I guess I solved the problem, just remove "ClassWriter.COMPUTE_FRAMES" when creating ClassWriter object and the error rooted from that line disappears. There are other problems left but I'll make another post as the cause(s) are quite different from this situation. (I think they are about how Forge load the mod and JAR structure)

 

=========================================

 

Hello, I'm making a coremod that replace current title screen (GuiMainMenu) with my own (GuiCustomMainMenu) by changing a line of code in net.minecraft.client.Minecraft#startNewGame() to my own version.

 

From

this.displayGuiScreen(new GuiMainMenu());

To

this.displayGuiScreen(new GuiCustomMainMenu());

 

It works fine when I run my coremod in eclipse but there's bunch of errors when running from the game. From the log, it seems that Forge cannot find "Minecraft.class", which are obfuscated to "atv" in 1.6.4. It also says that no class "avc" which actually exist in the game jar file (as of 1.6.4). My error log and transformer class are shown below. Any help is welcome.

Thanks in advance.

 

EDIT: forgot to mention that one of the exception is caused by the line:

ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);

 

Error log

 

2014-02-21 22:36:59 [FINE] [ForgeModLoader] Running coremod plugin for FMLForgePlugin {net.minecraftforge.classloading.FMLForgePlugin}

2014-02-21 22:36:59 [FINE] [ForgeModLoader] Running coremod plugin FMLForgePlugin

2014-02-21 22:36:59 [FINE] [ForgeModLoader] Coremod plugin class FMLForgePlugin run successfully

2014-02-21 22:36:59 [iNFO] [ForgeModLoader] Calling tweak class cpw.mods.fml.relauncher.CoreModManager$FMLPluginWrapper

2014-02-21 22:36:59 [FINE] [ForgeModLoader] Injecting coremod FPCorePlugin {_fdb.fdbported_core_client.FPCorePlugin} class transformers

2014-02-21 22:36:59 [FINEST] [ForgeModLoader] Registering transformer _fdb.fdbported_core_client.FPTransformer

2014-02-21 22:36:59 [FINE] [ForgeModLoader] Injection complete

2014-02-21 22:36:59 [FINE] [ForgeModLoader] Running coremod plugin for FPCorePlugin {_fdb.fdbported_core_client.FPCorePlugin}

2014-02-21 22:36:59 [FINE] [ForgeModLoader] Running coremod plugin FPCorePlugin

2014-02-21 22:36:59 [FINE] [ForgeModLoader] Coremod plugin class FPCorePlugin run successfully

2014-02-21 22:36:59 [iNFO] [ForgeModLoader] Calling tweak class cpw.mods.fml.common.launcher.FMLDeobfTweaker

2014-02-21 22:36:59 [FINE] [ForgeModLoader] Validating minecraft

2014-02-21 22:37:00 [FINE] [ForgeModLoader] Minecraft validated, launching...

2014-02-21 22:37:00 [iNFO] [ForgeModLoader] Launching wrapped minecraft {net.minecraft.client.main.Main}

2014-02-21 22:37:00 [iNFO] [sTDOUT] Transforming: atv

2014-02-21 22:37:00 [iNFO] [sTDOUT] _fdb/fdbported/client/gui/GuiCustomMainMenu

2014-02-21 22:37:00 [iNFO] [sTDOUT] Accept : atv

2014-02-21 22:37:00 [iNFO] [sTDOUT] Method O()V found. Patching...

2014-02-21 22:37:00 [FINE] [ForgeModLoader] Runtime patching class net/minecraft/world/IBlockAccess (input size 367), found 1 patch

2014-02-21 22:37:00 [FINE] [ForgeModLoader] Successfully applied runtime patches for net/minecraft/world/IBlockAccess (new size 743)

2014-02-21 22:37:00 [sEVERE] [ForgeModLoader] Unable to launch

java.lang.reflect.InvocationTargetException

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

at java.lang.reflect.Method.invoke(Unknown Source)

at net.minecraft.launchwrapper.Launch.launch(Launch.java:131)

at net.minecraft.launchwrapper.Launch.main(Launch.java:27)

Caused by: java.lang.NoClassDefFoundError: net/minecraft/client/Minecraft

at net.minecraft.client.main.Main.main(SourceFile:37)

... 6 more

Caused by: java.lang.ClassNotFoundException: net.minecraft.client.Minecraft

at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:186)

at java.lang.ClassLoader.loadClass(Unknown Source)

at java.lang.ClassLoader.loadClass(Unknown Source)

... 7 more

Caused by: java.lang.RuntimeException: java.lang.ClassNotFoundException: avc

at org.objectweb.asm.ClassWriter.getCommonSuperClass(Unknown Source)

at org.objectweb.asm.ClassWriter.a(Unknown Source)

at org.objectweb.asm.Frame.a(Unknown Source)

at org.objectweb.asm.Frame.a(Unknown Source)

at org.objectweb.asm.MethodWriter.visitMaxs(Unknown Source)

at org.objectweb.asm.tree.MethodNode.accept(Unknown Source)

at org.objectweb.asm.tree.MethodNode.accept(Unknown Source)

at org.objectweb.asm.tree.ClassNode.accept(Unknown Source)

at _fdb.fdbported_core_client.FPTransformer.patchClassClientMinecraft(FPTransformer.java:126)

at _fdb.fdbported_core_client.FPTransformer.transform(FPTransformer.java:36)

at net.minecraft.launchwrapper.LaunchClassLoader.runTransformers(LaunchClassLoader.java:274)

at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:172)

