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Generation II Glitch Discussion

How may we create arbitrary sprites with ACE in Generation II? - Page 1

How may we create arbitrary sprites with ACE in Generation II?

Posted by: Torchickens
Date: 2019-01-28 06:33:35
https://glitchcity.info/wiki/Arbitrary_sprites

I want us to be able to do this with arbitrary code execution in Generation II but I'm unsure where to start, wondering if anyone has any ideas (would be much appreciated  :))? I checked the Egg's backsprite but I was under the impression it was sourced from ROM, however I could have been mistaken. Thanks in advance!

Re: How may we create arbitrary sprites with ACE in Generation II?

Posted by: Parzival
Date: 2019-01-28 07:34:29
Use a disasm to see where the sprite decompression routine is, then set an access breakpoint at the beginning of it in BGBto find the pointer to the backsprite.

Re: How may we create arbitrary sprites with ACE in Generation II?

Posted by: Torchickens
Date: 2019-01-28 08:21:12

Use a disasm to see where the sprite decompression routine is, then set an access breakpoint at the beginning of it in BGBto find the pointer to the backsprite.


Thanks for the input. I did something like that but I think it seemed Egg back was in ROM. By using the debugger it would be possible to change the registers though (but I was thinking more of a ACE method; with the debugger we can just edit VRAM).

Possibly maybe we could call the routine(s) to display a sprite (modified if necessary with a copy of it in RAM). As a last resort, we could call CopyData to write bytes into VRAM itself when it is unlocked.