Triple layer metatiles - pret/pokefirered GitHub Wiki

This is an adaptation of the tutorial found on the pokeemerald wiki. Most of the changes found in the original post can applied to pokefirered, however some changes are necessary.

DrawMetatile in src/field_camera.c

Fire Red is a little fucked up in that the top, middle, and bottom layers are not written to the background layers of 3, 2, and 1 respectively the same way it is in Emerald. Instead, it seems like layers 2 and 1 are switched. Like so:

• Background 3 - Bottom Layer
• Background 1 - Middle Layer
• Background 2 - Top Layer

As such, when editing the DrawMetatile function, the correct way to reflect the triple layers is like so:

static void DrawMetatile(s32 metatileLayerType, const u16 *tiles, u16 offset)
{
    if (metatileLayerType == 0xFF)
    {
        // A door metatile shall be drawn, we use covered behavior
        // Draw metatile's bottom layer to the bottom background layer.
        gOverworldTilemapBuffer_Bg3[offset] = tiles[0];
        gOverworldTilemapBuffer_Bg3[offset + 1] = tiles[1];
        gOverworldTilemapBuffer_Bg3[offset + 0x20] = tiles[2];
        gOverworldTilemapBuffer_Bg3[offset + 0x21] = tiles[3];

        // Draw transparent tiles to the top background layer.
        gOverworldTilemapBuffer_Bg1[offset] = 0;
        gOverworldTilemapBuffer_Bg1[offset + 1] = 0;
        gOverworldTilemapBuffer_Bg1[offset + 0x20] = 0;
        gOverworldTilemapBuffer_Bg1[offset + 0x21] = 0;

        // Draw metatile's top layer to the middle background layer.
        gOverworldTilemapBuffer_Bg2[offset] = tiles[4];
        gOverworldTilemapBuffer_Bg2[offset + 1] = tiles[5];
        gOverworldTilemapBuffer_Bg2[offset + 0x20] = tiles[6];
        gOverworldTilemapBuffer_Bg2[offset + 0x21] = tiles[7];

    }
    else
    {
        // Draw metatile's bottom layer to the bottom background layer.
        gOverworldTilemapBuffer_Bg3[offset] = tiles[0];
        gOverworldTilemapBuffer_Bg3[offset + 1] = tiles[1];
        gOverworldTilemapBuffer_Bg3[offset + 0x20] = tiles[2];
        gOverworldTilemapBuffer_Bg3[offset + 0x21] = tiles[3];

        // Draw metatile's middle layer to the middle background layer.
        gOverworldTilemapBuffer_Bg1[offset] = tiles[4];
        gOverworldTilemapBuffer_Bg1[offset + 1] = tiles[5];
        gOverworldTilemapBuffer_Bg1[offset + 0x20] = tiles[6];
        gOverworldTilemapBuffer_Bg1[offset + 0x21] = tiles[7];

        // Draw metatile's top layer to the top background layer, which covers object event sprites.
        gOverworldTilemapBuffer_Bg2[offset] = tiles[8];
        gOverworldTilemapBuffer_Bg2[offset + 1] = tiles[9];
        gOverworldTilemapBuffer_Bg2[offset + 0x20] = tiles[10];
        gOverworldTilemapBuffer_Bg2[offset + 0x21] = tiles[11];


    }
    
    ScheduleBgCopyTilemapToVram(1);
    ScheduleBgCopyTilemapToVram(2);
    ScheduleBgCopyTilemapToVram(3);
}

BuyMenuDrawMapMetatile

Which TilemapBuffers to write to are different in Fire Red, copy the function below instead:

static void BuyMenuDrawMapMetatile(s16 x, s16 y, const u16 *src, u8 metatileLayerType)
{
    u16 offset1 = x * 2;
    u16 offset2 = y * 64 + 64;

    if (metatileLayerType == METATILE_LAYER_TYPE_NORMAL)
    {
        BuyMenuDrawMapMetatileLayer(*gShopTilemapBuffer3, offset1, offset2, src + 0);
        BuyMenuDrawMapMetatileLayer(*gShopTilemapBuffer4, offset1, offset2, src + 4);
        BuyMenuDrawMapMetatileLayer(*gShopTilemapBuffer2, offset1, offset2, src + 8);
    }
    else
    {
        if (IsMetatileLayerEmpty(src))
        {
            BuyMenuDrawMapMetatileLayer(*gShopTilemapBuffer4, offset1, offset2, src);
            BuyMenuDrawMapMetatileLayer(*gShopTilemapBuffer2, offset1, offset2, src + 4);
        }
        else if (IsMetatileLayerEmpty(src + 4))
        {
            BuyMenuDrawMapMetatileLayer(*gShopTilemapBuffer3, offset1, offset2, src);
            BuyMenuDrawMapMetatileLayer(*gShopTilemapBuffer4, offset1, offset2, src + 4);
        }
        else if (IsMetatileLayerEmpty(src + 8))
        {
            BuyMenuDrawMapMetatileLayer(*gShopTilemapBuffer3, offset1, offset2, src);
            BuyMenuDrawMapMetatileLayer(*gShopTilemapBuffer2, offset1, offset2, src + 4);
        }
    }
}
}

Python Script

When you get to the part about using the python script, use this python script c/o snaid instead: https://gist.github.com/Snaid1/634847353fd320ea24aa71271afb9cde