src/main/java/ftbsc/bscv/patches/BlockPushPatch.java


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package ftbsc.bscv.patches;

import ftbsc.lll.processor.annotations.Find;
import ftbsc.lll.processor.annotations.Injector;
import ftbsc.lll.processor.annotations.Patch;
import ftbsc.lll.processor.annotations.Target;
import ftbsc.lll.proxies.MethodProxy;
import ftbsc.lll.tools.InsnSequence;
import ftbsc.lll.tools.nodes.MethodProxyInsnNode;
import net.minecraft.client.entity.player.ClientPlayerEntity;
import net.minecraftforge.common.MinecraftForge;
import net.minecraftforge.eventbus.api.Cancelable;
import net.minecraftforge.eventbus.api.Event;

import org.objectweb.asm.Opcodes;
import org.objectweb.asm.tree.*;

public class BlockPushPatch {

   @Cancelable
   public static class PlayerBlockPushEvent extends Event {}

   public static boolean shouldCancelBlockCollisions() {
      return MinecraftForge.EVENT_BUS.post(new PlayerBlockPushEvent());
   }

   @Patch(value = ClientPlayerEntity.class, reason = "add hook to cancel block collisions")
   public abstract static class BlockCollisionsOverride implements Opcodes {
      @Find(parent = BlockPushPatch.class)
      abstract MethodProxy shouldCancelBlockCollisions();

      @Target
      abstract void moveTowardsClosestSpace(double x, double z);

      @Injector
      public void inject(ClassNode clazz, MethodNode main) {
         LabelNode skip = new LabelNode();
         InsnSequence is = new InsnSequence();
         is.add(new MethodProxyInsnNode(INVOKESTATIC, shouldCancelBlockCollisions()));
         is.add(new JumpInsnNode(IFEQ, skip));
         is.add(new InsnNode(RETURN));
         is.add(skip);

         main.instructions.insert(is); // hook at top
      }
   }
}