crunch

This is a command line tool that will pack a bunch of images into a single, larger image. It was designed for Celeste, but could be very helpful for other games.

It is designed using libraries with permissible licenses, so you are able to use it freely in your commercial and non-commercial projects. Please see each source file for its respective copyright and license.

Features

Export XML, JSON, or binary data
Trim excess transparency
Rotate images to fit
Control atlas size and padding
Premultiply pixel values
Recursively scans folders
Remove duplicate images
Caching to prevent redundant builds
Multi-image atlas when the sprites don't fit
Support for indexed pngs'
Support for using palette file for indexed format (act, JASC, MS pal, GIMP, Paint.net and png)
Support for Aseprite format

What does it do?

Given a folder with several images, like so:

images/
    player.png
    tree.png
    enemy.png
    mario.ase

It will output something like this:

bin/
    images.png
    images.xml
    images.hash

Where images.png is the packed image, images.xml is an xml file describing where each sub-image is located, and images.hash is used for file caching (if none of the input files have changed since the last pack, the program will terminate).

There is also an option to use a binary format instead of xml.

Usage

crunch [options] <inputFilename1,inputFilename2,inputFilename3...> <outputFilename> [paletteFilename]

For example...

crunch -a -t -v -u -r assets/characters,assets/tiles bin/atlases/atlas

This will output the following files:

bin/atlases/atlas.png
bin/atlases/atlas.json
bin/atlases/atlas.hash

Options

option	alias	description
`-o <xml\|bin\|json>`	`--output <xml\|bin\|json>`	saves the atlas data in xml, binary or json format
`-f <n>`	`--format <n>`	texture format
`-a`	`--alpha`	premultiplies the pixels of the bitmaps by their alpha channel
`-t`	`--trim`	trims excess transparency off the bitmaps
`-v`	`--verbose`	print to the debug console as the packer works
`-i`	`--ignore`	ignore caching, forcing the packer to repack
`-u`	`--unique`	remove duplicate bitmaps from the atlas
`-r`	`--rotate`	enabled rotating bitmaps 90 degrees clockwise when packing
`-s <n>`	`--size <n>`	max atlas size (`<n>` can be `4096`, `2048`, `1024`, `512`, `256`, `128`, or `64`)
`-w <n>`	`--width <n>`	max atlas width (overrides `--size`) (`<n>` can be `4096`, `2048`, `1024`, `512`, `256`, `128`, or `64`)
`-h <n>`	`--height <n>`	max atlas height (overrides `--size`) (`<n>` can be `4096`, `2048`, `1024`, `512`, `256`, `128`, or `64`)
`-p <n>`	`--padding <n>`	padding between images (`<n>` can be from `0` to `16`)
`-b <n\|p\|7\|f>`	`--binstr <n\|p\|7\|f>`	string type in binary format (`n`: null-terminated, `p`: prefixed (int16), `7`: 7-bit prefixed, `f`' fixed 16 bytes)
`-l`	`--last`	use file's last write time instead of its contents for hashing
`-d`	`--dirs`	split output textures by subdirectories
`-n`	`--nozero`	if there's only one packed texture, then zero at the end of its name will be omitted (ex. `images0.png` -> `images.png`)

Palette Format

For indexed png's the supported palette formats supported are act, jasc, mspal, gimp, paint.net and png.

Binary Format

crch (0x68637263 in hex or 1751347811 in decimal (little endian))
[int16] version (current version is 0)
[byte] --trim enabled
[byte] --rotate enabled
[byte] string type (0: null-termainated, 1: prefixed (int16), 2: 7-bit prefixed, 3: fixed 16 bytes)
[int16] num_textures (below block is repeated this many times)
    [string] name
    [int16] tex_width
    [int16] tex_height
    [int16] tex_format
    [int16] num_images (below block is repeated this many times)
        [int16] img_frame_index
        [string] img_name
        [string] img_label
        [byte] img_loop_direction
        [int16] img_duration
        [int16] img_x
        [int16] img_y
        [int16] img_width
        [int16] img_height
        [int16] img_frame_x         (if --trim enabled)
        [int16] img_frame_y         (if --trim enabled)
        [int16] img_frame_width     (if --trim enabled)
        [int16] img_frame_height    (if --trim enabled)
        [byte] img_rotated          (if --rotate enabled)
        [byte] img_palette_slot

Splitting

If --dirs (or -d) is enabled output textures will be split by subdirectories.

For example:

crunch -b -d bin/images images with input images

images/
    chars/
        player.png
        enemy.png
    other/
        tree.png
        box.png

will output

bin/
    images_chars.png (with player.png and enemy.png)
    images_chars.hash
    images_chars.bin
    images_other.png (with tree.png and box.png)
    images_other.hash
    images_other.bin
    images.bin

If player.png is the only changed image then only images_chars.bin will be packed and images_other.bin will be reused in images.bin.

This can be used for faster packing: unchanged subdirectories will be skipped instead of packing unchanged images.

But there're some limitations:

multiple inputs and images as inputs are not supported
images in input directory itself will be ignored and not packed

Building on Linux

cd linux/
make

Credits

Ben Baker - Support for indexed pngs', palette files and Aseprite support
Chevy Ray Johnston - Original crunch
Nebulaxin - Updated crunch
Randy Gaul - cute_aseprite

benbaker76 / crunch