Set Metatile IDs From Another Map

Set Metatile IDs from Another Map

credit to ghoulslash

Step 1

Open fieldmap.c and add this function somewhere:

extern void DrawWholeMapView(void);
void CopyMetatileIdsFromMapLayout(u16 mapGroup, u16 mapNum, const u8 pos[][2])
{
    u32 i, block, x, y;
    struct MapLayout const *layout = Overworld_GetMapHeaderByGroupAndId(mapGroup, mapNum)->mapLayout;
    
    i = 0;
    do {
        x = pos[i][0];
        y = pos[i][1];
        block = layout->map[x + layout->width * y];
        MapGridSetMetatileIdAt(x + MAP_OFFSET, y + MAP_OFFSET, block);
        i++;
    } while (pos[i][0] != 0xFF);

    DrawWholeMapView();
}

It works by taking a map group and number and array of (x,y) positions and copies them into the current map from the given layout. An example of the pos argument:

• If I want to copy the first 2 columns of a map from y positions 0 through 7:

static const u8 sTestPositions[][2] = {
    {0, 0}, {0, 1}, {0, 2}, {0, 3}, {0, 4}, {0, 5}, {0, 6}, {0, 7},
    {1, 0}, {1, 1}, {1, 2}, {1, 3}, {1, 4}, {1, 5}, {1, 6}, {1, 7},
    {0xFF, 0xFF}, // to signify the end of the array
};

• So we would call the above with CopyMetatileIdsFromMapLayout(<map map group>, <my map num>, sTestPositions);