TextureDump.java

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.lang.reflect.Field;
import java.nio.IntBuffer;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

import javax.imageio.ImageIO;

import org.lwjgl.BufferUtils;
import org.lwjgl.opengl.GL11;
import org.lwjgl.opengl.GL12;

import net.minecraft.client.renderer.texture.TextureMap;
import net.minecraftforge.client.event.TextureStitchEvent;
import net.minecraftforge.common.MinecraftForge;

import com.google.common.base.Function;
import com.google.common.primitives.Ints;

import cpw.mods.fml.common.FMLLog;
import cpw.mods.fml.common.Mod;
import cpw.mods.fml.common.Mod.EventHandler;
import cpw.mods.fml.common.event.FMLPreInitializationEvent;
import cpw.mods.fml.common.eventhandler.SubscribeEvent;

@Mod(modid = TextureDump.MODID, version = TextureDump.VERSION)
public class TextureDump
{
    public static final String MODID = "texture_dump";
    public static final String VERSION = "1.0";

    @EventHandler
    public void preInit(FMLPreInitializationEvent  event)
    {
        MinecraftForge.EVENT_BUS.register(this);
    }

    @SubscribeEvent
    public void postTextureStitch(TextureStitchEvent.Post e) throws Exception
    {
        saveGlTexture(getName(e.map), e.map.getGlTextureId(), getMip(e.map));

    }

    private static Field fName;
    private static String getName(TextureMap map) throws Exception
    {
        if (fName == null)
        {
            fName = TextureMap.class.getDeclaredFields()[7];
            fName.setAccessible(true);
        }
        return ((String)fName.get(map)).replace('/', '_');
    }
    private static Field fMip;
    private static int getMip(TextureMap map) throws Exception
    {
        if (fMip == null)
        {
            fMip = TextureMap.class.getDeclaredFields()[8];
            fMip.setAccessible(true);
        }
        return fMip.getInt(map);
    }


    public static void saveGlTexture(String name, int textureId, int mipmapLevels)
    {
        GL11.glBindTexture(GL11.GL_TEXTURE_2D, textureId);

        GL11.glPixelStorei(GL11.GL_PACK_ALIGNMENT, 1);
        GL11.glPixelStorei(GL11.GL_UNPACK_ALIGNMENT, 1);

        for (int level = 0; level <= mipmapLevels; level++)
        {
            int width = GL11.glGetTexLevelParameteri(GL11.GL_TEXTURE_2D, level, GL11.GL_TEXTURE_WIDTH);
            int height = GL11.glGetTexLevelParameteri(GL11.GL_TEXTURE_2D, level, GL11.GL_TEXTURE_HEIGHT);
            int size = width * height;

            BufferedImage bufferedimage = new BufferedImage(width, height, 2);
            File output = new File(name + "_" + level + ".png");

            IntBuffer buffer = BufferUtils.createIntBuffer(size);
            int[] data = new int[size];

            GL11.glGetTexImage(GL11.GL_TEXTURE_2D, level, GL12.GL_BGRA, GL12.GL_UNSIGNED_INT_8_8_8_8_REV, buffer);
            buffer.get(data);
            bufferedimage.setRGB(0, 0, width, height, data, 0, width);

            try
            {
                ImageIO.write(bufferedimage, "png", output);
                FMLLog.info("[TextureDump] Exported png to: {}", output.getAbsolutePath());
            }
            catch (IOException ioexception)
            {
                FMLLog.info("[TextureDump] Unable to write: ", ioexception);
            }
        }
    }
}