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+# Butterscotch Preprocessor
+
+Butterscotch Preprocessor converts a GameMaker `data.win` file into binary
+texture and audio assets for PlayStation 2 or PlayStation 3 targets.
+
+## Requirements
+
+- Java 21 or newer
+- The included Gradle wrapper
+
+## CLI usage
+
+Run the CLI from the repository root:
+
+```shell
+./gradlew :processor-cli:run --args='/path/to/data.win'
+```
+
+Processed files are written to `output/` by default. To select a target and a
+different output directory:
+
+```shell
+./gradlew :processor-cli:run --args='/path/to/data.win --target ps2 --output ./build/processed'
+```
+
+Paths containing spaces must be quoted inside `--args`:
+
+```shell
+./gradlew :processor-cli:run --args='"/path/to/My Game/data.win" --output "./My Output"'
+```
+
+### Options
+
+```text
+Usage: butterscotch-preprocessor [<options>] <datawinpath>
+
+Arguments:
+  <datawinpath>           Path to the data.win file
+
+Options:
+  -o, --output=<path>     Output directory (default: output)
+  --debug-output=<path>   Dump sprites, backgrounds, fonts, tiles, and atlas
+                          debug images to this directory (PS2 only)
+  --force-4bpp=<regex>    Force matching image names to use at most 16 colors;
+                          the regex must match the whole name and the option
+                          may be repeated (PS2 only)
+  --atlas-size=<pixels>   Width and height of each square texture atlas
+                          (PS2 only)
+  --target=(ps2|ps3)      Output platform (default: ps3)
+  -h, --help              Show CLI help
+```
+
+For example, this PS2 command uses 1024-pixel atlases, forces sprite names
+beginning with `spr_ui_` or `spr_font_` to 4bpp, and writes debug PNGs:
+
+```shell
+./gradlew :processor-cli:run --args='/path/to/data.win --target ps2 --atlas-size 1024 --force-4bpp "spr_ui_.*" --force-4bpp "spr_font_.*" --debug-output ./build/debug'
+```
+
+When processing for PS2, the CLI also discovers related audio beside
+`data.win`:
+
+- `.ogg` and `.wav` files in the same directory
+- `audiogroup<N>.dat` files in the same directory, excluding group 0
+- `.ogg` files recursively inside subdirectories such as `mus/`
+
+## Build a launcher
+
+Create a self-contained application distribution with its runtime
+dependencies:
+
+```shell
+./gradlew :processor-cli:installDist
+```
+
+Run the generated launcher:
+
+```shell
+./processor-cli/build/install/processor-cli/bin/processor-cli \
+  /path/to/data.win --target ps2 --output ./output
+```
+
+Archive distributions can be built with:
+
+```shell
+./gradlew :processor-cli:distZip
+./gradlew :processor-cli:distTar
+```
+
+## Output files
+
+The default PS3 target writes:
+
+- `textures.bin`
+
+The PS2 target writes:
+
+- `CLUT4.BIN`
+- `CLUT8.BIN`
+- `TEXTURES.BIN`
+- `ATLAS.BIN`
+- `SOUNDBNK.BIN`
+- `SOUNDS.BIN`
+
+Supplying `--debug-output` for a PS2 run additionally creates extracted PNGs
+under `sprites/`, `backgrounds/`, `fonts/`, `tiles/`, and `atlas_debug/`.
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