Remove annoying GL error message from Optifine/Shadersmod (#279)

src/main/java/com/mitchej123/hodgepodge/LoadingConfig.java

@@ -123,6 +123,7 @@ public class LoadingConfig {
     public boolean preventPickupLoot;
     public boolean removeSpawningMinecartSound;
     public boolean removeCreativeSearchTab;
+    public boolean removeOptifineGLErrors;
 
     public boolean compactChat;
     public boolean dontInvertCrosshairColor;
@@ -326,6 +327,7 @@ public LoadingConfig(File file) {
         enableMacosCmdShortcuts = config.get(Category.TWEAKS.toString(), "enableMacosCmdShortcuts", true, "Use CMD key on MacOS to COPY / INSERT / SELECT in text fields (Chat, NEI, Server IP etc.)").getBoolean();
         removeSpawningMinecartSound = config.get(Category.TWEAKS.toString(), "removeSpawningMinecartSound", true, "Stop playing a sound when spawning a minecart in the world").getBoolean();
         removeCreativeSearchTab = config.get(Category.FIXES.toString(), "removeCreativeSearchTab", true, "Disable the creative search tab since it can be very laggy in large modpacks").getBoolean();
+        removeOptifineGLErrors = config.get(Category.TWEAKS.toString(), "removeOptifineGLErrors", true, "Removes the 'GL error' message that appears when using a shader in Optifine/Shadersmod").getBoolean();
         removeUpdateChecks = config.get(Category.FIXES.toString(), "removeUpdateChecks", true, "Remove old/stale/outdated update checks.").getBoolean();
         chunkSaveCMEDebug = config.get(Category.DEBUG.toString(), "chunkSaveCMEDebug", false, "Enable chunk save cme debugging code.").getBoolean();
         renderDebug = config.get(Category.DEBUG.toString(), "renderDebug", true, "Enable GL state debug hooks. Will not do anything useful unless mode is changed to nonzero.").getBoolean();

src/main/java/com/mitchej123/hodgepodge/asm/AsmTransformers.java

@@ -21,7 +21,12 @@ public enum AsmTransformers {
             "Take a sledgehammer to CraftServer.resetRecipes() to prevent it from breaking our Furnace Fix",
             () -> Common.thermosTainted && Common.config.speedupVanillaFurnace,
             Side.BOTH,
-            "com.mitchej123.hodgepodge.asm.transformers.thermos.ThermosFurnaceSledgeHammer");
+            "com.mitchej123.hodgepodge.asm.transformers.thermos.ThermosFurnaceSledgeHammer"),
+    OPTIFINE_REMOVE_GLERROR_LOGGING(
+            "Removes the logging of GL errors from OptiFine/Shadersmod",
+            () -> Common.config.removeOptifineGLErrors,
+            Side.CLIENT,
+            "com.mitchej123.hodgepodge.asm.transformers.optifine.GLErrorLoggingTransformer");
     // spotless:on
 
     private final Supplier<Boolean> applyIf;

src/main/java/com/mitchej123/hodgepodge/asm/transformers/optifine/GLErrorLoggingTransformer.java

@@ -0,0 +1,75 @@
+package com.mitchej123.hodgepodge.asm.transformers.optifine;
+
+import java.util.Iterator;
+
+import net.minecraft.launchwrapper.IClassTransformer;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.objectweb.asm.ClassReader;
+import org.objectweb.asm.ClassWriter;
+import org.objectweb.asm.Opcodes;
+import org.objectweb.asm.tree.ClassNode;
+import org.objectweb.asm.tree.InsnList;
+import org.objectweb.asm.tree.InsnNode;
+import org.objectweb.asm.tree.LabelNode;
+import org.objectweb.asm.tree.LocalVariableNode;
+import org.objectweb.asm.tree.MethodInsnNode;
+import org.objectweb.asm.tree.MethodNode;
+
+public class GLErrorLoggingTransformer implements IClassTransformer, Opcodes {
+
+    @Override
+    public byte[] transform(String name, String transformedName, byte[] basicClass) {
+        if ("shadersmod.client.Shaders".equals(transformedName)) {
+            final Logger logger = LogManager.getLogger("GLErrorLogging");
+            logger.debug("TRANSFORMING shadersmod.client.Shaders");
+            final ClassReader cr = new ClassReader(basicClass);
+            final ClassNode cn = new ClassNode();
+            cr.accept(cn, 0);
+            label: for (MethodNode mn : cn.methods) {
+                if (mn.name.equals("checkGLError")) {
+                    final int maxlocals;
+                    switch (mn.desc) {
+                        case "(Ljava/lang/String;)I":
+                            maxlocals = 1;
+                            break;
+                        case "(Ljava/lang/String;Ljava/lang/String;)I":
+                            maxlocals = 2;
+                            break;
+                        case "(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)I":
+                            maxlocals = 3;
+                            break;
+                        default:
+                            break label;
+                    }
+                    logger.debug("Removing GL Error Logging: " + mn.desc);
+                    mn.visitMaxs(1, maxlocals);
+                    final InsnList list = mn.instructions;
+                    list.clear();
+                    LabelNode l0 = new LabelNode();
+                    LabelNode l1 = new LabelNode();
+                    list.add(l0);
+                    list.add(new MethodInsnNode(INVOKESTATIC, "org/lwjgl/opengl/GL11", "glGetError", "()I", false));
+                    list.add(new InsnNode(IRETURN));
+                    list.add(l1);
+                    final Iterator<LocalVariableNode> it = mn.localVariables.iterator();
+                    while (it.hasNext()) {
+                        final LocalVariableNode lv = it.next();
+                        if (lv.desc.equals("Ljava/lang/String;")) {
+                            lv.start = l0;
+                            lv.end = l1;
+                        } else {
+                            it.remove();
+                        }
+                    }
+                }
+            }
+            final ClassWriter cw = new ClassWriter(0);
+            cn.accept(cw);
+            return cw.toByteArray();
+        }
+
+        return basicClass;
+    }
+}