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Adding Multi region Support
Josh edited this page May 25, 2021
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When making a hack, you may want the player to visit more than one region and with how Pokémon Emerald is set up, there is no way of identifying the region.
This tutorial will walk you through how to add the support for multiple regions through the available mapsection IDs. How to do this is simple.
Firstly, we need to open src/overworld.c as there are two functions we need to change.
Find LoadCurrentMapData and make the following change:
static void LoadCurrentMapData(void)
{
sLastMapSectionId = gMapHeader.regionMapSectionId;
gMapHeader = *Overworld_GetMapHeaderByGroupAndId(gSaveBlock1Ptr->location.mapGroup, gSaveBlock1Ptr->location.mapNum);
gSaveBlock1Ptr->mapLayoutId = gMapHeader.mapLayoutId;
gMapHeader.mapLayout = GetMapLayout();
+ gMapHeader.region = sMapsecToRegion[gMapHeader.regionMapSectionId];
}This function handles the loading of the data for the currently loaded map.
Right below that function, there is LoadSaveblockMapHeader, which handles loading the respective map data on save resume. We need to make the following change:
static void LoadSaveblockMapHeader(void)
{
gMapHeader = *Overworld_GetMapHeaderByGroupAndId(gSaveBlock1Ptr->location.mapGroup, gSaveBlock1Ptr->location.mapNum);
gMapHeader.mapLayout = GetMapLayout();
+ gMapHeader.region = sMapsecToRegion[gMapHeader.regionMapSectionId];
}If you've noticed, we've added gMapHeader.region which loads data in sMapsecToRegion which we will be covering.
Next, we need to open include/global.fieldmap.h and find the struct MapHeader which should look like this:
struct MapHeader
{
/* 0x00 */ const struct MapLayout *mapLayout;
/* 0x04 */ const struct MapEvents *events;
/* 0x08 */ const u8 *mapScripts;
/* 0x0C */ const struct MapConnections *connections;
/* 0x10 */ u16 music;
/* 0x12 */ u16 mapLayoutId;
/* 0x14 */ u8 regionMapSectionId;
/* 0x15 */ u8 cave;
/* 0x16 */ u8 weather;
/* 0x17 */ u8 mapType;
/* 0x18 */ u8 filler_18[2];
/* 0x1A */ u8 flags;
/* 0x1B */ u8 battleType;
};u8 filler_18[2] is our point of interest here as it's simply used for padding the struct by two bytes. We will be using one of those bytes for our own region byte, like so:
struct MapHeader
{
/* 0x00 */ const struct MapLayout *mapLayout;
/* 0x04 */ const struct MapEvents *events;
/* 0x08 */ const u8 *mapScripts;
/* 0x0C */ const struct MapConnections *connections;
/* 0x10 */ u16 music;
/* 0x12 */ u16 mapLayoutId;
/* 0x14 */ u8 regionMapSectionId;
/* 0x15 */ u8 cave;
/* 0x16 */ u8 weather;
/* 0x17 */ u8 mapType;
- /* 0x18 */ u8 filler_18[2];
+ /* 0x18 */ u8 filler_18;
+ /* 0x19 */ u8 region;
/* 0x1A */ u8 flags;
/* 0x1B */ u8 battleType;
};Now, we are going to be adding a new array that will be used for our new region field. For the sake of this tutorial, we will be using Hoenn, Kanto and the Sevii Islands. Open include/overworld.h and add the following:
+enum {
+ REGION_HOENN,
+ REGION_KANTO,
+ REGION_SEVII
+};These are IDs for the different regions with REGION_HOENN being 0, REGION_KANTO being 1 and REGION_SEVII being 2.
We are now going to add the array.
