Acmlm's Board - I2 Archive - Rom Hacking - LttP technical question - "messed up" overlay maps
| User | Post |
Gideon Zhi
Posts: 36/79 |
Yeah, I saw that, but I've found that the problem with changing it is that it doesn't "stick."
If I set it to _always_ load #$9F, it'll work fine as I exit onto the overworld, but it'll change as soon as I move left/right/up/down into a different area. *grumble*
I'll figure it out, though. |
Euclid
Posts: 164/193 |
$02/B00B is about the same place (you'll have to scroll up a bit) where the game checks if any overlay should be loaded for a particular OV screen (earlier on you can see checks for "if the game is at beginning" and "is area 03,05 or 07 - mountain" or even if you're at 40 etc). |
Gideon Zhi
Posts: 35/79 |
Looks that way.
Alright though, I think I can deal with this. I'll just make do with what I've got 
[Edit] After tinkering with the code around 02/B00B, I've determined conclusively that the overlay is stored in both registers $8A -and- $8C after it goes through the whole area and event checking process. A backup of the current map index is chunked into $7EC213 for further use down the road.
This code -is- pretty nasty, but I think I can deal with it. |
Euclid
Posts: 163/193 |
I believe it goes like this:
Overworld areas has a 3 byte pointer (dont' ask me where it is, i've never looked), Those areas which are bugged up has pointers to Area 00 (because that is area 00 with palletes/gfx blocks stuffed up),
i have never thought about using them as more BG (since that BG routine is quite annoying to change with limited space), I'm sure the tilesets are there, i've never looked into how it works... maybe i should do so now since i'm a bit free.
EDIT:
After spending like 30 minutes on the debugger, i found out adding an overlay is like...very hard.
The Overlay used for each OV screen is stored in $8C, and a default value is always stored (i believe it's 9B),
Then at $02/BC01, where it actually checks for each overlay,
$02/BC01 A6 8C LDX $8C [$00:008C]
$02/BC03 E0 97 CPX #$97
$02/BC05 F0 59 BEQ $59 [$BC60]
$02/BC07 E0 9D CPX #$9D
$02/BC09 F0 55 BEQ $55 [$BC60]
it's pretty much doing one slab of code per overlay (note above, 97 and 9D are the same fog), i believe the overlay palettes and anything related to that overlay is added in that branch which you might want to look into.
but adding another overlay may be hard since HM won't like you adding stuff to those screens...
|
Gideon Zhi
Posts: 34/79 |
Well, I'm not planning on using it as more overworld space, but instead as more "background" space - like with the forest background, rain background, etc.
Also, the palette numbers in HM are greyed out for these maps. I'm specifically interested in tiddling with the palette for the fog, whereabouts in the ROM would I find this information? I know my way around a hex editor quite well, I just need an address :p |
SePH
Posts: 303/459 |
I once tried to use those areas and it didn't worked (Try to set an exit there and you'll see).
It doesn't seem to work as I can't find how to edit the tilesets. And also when you exit in one of those areas, Link seems to get stuck and you can't move him. Any help on this would be appreciated as I could use more overworld space. |
tuna
Posts: 309/2 |
Is this a fresh ROM? if so, that's really wierd. I've never seen that 
Make sure the ROM you use isn't corrupt, since that looks extremely weird. |
Ringodoggie
Posts: 191/281 |
I think those tiles are used for other areas such as Death Mountain. Either that or there are bugs in the editor (corrupted data) or they're unused. |
Gideon Zhi
Posts: 33/79 |
I'm looking at some of the overworld overlays and backgrounds in Hyrule Magic, but some of them are... well, I guess "buggered up" is probably the most accurate way to put it. Map 9B, for example. They contain, basically, junk data, and a number of them are duplicates. Are these safe to draw over? I'd like to try to use them for... other things. Cough cough, grin.
[Edit] Here's a screenshot of one of the maps I'm referring to (9B.)
 |
|
hukka
