TL;DR

A plugin system which adds Jars to the classloader can call several Minecraft methods when running from within IntelliJ Idea, however it errors when running it in standard Forge (when the mod jar is dropped in the mods folder)

 

Hi there!

I'm trying to develop a plugin system for my mod, however I'm very confused as to why it works when I run / debug it from IntelliJ Idea, but it doesn't work when I put the mod jar in my mods folder, and the plugin in the mods/CraftedCart/MFFClientPlugins folder.

 

The plugin loads, however it errors whenever I try to use several Minecraft methods.

GLStateManager

seems to be broken. It couldn't

pushMatrix

or

translate

BlockPos

also seems to be broken. It errors when I try to

getX()

 

Here's the error for the

getX()

method (

testMFFPlugin

is the plugin, and it's trying to draw a

TESR

).

Caused by: java.lang.NoSuchMethodError: net.minecraft.util.BlockPos.getX()I

The whole stack:

10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: java.lang.reflect.InvocationTargetException
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at sun.reflect.GeneratedMethodAccessor8.invoke(Unknown Source)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at java.lang.reflect.Method.invoke(Method.java:497)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at io.github.craftedcart.MFF.client.render.blocks.TERendererFFProjector.func_180535_a(TERendererFFProjector.java:37)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.client.renderer.tileentity.TileEntityRendererDispatcher.func_178469_a(SourceFile:114)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.client.renderer.tileentity.TileEntityRendererDispatcher.func_180546_a(SourceFile:102)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.client.renderer.RenderGlobal.func_180446_a(RenderGlobal.java:655)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.client.renderer.EntityRenderer.func_175068_a(EntityRenderer.java:1294)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.client.renderer.EntityRenderer.func_78471_a(EntityRenderer.java:1207)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.client.renderer.EntityRenderer.func_78480_b(EntityRenderer.java:1032)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1048)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:345)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.client.main.Main.main(SourceFile:120)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at java.lang.reflect.Method.invoke(Method.java:497)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: Caused by: java.lang.NoSuchMethodError: net.minecraft.util.BlockPos.getX()I
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	at io.github.craftedcart.TestMFFPlugin.TestMFFPluginBase.renderTEFFProjector(TestMFFPluginBase.java:65)
[10:19:29] [Client thread/INFO] [sTDERR]: [java.lang.Throwable$WrappedPrintStream:println:748]: 	... 19 more
FramebufferStatus 0x0000 at beginHand
FramebufferStatus 0x0000 at pre endHand
GL error 0x0502: Invalid operation at renderCompositeFinal

 

The details of how plugins are loaded:

 

1: Plugins are added to the class loader

LaunchClassLoader loader = (LaunchClassLoader) DependencyUtils.class.getClassLoader(); //DependencyUtils is one of my classes
loader.addURL(file.toURI().toURL()); //In this case, the file variable would be the mods/CraftedCart/MFFClientPlugins/testMFFPlugin.jar file

 

2: Plugins are searched for an

@MFFClientPlugin

annotation using Reflections (Note the extra s on the end of that. It's an external library)

Reflections reflections = new Reflections();
clientPlugins = reflections.getTypesAnnotatedWith(MFFClientPlugin.class);

 

3: The

load()

method is called on all plugins using Reflection

for (Class clazz : clientPlugins) {
    Method loadMethod = clazz.getMethod("load");
    loadMethod.invoke(clazz.newInstance());
}

 

In the test plugin, it would set 2 variables (The method to call when rendering the TESR, and its class)

The TESR then uses Reflection to invoke the method on that class

If you want to run code in actual Minecraft, not in dev, you need to reobfuscate your code. ForgeGradle does this automatically for you when you run

gradle build

.

 

You also need to keep this in mind if you use reflection with Minecraft's classes.

 

Every field/method has an SRG (semi-obfuscated) name like

field_00120_a

/

func_12345_b

and most fields/methods also have an MCP (deobfuscated) name like

thing

/

getThing

. You need to make sure you check both names when using reflection. FML's

ReflectionHelper

and

ObfuscationReflectionHelper

have methods to find a field/method with one of several names via reflection.

 

You can find the SRG name of a field/method in the MCP mapping CSVs. If you've set up a ForgeGradle workspace for 1.8+, you can find the mappings it's using in the Gradle cache (~/.gradle/caches/minecraft/de/oceanlabs/mcp/<mappings_channel>/<mappings_version>, replace ~ with %USERPROFILE% on Windows). You can also download them from the MCPBot website.

 

External libraries and Forge/FML code (including new methods/fields in vanilla classes) aren't affected by this, everything just has the one name.

If you want to run code in actual Minecraft, not in dev, you need to reobfuscate your code. ForgeGradle does this automatically for you when you run

gradle build

.

 

Ah, I probably should have said that I packaged the code into a .jar (IntelliJ's Build > Build Artifact) when it was running in the dev environment, and that the dev environment read from that jar, rather than reading from the soruce.