Sprite tools

The repository is a collection of sprite tools for the MSX2.

Files

• README.md: this file
• png2sprites.py: conversion script that reads PNG files in RGB and converts them into MSX2 compatible VRAM sprite data.
• spritecheck.py: verifies if sprite sheet is MSX2 VRAM-compatible.
• samples/wit.pal: 16-colour palette triples (8-bit RGB values) that specify an MSX2 palette. The zeroth colour is used to eliminate PNG background colour.
• samples/wit.png: sample image of Wit from Treasure of Uşas.
• samples/WIT.BAS: simple BASIC code that displays Wit sprite in SCREEN 5.
• samples/snake.pal: 15 color triples (RGB) that specifies a MSX2 palette.
• samples/snake.png: sample image of Snake from Metal Gear 1.
• samples/SNAKE.BAS: simple BASIC code that displays Snake sprite in SCREEN 5.
• samples/palette.pal: 16-colour palette triples (8-bit RGB values) used in palette.png.
• samples/palette.png: sample image using all colours.
• samples/PALETTE.BAS: simple BASIC code the displays the sprite generated from palette.png.

png2sprites.py

Converts png image into MSX2 sprites. Resulting sprites will always align perfectly over previous layer. Sample images are from the wiki https://www.msx.org/wiki/The_OR_Color. png2sprites.py is a heavily modified version of png2sprites.py script tool from reidrac's https://gitlab.com/reidrac/ubox-msx-lib set of tools and libraries.

How to use it

In addition to the source PNG image, you may provide a palette file, which is basically a tuple of 16 RGB triplets. The first colour in the tuple is MSX colour index 0 (transparent), which png2sprites.py uses to remove the background from the original PNG file.

(255,0,255),(0,0,0),(145,109,0),(109,72,0),(36,36,36),(72,72,72),(109,109,109),(255,255,255),(109,109,109),(0,72,218),(255,0,0),(218,182,145),(182,109,0),(0,145,72),(0,72,36),(0,0,0)

If you don't provide a palette file, png2sprites.py will scan the image and generate its own palette.

Help message

usage: png2sprites.py [-h] [--version] [-i ID] [-b] [-a] [-c] [-p PAL_FILE] [-m MIN] image

PNG to MSX2 sprites

positional arguments:
  image                 image to convert

options:
  -h, --help            show this help message and exit
  --version             show program's version number and exit
  -i ID, --id ID        variable name (default: sprites)
  -b, --basic           BASIC output (default: C header)
  -a, --asm             ASM output (default: C header)
  -c, --colors          include palette colors in C or ASM output
  -p PAL_FILE, --palette PAL_FILE
                        set of colors to use from file
  -m, --minimise        try to minimise palette by brute force

The --minimise option will attempt to minimise the number of sprites by OR-colour replacement after palette permutation and may take several seconds if not minutes. It is an experimental feature and may increase your carbon footprint and return stupid results.

You can refresh sample results with:

./png2sprites.py -i wit -b -p samples/wit.pal samples/wit.png > samples/WIT.BAS
./png2sprites.py -i snake -b -p samples/snake.pal samples/snake.png > samples/SNAKE.BAS

spritecheck.py

Checks if a sprite sheet respects OR-colour combination. You can specify maximum sprites per slot. Default value 2 allows up to 3 colours per line (one colour for each sprite and the extra OR-colour, c3 = c1 | c2), while value 3 allows up to 7 colours per line: c1, c2, c3, c1 | c2, c1 | c3, c2 | c3, c1 | c2 | c3. spritecheck.py accepts indexed images with a previously optimised palette only.

./spritecheck.py -c 2 spritesheet.png

Help message

usage: spritecheck.py [-h] [--version] [-c MAX_SPRITES] [-t TRANS_COLOR] image

Sprite Checker for MSX2 sprites

positional arguments:
  image                 image to examine

options:
  -h, --help            show this help message and exit
  --version             show program's version number and exit
  -c MAX_SPRITES, --count MAX_SPRITES
                        maximum sprites per slot (default: 2)
  -t TRANS_COLOR, --trans TRANS_COLOR
                        define transparent color (default: 000000)

Copyright (C) 2023 Pedro de Medeiros <pedro.medeiros@.gmail.com>

TODO

For png2sprites.py:

• palette export feature;
• palette optimizations to reduce sprite count;
• make palette file optional;
• add an option to optimise away palette file;
• make palette minimisation faster;

For spritecheck.py:

• allow user to somehow specify where in the image the sprites are by (x, y) coordinates;
• create a copy of the original sprite sheet pointing out where the sprite conversion failed;