parsepico

Pico-8 Cartridge Parser

This project provides a command-line Go program that parses a Pico-8 cartridge (.p8 file), extracts graphics (sprites) and map data, and saves them as PNG images. It also handles "dual-purpose" sections (--3 and --4) commonly used as shared area between sprites and map data.

Features

• Extract Spritesheet
  Reads the __gfx__ section of a Pico-8 cart and creates:

  • A map.png image that renders the map data (from the __map__ section).
  • A spritesheet.png image that stacks sub-sections vertically (created from section_0.png, section_1.png, etc.).
  • Individual sprite files in sprites/sprite_000.png up to sprites/sprite_XXX.png (either 128 or 256 sprites).

• Dual-Purpose Sections
  If you pass the flags --3 or --4, the parser will also handle the higher sprite regions (sprite 128..191 and 192..255, respectively) which can store extra map or game data.

• Configurable

  • Choose a custom .p8 file path using --cart.
  • Remove old artifacts (the sprites folder, map.png, spritesheet.png) before generating new output with --clean.

TODO

Soon enough ...

• Add support for parsing the code into AST.
• Add support for parsing the audio.

Requirements

• Go 1.18+ (or any recent Go version)
• A Pico-8 .p8 cartridge file

Usage

1. Build the binary:

   go build -o parsepico8
   

   This produces an executable named parsepico8.

2. Run the parser:

   ./parsepico8 [flags]
   

   Common flags:

   • --cart <file.p8>: Specify the path to your Pico-8 cartridge.
     Default: /Users/pgeorgia/Library/Application Support/pico-8/carts/test.p8
   • --3: Parse dual-purpose section 3 (sprites 128..191).
   • --4: Parse dual-purpose section 4 (sprites 192..255).
   • --clean: Remove the sprites directory, map.png, and spritesheet.png if they exist.

Examples

• Parse a normal .p8 file (no extra sections):

  ./parsepico8 --cart mygame.p8
  

  Generates:

  • map.png
  • spritesheet.png (with 4 sections stacked, each 128×32)
  • sprites/ folder with 256 sprites and section_0.png .. section_3.png

• Use dual-purpose section 3:

  ./parsepico8 --cart mygame.p8 --3
  

  Generates:

  • map.png including extra data from sprites 128..191
  • spritesheet.png with only 2 sections total
  • sprites/ folder with 128 sprites and section_0.png, section_1.png

• Use dual-purpose section 4:

  ./parsepico8 --cart mygame.p8 --4
  

  Similar behavior to --3 but for sprites 192..255.

• Use both --3 and --4:

  ./parsepico8 --cart mygame.p8 --3 --4
  

  Includes sprites 128..255 as dual-purpose data, exports only the first 128 sprite files and 2 section images.

• Clean old outputs first:

  ./parsepico8 --cart mygame.p8 --3 --clean
  

  Removes old sprites/, map.png, and spritesheet.png before extracting again.

Output Files

• map.png
  A rendered view of the tilemap section (__map__) plus any dual-purpose rows (if --3 or --4 are used).

• spritesheet.png
  A vertical concatenation of each sub-image (section_0.png, section_1.png, up to section_3.png).

  • If no flags are used, you'll have 4 sections, each 128×32 → final size 128×128.
  • If --3 or --4 are used, only 2 sections are made (128×64 total).

• sprites/sprite_NNN.png
  Individually exported 8×8 sprites, up to sprite_255.png if no dual-purpose flags are used, or up to sprite_127.png if --3 or --4 is specified.

• sprites/section_X.png
  Each sub-image of the full 16×16 sprite sheet (128×32 segments). These are stacked into the final spritesheet.png.

• spritesheet.json A JSON file containing detailed information about each available sprite (based on --3/--4 flags). Includes sprite ID, position on the sheet, pixel data (array of color indices), flags (bitfield and individual booleans), a used flag (true if not completely black), and the expected filename (sprite_XXX.png). It also contains metadata: sprite dimensions (8x8), grid dimensions (16x16), available sprite ranges, section usage flags (--3/--4), and the full PICO-8 palette.

  Example (spritesheet.json snippet):

  {
    "version": "1.0",
    "description": "PICO-8 spritesheet export",
    "sprites": [
      {
        "id": 0,
        "x": 0,
        "y": 0,
        "width": 8,
        "height": 8,
        "pixels": [
          [ 0, 0, 0, 0, 0, 0, 0, 0 ],
          [ 0, 0, 0, 0, 0, 0, 0, 0 ],
          [ 0, 0, 7, 0, 0, 7, 0, 0 ],
          [ 0, 0, 0, 7, 7, 0, 0, 0 ],
          [ 0, 0, 0, 7, 7, 0, 0, 0 ],
          [ 0, 0, 7, 0, 0, 7, 0, 0 ],
          [ 0, 0, 0, 0, 0, 0, 0, 0 ],
          [ 0, 0, 0, 0, 0, 0, 0, 0 ]
        ],
        "flags": {
          "bitfield": 0,
          "individual": [ false, false, false, false, false, false, false, false ]
        },
        "used": true,
        "filename": "sprite_000.png"
      },
      // ... more sprites
    ],
    "metadata": {
      // ... metadata fields (palette, available ranges etc.)
    }
  }
  

• map.json A JSON file describing the map layout. Includes the map dimensions (width, height - depends on --3/--4), a name ("main"), and a list of map cells. Each cell has an x, y coordinate and the sprite ID placed at that location. The coordinates and sprite IDs cover the base map section and potentially the shared memory sections if --3/--4 are used.

  Example (map.json snippet):

  {
    "version": "1.0",
    "description": "PICO-8 map export",
    "width": 128,
    "height": 32, // or 48/64 depending on --3/--4 flags
    "name": "main",
    "cells": [
      {
        "x": 0,
        "y": 0,
        "sprite": 0
      },
      {
        "x": 1,
        "y": 0,
        "sprite": 0
      },
      // ... many more cells
    ]
  }
  

Expected Output

./parsepico8 --cart $PICO8/carts/celeste.p8 --3 --4 --clean

Tilemap:

Spritesheet:

Individual sprites:

License

This code is provided under the MIT License. Feel free to use, modify, and distribute as needed.

Enjoy parsing your Pico-8 carts!