bin-pack-with-constraints

Bin Pack With Constraints

A packing algorithm for 2D bin packing. Largely based on code and a blog post by Jake Gordon, and forked from bryanburgers/bin-pack to add maxWidth and maxHeight functionality.

This library packs objects that have a width and a height into as small of a square as possible, using a binary tree bin packing algorithm. After packing, each object is given an (x, y) coordinate of where it would be optimally packed.

The algorithm may not find the optimal bin packing, but it should do pretty will for things like sprite maps.

The default behavior during packing is that the container attempts to maintain a roughly square ratio by making 'smart' choices about whether to grow right or down.

If either a maxWidth or a maxHeight is set, it will try not to grow beyond that limit, and choose instead to grow in the other direction. However, if a block is larger than the given limit, that block's dimension will replace the limit to avoid failure.

Installation

npm install bin-pack-with-constraints

Use

var pack = require('bin-pack');
var bins = [
	{ width: 10,  height: 20 },
	{ width: 100, height: 100 },
	{ width: 50,  height: 19 },
	...
	];

var result = pack(bins);

// result.width: width of the containing box
// result.height: height of the containing box
// result.items: packed items
// result.items[0].x: x coordinate of the packed box
// result.items[0].y: y coordinate of the packed box
// result.items[0].width: width of the packed box
// result.items[0].height: height of the packed box
// result.items[0].item: original object that was passed in

If you want to constrain the width or height of the containing box, you can use the maxWidth or maxHeight option when packing. The maximum doesn't have to be greater than the size of the largest box, but if it isn't you may run into unexpected behavior.

var pack = require('bin-pack');
var bins = [
	{ width: 100, height: 100 },
	{ width: 10,  height: 20 },
	{ width: 50,  height: 19 },
	...
	];

var result = pack(bins, {maxWidth: 105});

// result.width: width of the containing box
// result.height: height of the containing box
// result.items: packed items
// result.items[0].x: x coordinate of the packed box
// result.items[0].y: y coordinate of the packed box
// result.items[0].width: width of the packed box
// result.items[0].height: height of the packed box
// result.items[0].item: original object that was passed in

If your object doesn't have x and y properties, and you don't mind a library writing to your objects, then specify inPlace: true and your objects will have a x and y properties added to them.

var pack = require('bin-pack');
var bins = [
	{ width: 100, height: 100 },
	{ width: 10,  height: 20 },
	{ width: 50,  height: 19 },
	...
	];

var result = pack(bins, { inPlace: true });
// result.width: width of the containing box
// result.height: height of the containing box
// bins[0].x: x coordinate of the packed box
// bins[0].y: y coordinate of the packed box

Contributing

Contributing tests, documentation, or code is all appreciated. All code should be accompanied by valid tests.