Sprite compression (Generation I): Difference between revisions
Jump to navigation
Jump to search
Content added Content deleted
No edit summary |
No edit summary |
||
| Line 1: | Line 1: | ||
{{incomplete|needs proper analysis. The official method may also have been in the source code}} |
{{incomplete|needs proper analysis. The official method may also have been in the source code}} |
||
'''Sprite compression''' is the means in Generation I for where pure graphics data is compressed into a Pokémon or Trainer sprite. The sprite is decompressed again using [[Sprite decompression (Generation I)|the sprite decompression routine]]. While the source compressor code is not in the ROMs; there are a few rules for a compressed sprite: |
'''Sprite compression''' is the means in Generation I for where pure graphics data is compressed into a Pokémon or Trainer sprite. The sprite is decompressed again using [[Sprite decompression (Generation I)|the sprite decompression routine]] and allocates use of unbanked SRAM. While the source compressor code is not in the ROMs; there are a few rules for a compressed sprite: |
||
*The image to compress is usually a maximum of 56x56 pixels. Other Pokémon sprites can be 32x32, 40x40 or 48x48. |
*The image to compress is usually a maximum of 56x56 pixels. Other Pokémon sprites can be 32x32, 40x40 or 48x48. |
||
| Line 9: | Line 9: | ||
*Unofficially, a .2bpp file can be converted into a compressed Pokémon sprite using the tool pkmncompress, and a .PNG into a compatible .2bpp file using rgbds. "Sprite import tools for RBY" can be downloaded within Evie's Google Sites backup [https://drive.google.com/drive/folders/1DAVPYay9sAuXwi4qXbDQfPU2sIDI_mXH?usp=sharing here] (based on the previous work of the GB Dev and Skeetendo communities). |
*Unofficially, a .2bpp file can be converted into a compressed Pokémon sprite using the tool pkmncompress, and a .PNG into a compatible .2bpp file using rgbds. "Sprite import tools for RBY" can be downloaded within Evie's Google Sites backup [https://drive.google.com/drive/folders/1DAVPYay9sAuXwi4qXbDQfPU2sIDI_mXH?usp=sharing here] (based on the previous work of the GB Dev and Skeetendo communities). |
||
*It is possible for the sprite to be flipped for a non-00 value in memory address 0xD0AA ([[Pokémon Red and Blue]]) or 0xD0A9 ([[Pokémon Yellow]]). The [[inverse sprites glitch]] corrupts these memory addresses, possibly leading to glitched sprites. |
*It is possible for the sprite to be flipped for a non-00 value in memory address 0xD0AA ([[Pokémon Red and Blue]]) or 0xD0A9 ([[Pokémon Yellow]]). The [[inverse sprites glitch]] corrupts these memory addresses, possibly leading to glitched sprites. |
||
Unintended compressed sprites with dimensions of 0 are known for their memory overflows, such as Yellow [[MissingNo.]]'s sprite (treated as dimensions of 256, or (256/8)=32). |
Unintended compressed sprites with dimensions of 0 are known for their memory overflows, such as Yellow [[MissingNo.]]'s sprite (treated as dimensions of 256, or (256/8)=32). |
||