... 9 more

 

 

Transformer class

 

package _fdb.fdbported_core_client;

 

import java.util.Iterator;

 

import net.minecraft.launchwrapper.IClassTransformer;

 

import org.objectweb.asm.ClassReader;

import org.objectweb.asm.ClassWriter;

import org.objectweb.asm.Label;

import org.objectweb.asm.Opcodes;

import org.objectweb.asm.tree.AbstractInsnNode;

import org.objectweb.asm.tree.ClassNode;

import org.objectweb.asm.tree.InsnNode;

import org.objectweb.asm.tree.JumpInsnNode;

import org.objectweb.asm.tree.LabelNode;

import org.objectweb.asm.tree.LdcInsnNode;

import org.objectweb.asm.tree.MethodInsnNode;

import org.objectweb.asm.tree.MethodNode;

import org.objectweb.asm.tree.TypeInsnNode;

import org.objectweb.asm.tree.VarInsnNode;

 

import cpw.mods.fml.common.FMLCommonHandler;

import cpw.mods.fml.relauncher.Side;

 

import _fdb.fdbported.client.gui.GuiCustomMainMenu;

 

public class FPTransformer implements IClassTransformer {

 

public byte[] transform(String classname, String arg1, byte[] data) {

if(classname.equals(unobfDict[0])){

System.out.println("Transforming: "+unobfDict[0]);

return patchClassClientMinecraft(data, false);

}else if(classname.equals(obfDict[0])){

System.out.println("Transforming: "+obfDict[0]);

return patchClassClientMinecraft(data, true);

}

return data;

}

 

private static final String guicustommenu = GuiCustomMainMenu.class.getName().replace('.', '/');

private static final String[] unobfDict = {

"net.minecraft.client.Minecraft","startGame","()V", //0-2

"displayGuiScreen","(Lnet/minecraft/client/gui/GuiScreen;)V", //3-4

};

private static final String[] obfDict = {

"atv","O","()V","a","(Lawe;)V", //0-4

};

 

public byte[] patchClassClientMinecraft(byte[] bytes, boolean obfuscated) {

String[] dict = obfuscated ? obfDict : unobfDict;

System.out.println(guicustommenu);

ClassNode classNode = new ClassNode();

ClassReader classReader = new ClassReader(bytes);

classReader.accept(classNode, 0);

System.out.println("Accept : "+classNode.name);

 

try{

int lastindex = 0;

Iterator<MethodNode> methods = classNode.methods.iterator();

while(methods.hasNext()){

MethodNode m = methods.next();

if(m.name.equals(dict[1]) && m.desc.equals(dict[2])){

System.out.println("Method "+dict[1]+dict[2]+" found. Patching...");

AbstractInsnNode currentNode = null;

int index = 0;

@SuppressWarnings("unchecked")

Iterator<AbstractInsnNode> iter = m.instructions.iterator();

while(iter.hasNext()){

currentNode = iter.next();

if(currentNode.getOpcode() == Opcodes.INVOKEVIRTUAL){

if(currentNode.getType() == AbstractInsnNode.METHOD_INSN){

MethodInsnNode testMethod = (MethodInsnNode)currentNode;

if(testMethod.name.equals(dict[3]) && testMethod.desc.equals(dict[4])){

lastindex = index;

}

}

}

index++;

}

 

TypeInsnNode typeIns = (TypeInsnNode)m.instructions.get(lastindex-3);

MethodInsnNode methodIns = (MethodInsnNode)m.instructions.get(lastindex-1);

typeIns.desc = guicustommenu;

methodIns.owner = guicustommenu;

 

break;

}

}

}catch(Exception e){

//Transformation fail!

return bytes;

}

 

 

ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);

classNode.accept(writer);

return writer.toByteArray();

}

}

 

 

The reason why it says the class "avc" or "Minecraft" doesn't exist is simple. It's the fact that something went wrong during the transformation of the class, so the class is improperly loaded. It would help a lot if you managed to get a print of the exception that is caught during the transformation.

 

However, I advise you to not completely replace GuiMainMenu. I'm very sure Forge modifies this part of minecraft, either by doing what you are doing, or it's patching the vanilla class. You should also patch the vanilla class to avoid conflicts. If it turns out to be a forge class, patch that one instead.

Okay, I've tried printing out stack trace in case that transformation fails and got no more info. I also forgot to mention that one of the exception is caused by the line:

ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);

So it should be that no error occurs during transformation.

 

Also, I didn't replace any class. If you read my code, what I've done is method patching (actually just change 1 line of code).

 

Anyway, thanks for your reply

You could also use the RenderGameOverlayEvent and then check if it is the GuiMainMenu class and then cancel the rendering and then render your own menu

That's an interesting workaround. I'll give it a try! However, I still need some explanations of the error since I'll be using more of method patching to edit some classes.