# FastPack
[](https://crates.io/crates/fastpack)
[](https://github.com/Hexeption/FastPack/actions/workflows/ci.yml)
[](https://www.rust-lang.org)
Texture atlas packer written in Rust. Ships as a Tauri desktop app and a headless CLI. Designed as an open-source replacement for TexturePacker.
<img width="800" height="1396" alt="Screenshot 2026-03-07 at 12 47 08 pm" src="https://github.com/user-attachments/assets/fe9df165-6800-465f-801d-b1655536edbf" />
## Features
**Packing**
- MaxRects (5 heuristics), Grid, and Basic strip algorithms
- Trim modes: None, Trim, Crop, CropKeepPos, Polygon (convex hull)
- Extrusion, rotation, nine-patch metadata, pivot points
- Alias detection — deduplicates pixel-identical sprites
- Multipack — overflow sprites across multiple sheets
- Multi-resolution scale variants with per-variant suffix
**Export**
- Data formats: JSON Hash, JSON Array, Phaser 3, PixiJS
- Texture formats: PNG (oxipng lossless), JPEG (mozjpeg), WebP, DXT1 (BC1), DXT5 (BC3)
- Pixel formats: RGBA8888, RGB888, RGB565, RGBA4444, RGBA5551, Alpha8
**Desktop app**
- Real-time atlas preview
- Collapsible sprite tree with thumbnail previews
- Watch mode — repacks on file change
- `.fpsheet` project files (TOML)
- Nine-patch and pivot editors per sprite
- Drag-and-drop folders and project files
- Multi-language UI
## Install
Download the desktop app for your platform from the [releases page](https://github.com/Hexeption/FastPack/releases):
- **Windows** — `fastpack-windows-x86_64-setup.exe`
- **macOS (Apple Silicon)** — `fastpack-macos-aarch64.dmg`
- **macOS (Intel)** — `fastpack-macos-x86_64.dmg`
- **Linux** — `fastpack-linux-x86_64.AppImage`
Or install the CLI from crates.io:
```sh
cargo install fastpack
```
## CLI Usage
```sh
# Pack a directory of sprites
fastpack pack sprites/ --output output/
# Pack with options
fastpack pack sprites/ --output output/ \
--max-width 2048 --max-height 2048 \
--trim-mode trim \
--data-format phaser3 \
--allow-rotation \
--multipack
# Load settings from a project file
fastpack pack --project atlas.fpsheet
# Watch for changes and repack automatically
fastpack watch sprites/ --output output/
# Split an atlas back into individual sprites
fastpack split atlas.png atlas.json --output-dir sprites/
# Generate a default project file
fastpack init --output atlas.fpsheet
```
Run `fastpack <subcommand> --help` for the full flag list.
## Project File
Settings live in a `.fpsheet` TOML file:
```toml
[meta]
version = "1"
[output]
name = "atlas"
directory = "output/"
texture_format = "png"
pixel_format = "rgba8888"
data_format = "json_hash"
quality = 95
[layout]
max_width = 4096
max_height = 4096
size_constraint = "pot"
force_square = false
allow_rotation = true
pack_mode = "good"
border_padding = 2
shape_padding = 2
[sprites]
trim_mode = "trim"
trim_threshold = 1
extrude = 0
detect_aliases = true
[algorithm]
type = "max_rects"
heuristic = "best_short_side_fit"
[[variants]]
scale = 1.0
suffix = "@1x"
mode = "smooth"
[[sources]]
path = "sprites/"
filter = "**/*.png"
```
## Export Formats
`data_format` in the project file or `--data-format` on the CLI accepts:
- `json_hash` — TexturePacker-compatible JSON with frames as an object keyed by sprite ID. Default.
- `json_array` — Same structure but frames as an array, each entry with a `filename` field.
- `phaser3` — Single JSON file with a `textures` array. Compatible with `scene.load.multiatlas()`.
- `pixijs` — JSON Hash format compatible with PixiJS sprite sheet loaders.
## Building from Source
Requires Rust 1.85+.
**CLI only:**
```sh
git clone https://github.com/Hexeption/FastPack
cd FastPack
cargo build --release -p fastpack
```
The binary is at `target/release/fastpack`.
**Desktop app:**
The Tauri app also requires Node.js and pnpm. From the `crates/fastpack-tauri` directory:
```sh
pnpm install
pnpm tauri build
```
The installer is placed under `src-tauri/target/release/bundle/`.
## License
Licensed under [MIT](LICENSE).