2127df4dc7
- MapInfo should not be emitted - TilesInfo should have name shortened - Update test output
png2asset
A tool that converts png to maps or meta sprites in C for gbdk 2020
Working with png2asset
-
The origin (pivot) for the metasprite is not required to be in the upper left-hand corner as with regular hardware sprites. See
-pxand-py. -
The conversion process supports using both SPRITES_8x8 (
-spr8x8) and SPRITES_8x16 mode (-spr8x16). If 8x16 mode is used then the height of the metasprite must be a multiple of 16.
Terminology
The following abbreviations are used in this section:
- Original Game Boy and Game Boy Pocket style hardware:
DMG - Game Boy Color:
CGB
Conversion Process
png2asset accepts any png as input, although that does not mean any image will be valid. The program will follow the next steps:
- The image will be subdivided into tiles of 8x8 or 8x16
- For each tile a palette will be generated
- If there are more than 4 colors in the palette it will throw an error
- The palette will be sorted from darkest to lightest. If there is a transparent color that will be the first one (this will create a palette that will also work with
DMGdevices) - If there are more than 8 palettes the program will throw an error
With all this, the program will generate a new indexed image (with palette), where each 4 colors define a palette and all colors within a tile can only have colors from one of these palettes
It is also posible to pass an indexed 8-bit png with the palette properly sorted out, using -keep_palette_order
- Palettes will be extracted from the image palette in groups of 4 colors.
- Each tile can only have colors from one of these palettes per tile
- The maximum number of colors is 32
Using this image a tileset will be created
- Duplicated tiles will be removed
- Tiles will be matched without mirror, using vertical mirror, horizontal mirror or both (use
-noflipto turn off matching mirrored tiles) - The palette won't be taken into account for matching, only the pixel color order, meaning there will be a match between tiles using different palettes but looking identical on grayscale
Maps
Passing -map the png can be converted to a map that can be used in both the background and the window. In this case, png2asset will generate:
- The palettes
- The tileset
- The map
- The color info
- By default, an array of palette index for each tile. This is not the way the hardware works but it takes less space and will create maps compatibles with both
DMGandCGBdevices. - Passing
-use_map_attributeswill create an array of map attributes. It will also add mirroring info for each tile and because of that maps created with this won't be compatible with.- Use
-noflipto make background maps which are compatible withDMGdevices.
- Use
- By default, an array of palette index for each tile. This is not the way the hardware works but it takes less space and will create maps compatibles with both
Meta sprites
By default the png will be converted to metasprites. The image will be subdivided into meta sprites of -sw x -sh. In this case png2asset will generate:
- The metasprites, containing an array of:
- tile index
- y offset
- x offset
- flags, containing the mirror info, the palettes for both DMG and GBC and the sprite priority
- The metasprites array