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[Map✓] "Map Swap" glitch

Child Amnesiac

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    Hi, while Bug testing I ran across this glitch that seems to swap out maps for other maps for some reason.

    [PokeCommunity.com] "Map Swap" glitch


    The map itself is a gym from later in the game, but the events seem to be the same as the map that's supposed to load.
    The map this one and all other Gym maps replace is the upstairs for the Pokemon center, so could that be causing it?
    Other maps seem to swap with other maps too.

    What going on here? Is it ROM corruption? How can I fix this, (if I can fix this)?
     
    Last edited:
    Yeah, that's a pretty common thing that happens, but thankfully its not due to corruption. Those maps share a 'Map ID'. The Map ID is a halfword in the map header that tells the game which map (not events) to load, but if two maps share the same ID, one can load instead of the other. You can check out this thread by Spherical Ice for some more info. Anyway, to fix this, all you have to do is change the map IDs of the interlocked maps. The Map ID is determined by the 19th and 20th bytes in the map header. For example, here's the Map Header of Pallet Town with its Map ID underlined:

    Code:
    C0D42D08504E3B085A5416086C2735082C01[U]4E00[/U]5800020101060000

    If you were to change those bytes to 4F 00, you may load Viridian City instead. These can't be changed in Advance Map on the fly, so you'll have to open your ROM in a Hex Editor and change the header data through that instead. I went through the game a long time ago and recorded every map's Map ID based on Spherical Ice's initial data, so feel free to use it to know which specific maps are linked with each other.
     
    Yeah, that's a pretty common thing that happens, but thankfully its not due to corruption. Those maps share a 'Map ID'. The Map ID is a halfword in the map header that tells the game which map (not events) to load, but if two maps share the same ID, one can load instead of the other. You can check out this thread by Spherical Ice for some more info. Anyway, to fix this, all you have to do is change the map IDs of the interlocked maps. The Map ID is determined by the 19th and 20th bytes in the map header. For example, here's the Map Header of Pallet Town with its Map ID underlined:

    Code:
    C0D42D08504E3B085A5416086C2735082C01[U]4E00[/U]5800020101060000

    If you were to change those bytes to 4F 00, you may load Viridian City instead. These can't be changed in Advance Map on the fly, so you'll have to open your ROM in a Hex Editor and change the header data through that instead. I went through the game a long time ago and recorded every map's Map ID based on Spherical Ice's initial data, so feel free to use it to know which specific maps are linked with each other.

    Hey, thanks.

    This has been a huge problem for me, and now I think I can fix it.

    Edit: No, it just caused another problem.
    You can't move, and the map looks like this:

    [PokeCommunity.com] "Map Swap" glitch


    I used an unused ID, should I not have done that?

    Edit 2: I found a solution.
    Create a dummy version of the map on an unused map, and set the ID to that map.
     
    Last edited:
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