Slightly on the Wild Side

So.. I spent all night looking at the sprites, it’s 7am now.. I should probably get some sleep

There is a video to go with this too… didn’t have time to do it last night

Anyway, as discussed before the game uses compressed sprites. The actual compression isn’t TOO complex, it’s just several RLE modes in the end (although the current implementation is still incomplete, many sprites have holes, and I don’t know if the palettes are encoded in there too)

The main issue is the weird arrangement of the ROMs, the compression works on 10-bits at a time, which is unusual, and means that the game actually has 10 sprite roms, which need to be correctly ordered and divided up to get the right data to process.

One area Cool Riders differs to practically every other Sega game is that the sprites are actually TILE based, every sprite is made of a number of 16×16 tiles, and the layout of these tiles for each sprite is also stored in the compressed graphics roms. The spritelist actually references a tile arrangement in these roms, with that tile arrangement further referencing the compressed data located at some position after it (allowing for the same compressed data to be shared with multiple tile arrangements)

Anyway, for now the temp zoom code is gone, so you can see things break up quite badly in the video, and the lack of flipping becomes VERY obvious now we have somewhat correct sprite data. Improving these is on my todo list. Likewise I still need to figure out where the framebuffer clear bits are because right now it flickers badly, it’s migraine inducing.

Here is a video from yesterday with temp zoom code reinstated, some stupid bugs with flipped-zoomed sprites that have since been fixed tho.