GUI guide

Start a project

Run zig build run from the repository, or launch the built Packrat executable. Choose File > New Project or File > Open Project. Add one or more input folders from the toolbar or by dropping folders onto the app.

Save the project as a .packrat file. Project-relative folders are easiest to move between machines. Open projects appear as tabs; the active project is the one being packed and exported.

Configure packing

The right-hand column controls the atlas:

• Max size and Algorithm control the atlas page canvas and placement.
• Trim mode chooses how transparent edges are handled. Trim keeps the original frame size in metadata; Crop (Keep Position) removes transparent pixels while preserving the original offset; Crop removes them and resets the offset.
• Padding, Margin, and Border control spacing inside and around an atlas page. Extrude duplicates edge pixels to reduce filtered seams.
• More contains power-of-two sizing, alpha threshold, and the optional root-folder name prefix.

Choose an export

Select a Data Format in the export column, choose the output base path with the ... button, then press EXPORT. Keep the generated descriptor and atlas page image together. The selected format determines the descriptor's file extension.

The preview shows the packed rectangle, original frame size, trim offset, atlas page, and animation frame index. Use it to verify that your runtime uses the original frame size and trim offset when drawing trimmed frames.

Save and inspect

Use Ctrl+S to save the current .packrat project. Changes are marked with * in the project tab until saved. F6 opens the profiler; project loads, repacks, exports, and UI drawing have separate timing trees.