tag based group packing

If options.tag is set to true, packer will check if the input object has tag: string property, all input with same tag will be packed in the same bin.

Support for oversized rectangles

Normally all bins are of equal size or smaller than maxWidth/maxHeight. If a rect is added that individually does not fit into those constraints a special bin will be created. This bin will only contain a single rect with a special "oversized" flag. This can be handled further on in the chain by displaying an error/warning or by simply ignoring it.

Packing algorithm

Use Max Rectangle Algorithm for packing, same as famous Texture Packer