Added hook that inserts "Hello World" print into Minecraft#startGame

exejar · exejar · commit 31fd9a076dd1 · 2023-02-25T23:05:27.000-05:00
diff --git a/src/main/kotlin/com/example/mod/Entry.kt b/src/main/kotlin/com/example/mod/Entry.kt
@@ -2,9 +2,11 @@ package com.example.mod
 
 import club.maxstats.weave.api.ModInitializer
 import club.maxstats.weave.api.hook.HookManager
+import com.example.mod.hooks.MinecraftHook
 
 class Entry: ModInitializer {
     override fun init(hookManager: HookManager){
+        hookManager.add(MinecraftHook())
         println("Example Mod Initialized")
     }
 }
diff --git a/src/main/kotlin/com/example/mod/hooks/MinecraftHook.kt b/src/main/kotlin/com/example/mod/hooks/MinecraftHook.kt
@@ -0,0 +1,28 @@
+package com.example.mod.hooks
+
+import club.maxstats.weave.api.hook.Hook
+import org.objectweb.asm.Opcodes
+import org.objectweb.asm.tree.ClassNode
+import org.objectweb.asm.tree.FieldInsnNode
+import org.objectweb.asm.tree.InsnList
+import org.objectweb.asm.tree.LdcInsnNode
+import org.objectweb.asm.tree.MethodInsnNode
+import org.objectweb.asm.tree.MethodNode
+
+class MinecraftHook: Hook("net.minecraft.client.Minecraft") {
+    override fun transform(cn: ClassNode) {
+        for (method: MethodNode in cn.methods) {
+            if (method.name.equals("startGame")) {
+                this.startGameInject(method)
+            }
+        }
+    }
+
+    private fun startGameInject(method: MethodNode) {
+        val inject = InsnList()
+        inject.add(FieldInsnNode(Opcodes.GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;"))
+        inject.add(LdcInsnNode("Hello World from Minecraft#startGame"))
+        inject.add(MethodInsnNode(Opcodes.INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V"))
+        method.instructions.insert(inject)
+    }
+}

Original file line number	Diff line number	Diff line change
`@@ -2,9 +2,11 @@ package com.example.mod`
`2`	`2`
`3`	`3`	`import club.maxstats.weave.api.ModInitializer`
`4`	`4`	`import club.maxstats.weave.api.hook.HookManager`
	`5`	`+import com.example.mod.hooks.MinecraftHook`
`5`	`6`
`6`	`7`	`class Entry: ModInitializer {`
`7`	`8`	`override fun init(hookManager: HookManager){`
	`9`	`+ hookManager.add(MinecraftHook())`
`8`	`10`	`println("Example Mod Initialized")`
`9`	`11`	`}`
`10`	`12`	`}`