From 715dda9d24630aa389aace7fd872cd22191e0760 Mon Sep 17 00:00:00 2001
From: Moresteck <moresteck@protonmail.com>
Date: Tue, 15 Oct 2024 11:18:48 +0000
Subject: [PATCH] Impl: OpenGlHelper patch for Intel Graphics driver

---
 .../betacraft/legacyfix/LegacyFixAgent.java   |  1 +
 .../legacyfix/patch/impl/IntelPatch.java      | 83 +++++++++++++++++++
 2 files changed, 84 insertions(+)
 create mode 100644 src/main/java/uk/betacraft/legacyfix/patch/impl/IntelPatch.java

diff --git a/src/main/java/uk/betacraft/legacyfix/LegacyFixAgent.java b/src/main/java/uk/betacraft/legacyfix/LegacyFixAgent.java
index 8b6eb7b..241474c 100644
--- a/src/main/java/uk/betacraft/legacyfix/LegacyFixAgent.java
+++ b/src/main/java/uk/betacraft/legacyfix/LegacyFixAgent.java
@@ -45,6 +45,7 @@ public static void premain(String agentArgs, final Instrumentation inst) {
                 new BitDepthPatch(),
                 new ClassicPatch(),
                 new GameDirPatch(),
+                new IntelPatch(),
                 new DeAwtPatch(),
                 new MousePatch(),
                 new VSyncPatch()
diff --git a/src/main/java/uk/betacraft/legacyfix/patch/impl/IntelPatch.java b/src/main/java/uk/betacraft/legacyfix/patch/impl/IntelPatch.java
new file mode 100644
index 0000000..5aeaf52
--- /dev/null
+++ b/src/main/java/uk/betacraft/legacyfix/patch/impl/IntelPatch.java
@@ -0,0 +1,83 @@
+package uk.betacraft.legacyfix.patch.impl;
+
+import javassist.CannotCompileException;
+import javassist.CtClass;
+import javassist.CtMethod;
+import javassist.expr.ExprEditor;
+import javassist.expr.MethodCall;
+import uk.betacraft.legacyfix.LFLogger;
+import uk.betacraft.legacyfix.LegacyFixAgent;
+import uk.betacraft.legacyfix.patch.Patch;
+import uk.betacraft.legacyfix.patch.PatchException;
+
+import java.lang.instrument.ClassFileTransformer;
+import java.lang.instrument.Instrumentation;
+import java.lang.reflect.Modifier;
+import java.security.ProtectionDomain;
+
+/**
+ * Patches OpenGlHelper to fix rendering on Intel graphics (when using performance trick JVM argument)
+ * <a href="https://www.minecraftforum.net/forums/mapping-and-modding-java-edition/minecraft-mods/1294926-themastercavers-world?page=13#c294">Reference</a>
+ */
+public class IntelPatch extends Patch {
+    public IntelPatch() {
+        super("intelpatch", "Patches rendering on Intel", false);
+    }
+
+    public void apply(final Instrumentation inst) throws PatchException, Exception {
+        inst.addTransformer(new ClassFileTransformer() {
+            public byte[] transform(ClassLoader loader, String className, Class<?> classRedefined, ProtectionDomain domain, byte[] classfileBuffer) {
+                CtClass clas = pool.getOrNull(className.replace("/", "."));
+                if (clas == null || clas.getName().startsWith("org.lwjgl") || clas.getDeclaredConstructors().length != 1 || clas.isFrozen()) {
+                    return null;
+                }
+
+                try {
+                    final boolean[] openGlHelperMatched = new boolean[1];
+                    for (CtMethod glActiveTextureMethod : clas.getDeclaredMethods()) {
+                        if (!Modifier.isPublic(glActiveTextureMethod.getModifiers()) ||
+                                !Modifier.isStatic(glActiveTextureMethod.getModifiers()) ||
+                                !"void".equals(glActiveTextureMethod.getReturnType().getName()) ||
+                                glActiveTextureMethod.getParameterTypes().length != 1 ||
+                                !"int".equals(glActiveTextureMethod.getParameterTypes()[0].getName())) {
+                            continue;
+                        }
+
+                        glActiveTextureMethod.instrument(new ExprEditor() {
+                            public void edit(MethodCall m) throws CannotCompileException {
+                                if ("org.lwjgl.opengl.ARBMultitexture".equals(m.getClassName()) &&
+                                        "glActiveTextureARB".equals(m.getMethodName()) &&
+                                        "(I)V".equalsIgnoreCase(m.getSignature())) {
+                                    openGlHelperMatched[0] = true;
+                                    m.replace("{ org.lwjgl.opengl.ARBMultitexture.glClientActiveTextureARB($$); $_ = $proceed($$); }");
+                                    if (LegacyFixAgent.isDebug())
+                                        LFLogger.info("intelpatch", "Matched ARBMultitexture.glActiveTextureARB(I)V");
+
+                                } else if ("org.lwjgl.opengl.GL13".equals(m.getClassName()) &&
+                                        "glActiveTexture".equals(m.getMethodName()) &&
+                                        "(I)V".equalsIgnoreCase(m.getSignature())) {
+                                    openGlHelperMatched[0] = true;
+                                    m.replace("{ org.lwjgl.opengl.GL13.glClientActiveTexture($$); $_ = $proceed($$); }");
+                                    if (LegacyFixAgent.isDebug())
+                                        LFLogger.info("intelpatch", "Matched GL13.glActiveTexture(I)V");
+                                }
+                            }
+                        });
+
+                        if (openGlHelperMatched[0]) {
+                            if (LegacyFixAgent.isDebug())
+                                LFLogger.info("intelpatch", "Found OpenGlHelper and patched it: " + clas.getName());
+
+                            inst.removeTransformer(this); // job is done, don't transform any more classes
+                            return clas.toBytecode();
+                        }
+                    }
+                } catch (Throwable t) {
+                    LFLogger.error("intelpatch", t);
+                }
+
+                return null;
+            }
+        });
+    }
+}