I prefer to put this into its own file, but you need to have the following somewhere in src/overworld.c:
+static const u8 sMapsecToRegion[] = {
+ [MAPSEC_LITTLEROOT_TOWN] = REGION_HOENN,
+ [MAPSEC_OLDALE_TOWN] = REGION_HOENN,
+ [MAPSEC_DEWFORD_TOWN] = REGION_HOENN,
+ [MAPSEC_LAVARIDGE_TOWN] = REGION_HOENN,
+ [MAPSEC_FALLARBOR_TOWN] = REGION_HOENN,
+ [MAPSEC_VERDANTURF_TOWN] = REGION_HOENN,
+ [MAPSEC_PACIFIDLOG_TOWN] = REGION_HOENN,
+ [MAPSEC_PETALBURG_CITY] = REGION_HOENN,
+ [MAPSEC_SLATEPORT_CITY] = REGION_HOENN,
+ [MAPSEC_MAUVILLE_CITY] = REGION_HOENN,
+ [MAPSEC_RUSTBORO_CITY] = REGION_HOENN,
+ [MAPSEC_FORTREE_CITY] = REGION_HOENN,
+ [MAPSEC_LILYCOVE_CITY] = REGION_HOENN,
+ [MAPSEC_MOSSDEEP_CITY] = REGION_HOENN,
+ [MAPSEC_SOOTOPOLIS_CITY] = REGION_HOENN,
+ [MAPSEC_EVER_GRANDE_CITY] = REGION_HOENN,
+ [MAPSEC_ROUTE_101] = REGION_HOENN,
+ [MAPSEC_ROUTE_102] = REGION_HOENN,
+ [MAPSEC_ROUTE_103] = REGION_HOENN,
+ [MAPSEC_ROUTE_104] = REGION_HOENN,
+ [MAPSEC_ROUTE_105] = REGION_HOENN,
+ [MAPSEC_ROUTE_106] = REGION_HOENN,
+ [MAPSEC_ROUTE_107] = REGION_HOENN,
+ [MAPSEC_ROUTE_108] = REGION_HOENN,
+ [MAPSEC_ROUTE_109] = REGION_HOENN,
+ [MAPSEC_ROUTE_110] = REGION_HOENN,
+ [MAPSEC_ROUTE_111] = REGION_HOENN,
+ [MAPSEC_ROUTE_112] = REGION_HOENN,
+ [MAPSEC_ROUTE_113] = REGION_HOENN,
+ [MAPSEC_ROUTE_114] = REGION_HOENN,
+ [MAPSEC_ROUTE_115] = REGION_HOENN,
+ [MAPSEC_ROUTE_116] = REGION_HOENN,
+ [MAPSEC_ROUTE_117] = REGION_HOENN,
+ [MAPSEC_ROUTE_118] = REGION_HOENN,
+ [MAPSEC_ROUTE_119] = REGION_HOENN,
+ [MAPSEC_ROUTE_120] = REGION_HOENN,
+ [MAPSEC_ROUTE_121] = REGION_HOENN,
+ [MAPSEC_ROUTE_122] = REGION_HOENN,
+ [MAPSEC_ROUTE_123] = REGION_HOENN,
+ [MAPSEC_ROUTE_124] = REGION_HOENN,
+ [MAPSEC_ROUTE_125] = REGION_HOENN,
+ [MAPSEC_ROUTE_126] = REGION_HOENN,
+ [MAPSEC_ROUTE_127] = REGION_HOENN,
+ [MAPSEC_ROUTE_128] = REGION_HOENN,
+ [MAPSEC_ROUTE_129] = REGION_HOENN,
+ [MAPSEC_ROUTE_130] = REGION_HOENN,
+ [MAPSEC_ROUTE_131] = REGION_HOENN,
+ [MAPSEC_ROUTE_132] = REGION_HOENN,
+ [MAPSEC_ROUTE_133] = REGION_HOENN,
+ [MAPSEC_ROUTE_134] = REGION_HOENN,
+ [MAPSEC_UNDERWATER_124] = REGION_HOENN,
+ [MAPSEC_UNDERWATER_126] = REGION_HOENN,
+ [MAPSEC_UNDERWATER_127] = REGION_HOENN,
+ [MAPSEC_UNDERWATER_128] = REGION_HOENN,
+ [MAPSEC_UNDERWATER_SOOTOPOLIS] = REGION_HOENN,
