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Old 08-07-2019, 10:53 PM   #1
Eskayelle
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Join Date: Jun 2017
Posts: 12
Default [HELP] Streets of Rage 2 Title Screen Hacking Questions

Hi. I'm currently experimenting with hacking title screens for Genesis, specifically Streets of Rage 2, so I'm looking for someone with Genesis assembly experience to provide a little guidance. I don't have much Genesis hacking experience, as I've spent the last few summers working with the SNES, but I have some idea of where I need to go.

1) I figure I'd first export the title screen via Pancake 2, but I'm not sure of the offset for the screen. Would anyone be able to help locate and provide this?

2) I'm next going to import that result into SonMapEd and try to figure out the tile mapping. Would anyone be able to help locate and provide the offset for the title screen's palette?

3) Having done this, I'm going to overlay my title screen onto the mapping and try to apply my title screen's palette, then export to .bin and drop that data into expanded rom. How many colors is the title screen limited to, 16 or 256?

4) I may need to add commands to expanded rom to display the title screen, plus re-route original code to that title screen. From portrait editing, I'm wondering if placing this code before the new title screen data will do the trick, [XX][YY][ZZ] being a relative pointer to the new title screen:

33 FC 81 3C 00 C0 00 04 23 FC 94 0E 93 A0 00 C0
00 04 23 FC 96 [YY] 95 [ZZ] 00 C0 00 04 33 FC 97 [XX]
00 C0 00 04 23 FC 60 00 00 81 00 C0 00 04 4E 75

5) With the new title screen in expanded rom, I need to point to it in the original code. Will the original pointer use code 41 F9 00 [AA][BB][CC], where [AA][BB][CC] is that offset I'm looking for in #1?

6) If #5 is yes, do I then change that code to be 4E B9 00 [DD][EE][FF], where [DD][EE][FF] is my offset in expanded rom that has the 33 FC... code per #4 above?

7) I assume the code I need for the pointer is around where the decompression algorithm is, similar to the portraits on the player select screen. Not positive of this though. And I just 4E 71 / NOP that decompression code?

Any questions you can help answer would be a huge help!
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