GBA Code Request -Megaman Zero-

[gamefaqs99]

Hi, I wonder if someone knows how to change background position on GBA GAMES, specially Megaman Zero 1 for GBA:

for example when the stage loads, the default position for background is x=100 and y=100
needd to change those default values but the problem is that I can't found those addresses.
I've been searching for 30+hours this week but no luck..
if someon want a comi$$ion to find this I'm opened to make a deal.

thanks in advance

 

[FAST6191]

That is potentially a more advanced thing that cheats might struggle with.

Choice links
http://problemkaputt.de/gbatek.htm#lcdiobgscrolling
http://www.coranac.com/tonc/text/video.htm
https://www.cs.rit.edu/~tjh8300/CowBite/CowBiteSpec.htm#Graphics Hardware Overview

I would then get a debugging emulator (no$gba debug is free these days http://problemkaputt.de/gba.htm , others like mgba https://mgba.io/ , others still might still use the likes of vba-sdl-h https://web.archive.org/web/20130215155212/http://labmaster.bios.net.nz/vba-sdl-h/ https://www.romhacking.net/documents/361/ ) and set it on the relevant aspects of the LCD I/O BG Scrolling hardware noted above, whatever changes that between selecting a level and starting it should have some initial values.

That said looking at

Do you mean the character's placement in the middle of the screen is not to your liking? Central screen placement is a potentially questionable one ( https://docs.google.com/document/d/1iNSQIyNpVGHeak6isbP6AHdHD50gs8MNXF1GCf08efg/pub?embedded=true featuring games from long before this).
I might wonder if Ciel would go off screen if you are going to change that, plus bosses could be something, some enemies in that also came from behind and did not do the telegraphing thing noted in the link which might make the game harder, not to mention that desert mission around the 20 minute mark in the video that sees you going right to left. None of those are insurmountable but it is rapidly moving from change some initial values to something more complicated.

 

[gamefaqs99]

Thanks for take the time to gather all this documentation, your responde seems to be right, today I spent more hours searching one last time to be sure, but the value is not in the ram to be writable. "I'm almost sure"

About the camera: I was not looking for change the position of the player respectively to the center camera but since my search was a little in-depth, in fact, I found that value.
I changed zero to the left and ciel Still follow zero without problems , same for the right-center.
What I'm looking for is just to change the original X,Y position of the background, fortunately, no need to touch the camera.

This is a example of what I'm trying to achieve, just move the backgroun few pixels of it's default center
or move the green leaves of trees to the left.

in this image the backgroun was moved up few pixels with image edition. not changing values.

I readed the documents and you're right, it's really advanced.
it's like tryng create new stages just with cheats, it need a romhack tools.
I'll Keep searching and again, thanks for your help

 

[FAST6191]

Ah OK. Don't normally see parallax scrolling arty hacks for the GBA (compared to SNES, PCE/TG16 and megadrive where it a far more common concern).

In that case images are built up from layers (I presume you disabled the layers in an emulator and screengrabbed those individually beyond playing in the image editor to make your demo image there). In that case there are two main approaches.

1) Backgrounds are usually still tiles. They use something called maps to arrange said tiles to make the image seen on screen. If you only want to cut out a bit of sky then you could approach the mapping aspect. This is lesser considered in a lot of guides (including my own https://gbatemp.net/threads/gbatemp-rom-hacking-documentation-project-new-2016-edition-out.73394/ ) as it can be quite custom (and that is become background based animations come onto the scene*), even if it will stick close to what the hardware expects as there is precious little time/CPU resources available to be doing a pointless conversion. You can sometimes find these like you might with palettes (dump it from RAM, search ROM for it) and if you can get something like that.
There is also potentially the crazy man's genius cousin option of find the tiles that make that image and edit those, however this is not looking like a simple background where such things are more amenable to happening (if it was a basic banding/gradient type deal then it starts becoming easier).

*the desert mission at 52:30 minutes possibly having that to simulate a mirage effect, and the escape sequence at 30:30 possibly having it exaggerate the destruction/collapse.

2) The scrolling stuff I already mentioned. To get an idea of what goes here I usually point people at Tetris Worlds on the GBA. The main menu has a scrolling stars effect but if you actually look at the image it is larger than the GBA resolution and just flies around it in a pattern to create a zooming around effect. If something similar happened here (sometimes devs like to use it to make it look like falls are faster than they are as the background "bends" as it were, I mentioned the escape sequence above) then you can use that. This will however involve delving into the code.