+ [MAPSEC_GRANITE_CAVE] = REGION_HOENN,
+ [MAPSEC_MT_CHIMNEY] = REGION_HOENN,
+ [MAPSEC_SAFARI_ZONE] = REGION_HOENN,
+ [MAPSEC_BATTLE_FRONTIER] = REGION_HOENN,
+ [MAPSEC_PETALBURG_WOODS] = REGION_HOENN,
+ [MAPSEC_RUSTURF_TUNNEL] = REGION_HOENN,
+ [MAPSEC_ABANDONED_SHIP] = REGION_HOENN,
+ [MAPSEC_NEW_MAUVILLE] = REGION_HOENN,
+ [MAPSEC_METEOR_FALLS] = REGION_HOENN,
+ [MAPSEC_METEOR_FALLS2] = REGION_HOENN,
+ [MAPSEC_MT_PYRE] = REGION_HOENN,
+ [MAPSEC_AQUA_HIDEOUT_OLD] = REGION_HOENN,
+ [MAPSEC_SHOAL_CAVE] = REGION_HOENN,
+ [MAPSEC_SEAFLOOR_CAVERN] = REGION_HOENN,
+ [MAPSEC_UNDERWATER_SEAFLOOR_CAVERN] = REGION_HOENN,
+ [MAPSEC_VICTORY_ROAD] = REGION_HOENN,
+ [MAPSEC_MIRAGE_ISLAND] = REGION_HOENN,
+ [MAPSEC_CAVE_OF_ORIGIN] = REGION_HOENN,
+ [MAPSEC_SOUTHERN_ISLAND] = REGION_HOENN,
+ [MAPSEC_FIERY_PATH] = REGION_HOENN,
+ [MAPSEC_FIERY_PATH2] = REGION_HOENN,
+ [MAPSEC_JAGGED_PASS] = REGION_HOENN,
+ [MAPSEC_JAGGED_PASS2] = REGION_HOENN,
+ [MAPSEC_SEALED_CHAMBER] = REGION_HOENN,
+ [MAPSEC_UNDERWATER_SEALED_CHAMBER] = REGION_HOENN,
+ [MAPSEC_SCORCHED_SLAB] = REGION_HOENN,
+ [MAPSEC_ISLAND_CAVE] = REGION_HOENN,
+ [MAPSEC_DESERT_RUINS] = REGION_HOENN,
+ [MAPSEC_ANCIENT_TOMB] = REGION_HOENN,
+ [MAPSEC_INSIDE_OF_TRUCK] = REGION_HOENN,
+ [MAPSEC_SKY_PILLAR] = REGION_HOENN,
+ [MAPSEC_SECRET_BASE] = REGION_HOENN,
+ [MAPSEC_DYNAMIC] = REGION_HOENN,
+ [MAPSEC_PALLET_TOWN] = REGION_KANTO,
+ [MAPSEC_VIRIDIAN_CITY] = REGION_KANTO,
+ [MAPSEC_PEWTER_CITY] = REGION_KANTO,
+ [MAPSEC_CERULEAN_CITY] = REGION_KANTO,
+ [MAPSEC_LAVENDER_TOWN] = REGION_KANTO,
+ [MAPSEC_VERMILION_CITY] = REGION_KANTO,
+ [MAPSEC_CELADON_CITY] = REGION_KANTO,
+ [MAPSEC_FUCHSIA_CITY] = REGION_KANTO,
+ [MAPSEC_CINNABAR_ISLAND] = REGION_KANTO,
+ [MAPSEC_INDIGO_PLATEAU] = REGION_KANTO,
+ [MAPSEC_SAFFRON_CITY] = REGION_KANTO,
+ [MAPSEC_ROUTE_4_FLYDUP] = REGION_KANTO,
+ [MAPSEC_ROUTE_10_FLYDUP] = REGION_KANTO,
+ [MAPSEC_ROUTE_1] = REGION_KANTO,
+ [MAPSEC_ROUTE_2] = REGION_KANTO,
+ [MAPSEC_ROUTE_3] = REGION_KANTO,
+ [MAPSEC_ROUTE_4] = REGION_KANTO,
+ [MAPSEC_ROUTE_5] = REGION_KANTO,
+ [MAPSEC_ROUTE_6] = REGION_KANTO,
+ [MAPSEC_ROUTE_7] = REGION_KANTO,
+ [MAPSEC_ROUTE_8] = REGION_KANTO,
+ [MAPSEC_ROUTE_9] = REGION_KANTO,
+ [MAPSEC_ROUTE_10] = REGION_KANTO,
+ [MAPSEC_ROUTE_11] = REGION_KANTO,
+ [MAPSEC_ROUTE_12] = REGION_KANTO,
+ [MAPSEC_ROUTE_13] = REGION_KANTO,
+ [MAPSEC_ROUTE_14] = REGION_KANTO,
+ [MAPSEC_ROUTE_15] = REGION_KANTO,
+ [MAPSEC_ROUTE_16] = REGION_KANTO,
+ [MAPSEC_ROUTE_17] = REGION_KANTO,
+ [MAPSEC_ROUTE_18] = REGION_KANTO,
+ [MAPSEC_ROUTE_19] = REGION_KANTO,
+ [MAPSEC_ROUTE_20] = REGION_KANTO,
+ [MAPSEC_ROUTE_21] = REGION_KANTO,
+ [MAPSEC_ROUTE_22] = REGION_KANTO,
+ [MAPSEC_ROUTE_23] = REGION_KANTO,
+ [MAPSEC_ROUTE_24] = REGION_KANTO,
+ [MAPSEC_ROUTE_25] = REGION_KANTO,
+ [MAPSEC_VIRIDIAN_FOREST] = REGION_KANTO,
+ [MAPSEC_MT_MOON] = REGION_KANTO,
+ [MAPSEC_S_S_ANNE] = REGION_KANTO,
+ [MAPSEC_UNDERGROUND_PATH] = REGION_KANTO,
+ [MAPSEC_UNDERGROUND_PATH_2] = REGION_KANTO,
+ [MAPSEC_DIGLETTS_CAVE] = REGION_KANTO,
+ [MAPSEC_KANTO_VICTORY_ROAD] = REGION_KANTO,
+ [MAPSEC_ROCKET_HIDEOUT] = REGION_KANTO,
+ [MAPSEC_SILPH_CO] = REGION_KANTO,
+ [MAPSEC_POKEMON_MANSION] = REGION_KANTO,
+ [MAPSEC_KANTO_SAFARI_ZONE] = REGION_KANTO,
+ [MAPSEC_POKEMON_LEAGUE] = REGION_KANTO,
+ [MAPSEC_ROCK_TUNNEL] = REGION_KANTO,
+ [MAPSEC_SEAFOAM_ISLANDS] = REGION_KANTO,
+ [MAPSEC_POKEMON_TOWER] = REGION_KANTO,
+ [MAPSEC_CERULEAN_CAVE] = REGION_KANTO,
+ [MAPSEC_POWER_PLANT] = REGION_KANTO,
+ [MAPSEC_ONE_ISLAND] = REGION_SEVII,
+ [MAPSEC_TWO_ISLAND] = REGION_SEVII,
+ [MAPSEC_THREE_ISLAND] = REGION_SEVII,
+ [MAPSEC_FOUR_ISLAND] = REGION_SEVII,
+ [MAPSEC_FIVE_ISLAND] = REGION_SEVII,
+ [MAPSEC_SEVEN_ISLAND] = REGION_SEVII,
+ [MAPSEC_SIX_ISLAND] = REGION_SEVII,
+ [MAPSEC_KINDLE_ROAD] = REGION_SEVII,
+ [MAPSEC_TREASURE_BEACH] = REGION_SEVII,
+ [MAPSEC_CAPE_BRINK] = REGION_SEVII,
+ [MAPSEC_BOND_BRIDGE] = REGION_SEVII,
+ [MAPSEC_THREE_ISLE_PORT] = REGION_SEVII,
+ [MAPSEC_SEVII_ISLE_6] = REGION_SEVII,
+ [MAPSEC_SEVII_ISLE_7] = REGION_SEVII,
+ [MAPSEC_SEVII_ISLE_8] = REGION_SEVII,
+ [MAPSEC_SEVII_ISLE_9] = REGION_SEVII,
+ [MAPSEC_RESORT_GORGEOUS] = REGION_SEVII,
+ [MAPSEC_WATER_LABYRINTH] = REGION_SEVII,
+ [MAPSEC_FIVE_ISLE_MEADOW] = REGION_SEVII,
+ [MAPSEC_MEMORIAL_PILLAR] = REGION_SEVII,
+ [MAPSEC_OUTCAST_ISLAND] = REGION_SEVII,
+ [MAPSEC_GREEN_PATH] = REGION_SEVII,
+ [MAPSEC_WATER_PATH] = REGION_SEVII,
+ [MAPSEC_RUIN_VALLEY] = REGION_SEVII,
+ [MAPSEC_TRAINER_TOWER] = REGION_SEVII,
+ [MAPSEC_CANYON_ENTRANCE] = REGION_SEVII,
+ [MAPSEC_SEVAULT_CANYON] = REGION_SEVII,
+ [MAPSEC_TANOBY_RUINS] = REGION_SEVII,
+ [MAPSEC_SEVII_ISLE_22] = REGION_SEVII,
+ [MAPSEC_SEVII_ISLE_23] = REGION_SEVII,
+ [MAPSEC_SEVII_ISLE_24] = REGION_SEVII,
+ [MAPSEC_NAVEL_ROCK_FRLG] = REGION_SEVII,
+ [MAPSEC_MT_EMBER] = REGION_SEVII,
+ [MAPSEC_BERRY_FOREST] = REGION_SEVII,
+ [MAPSEC_ICEFALL_CAVE] = REGION_SEVII,
+ [MAPSEC_ROCKET_WAREHOUSE] = REGION_SEVII,
+ [MAPSEC_TRAINER_TOWER_2] = REGION_SEVII,
+ [MAPSEC_DOTTED_HOLE] = REGION_SEVII,
+ [MAPSEC_LOST_CAVE] = REGION_SEVII,
+ [MAPSEC_PATTERN_BUSH] = REGION_SEVII,
+ [MAPSEC_ALTERING_CAVE_FRLG] = REGION_SEVII,
+ [MAPSEC_TANOBY_CHAMBERS] = REGION_SEVII,
+ [MAPSEC_THREE_ISLE_PATH] = REGION_SEVII,
+ [MAPSEC_TANOBY_KEY] = REGION_SEVII,
+ [MAPSEC_BIRTH_ISLAND_FRLG] = REGION_SEVII,
+ [MAPSEC_MONEAN_CHAMBER] = REGION_SEVII,
+ [MAPSEC_LIPTOO_CHAMBER] = REGION_SEVII,
+ [MAPSEC_WEEPTH_CHAMBER] = REGION_SEVII,
+ [MAPSEC_DILFORD_CHAMBER] = REGION_SEVII,
+ [MAPSEC_SCUFIB_CHAMBER] = REGION_SEVII,
+ [MAPSEC_RIXY_CHAMBER] = REGION_SEVII,
+ [MAPSEC_VIAPOIS_CHAMBER] = REGION_SEVII,
+ [MAPSEC_EMBER_SPA] = REGION_SEVII,
+ [MAPSEC_SPECIAL_AREA] = REGION_KANTO,
+ [MAPSEC_AQUA_HIDEOUT] = REGION_HOENN,
+ [MAPSEC_MAGMA_HIDEOUT] = REGION_HOENN,
+ [MAPSEC_MIRAGE_TOWER] = REGION_HOENN,
+ [MAPSEC_BIRTH_ISLAND] = REGION_SEVII,
+ [MAPSEC_FARAWAY_ISLAND] = REGION_HOENN,
+ [MAPSEC_ARTISAN_CAVE] = REGION_HOENN,
+ [MAPSEC_MARINE_CAVE] = REGION_HOENN,
+ [MAPSEC_UNDERWATER_MARINE_CAVE] = REGION_HOENN,
+ [MAPSEC_TERRA_CAVE] = REGION_HOENN,
+ [MAPSEC_UNDERWATER_105] = REGION_HOENN,
+ [MAPSEC_UNDERWATER_125] = REGION_HOENN,
+ [MAPSEC_UNDERWATER_129] = REGION_HOENN,
+ [MAPSEC_DESERT_UNDERPASS] = REGION_HOENN,
+ [MAPSEC_ALTERING_CAVE] = REGION_HOENN,
+ [MAPSEC_NAVEL_ROCK] = REGION_SEVII,
+ [MAPSEC_TRAINER_HILL] = REGION_HOENN
+};Don't forget to declare it somewhere in src/overworld.c like so:
+static const u8 sMapsecToRegion[];If I explained this correctly and didn't miss anything out, you should be able to compile the changes using make and the game will now use the region field for the current map the player is on.
With this, you can do things like add battle music that changes depending on the region the player is in. I will update this tutorial at some point with how you can do this.