(Solved) [1.16.4] Loot Modification, get the basics to work

[FenrisFox86]

I'm working on a Mod that introduces quite a couple of new tools to the game and right now I'm working on a Hammer that's pretty similar to the one from Ex Nihilo if this is still a thing. It can destroy the same blocks as a Pickaxe but as soon as it causes a loot drop, it will replace certain Items. Cobblestone will turn into gravel for example. 

So first I need to understand the basics about Loot Modification. I read the docs and to get an understanding of how it works, I first just copied the code out of the forge docs and tested it. Of course it didn't work.

My problem right now is that I don't have clue where the error lies since there are no errors thrown by the game. It just doesn't replace the drops. So below you'll find the relevant code snippets and where in the mod files they're located.

for simplicity's sake I removed any too specific code and made the CrusherModifier#doApply method simply add a diamond to any drop that's caused by shears when it finally works.

Anyone got a clue what I could've done wrong? maybe the json files' locations?

 

global_loot_modifiers.json at data/forge/loot_modifiers/global_loot_modifiers.json:

{
  "replace": false,
  "entries": [
    "fenriscore:crush_drop"
  ]
}

 

crush.json at data/fenriscore/loot_modifiers/crush_drop.json

{
  "type": "fenriscore:crush_drop",
  "conditions": [
    {
      "condition": "minecraft:match_tool",
      "predicate": {
        "item": "minecraft:shears"
      }
    }
  ]
}

 

The CrusherModifier class:

package com.FenrisFox86.fenriscore.core.util.tools;

import com.google.gson.JsonObject;
import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;
import net.minecraft.item.Items;
import net.minecraft.loot.LootContext;
import net.minecraft.loot.conditions.ILootCondition;
import net.minecraft.util.JSONUtils;
import net.minecraft.util.ResourceLocation;
import net.minecraftforge.common.loot.GlobalLootModifierSerializer;
import net.minecraftforge.common.loot.LootModifier;
import net.minecraftforge.registries.ForgeRegistries;

import javax.annotation.Nonnull;
import java.util.List;

public class CrusherModifier extends LootModifier {

    public CrusherModifier(ILootCondition[] conditionsIn) {
        super(conditionsIn);
    }

    @Nonnull
    @Override
    public List<ItemStack> doApply(List<ItemStack> generatedLoot, LootContext context) {
        generatedLoot.add(new ItemStack(Items.DIAMOND, 1));
        return generatedLoot;
    }

    public static class Serializer extends GlobalLootModifierSerializer<CrusherModifier> {

        @Override
        public CrusherModifier read(ResourceLocation name, JsonObject object, ILootCondition[] conditionsIn) {
            return new CrusherModifier(conditionsIn);
        }

        @Override
        public JsonObject write(CrusherModifier instance) {
            JsonObject json = makeConditions(instance.conditions);
            return json;
        }
    }
}

 

The part of the main mod class where I register the CrusherModifier:

@SubscribeEvent
    public static void registerModifierSerializers(@Nonnull final RegistryEvent.Register<GlobalLootModifierSerializer<?>> event) {

        event.getRegistry().register(new CrusherModifier.Serializer().setRegistryName(
                new ResourceLocation(MOD_ID,"crush_drop")));
    }

 

Edited July 1, 2021 by FenrisFox86

[FenrisFox86]

Yes, I used shears. 

And no, I don't actively call the serializer. I thought that the serializer is automatically called when a loot drop is performed. 

 

[FenrisFox86]

Oh, I just found a related Error in the log. It couldn't parse the loot modifier. 

Does that mean that it didn't find the file at all or that I did something wrong inside the file? I think it's rather less probable that the file itsself is written the wrong way. I pretty much copied it from the docs. 

 

[16:45:17] [Render thread/ERROR] [ne.mi.co.lo.LootModifierManager/]: Couldn't parse loot modifier fenriscore:crush_drop
java.lang.NullPointerException: null
	at net.minecraftforge.common.loot.LootModifierManager.deserializeModifier(LootModifierManager.java:139) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading}
	at net.minecraftforge.common.loot.LootModifierManager.lambda$apply$0(LootModifierManager.java:115) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading}
	at java.util.ArrayList.forEach(ArrayList.java:1259) ~[?:1.8.0_261] {}
	at net.minecraftforge.common.loot.LootModifierManager.apply(LootModifierManager.java:113) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading}
	at net.minecraftforge.common.loot.LootModifierManager.apply(LootModifierManager.java:54) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading}
	at net.minecraft.client.resources.ReloadListener.lambda$reload$1(ReloadListener.java:14) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading}
	at java.util.concurrent.CompletableFuture.uniAccept(CompletableFuture.java:670) ~[?:1.8.0_261] {}
	at java.util.concurrent.CompletableFuture$UniAccept.tryFire(CompletableFuture.java:646) ~[?:1.8.0_261] {}
	at java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:456) ~[?:1.8.0_261] {}
	at net.minecraft.resources.AsyncReloader.lambda$null$3(AsyncReloader.java:66) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading}
	at net.minecraft.util.concurrent.ThreadTaskExecutor.run(ThreadTaskExecutor.java:139) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.util.concurrent.RecursiveEventLoop.run(RecursiveEventLoop.java:22) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading}
	at net.minecraft.util.concurrent.ThreadTaskExecutor.driveOne(ThreadTaskExecutor.java:109) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.util.concurrent.ThreadTaskExecutor.driveUntil(ThreadTaskExecutor.java:122) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.client.Minecraft.reloadDatapacks(Minecraft.java:1905) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
	at net.minecraft.client.Minecraft.loadWorld(Minecraft.java:1758) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
	at net.minecraft.client.Minecraft.loadWorld(Minecraft.java:1728) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
	at net.minecraft.client.gui.screen.WorldSelectionList$Entry.func_214443_e(WorldSelectionList.java:364) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.client.gui.screen.WorldSelectionList$Entry.func_214438_a(WorldSelectionList.java:273) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.client.gui.screen.WorldSelectionList$Entry.mouseClicked(WorldSelectionList.java:225) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.client.gui.widget.list.AbstractList.mouseClicked(AbstractList.java:309) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.client.gui.INestedGuiEventHandler.mouseClicked(INestedGuiEventHandler.java:31) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.client.MouseHelper.lambda$mouseButtonCallback$0(MouseHelper.java:92) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.client.gui.screen.Screen.wrapScreenError(Screen.java:427) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.client.MouseHelper.mouseButtonCallback(MouseHelper.java:90) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.client.MouseHelper.lambda$null$4(MouseHelper.java:185) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.util.concurrent.ThreadTaskExecutor.execute(ThreadTaskExecutor.java:86) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:accesstransformer:B}
	at net.minecraft.client.MouseHelper.lambda$registerCallbacks$5(MouseHelper.java:184) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
	at org.lwjgl.glfw.GLFWMouseButtonCallbackI.callback(GLFWMouseButtonCallbackI.java:36) ~[lwjgl-glfw-3.2.2.jar:build 10] {}
	at org.lwjgl.system.JNI.invokeV(Native Method) ~[lwjgl-3.2.2.jar:build 10] {}
	at org.lwjgl.glfw.GLFW.glfwPollEvents(GLFW.java:3101) ~[lwjgl-glfw-3.2.2.jar:build 10] {}
	at com.mojang.blaze3d.systems.RenderSystem.flipFrame(RenderSystem.java:93) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.client.MainWindow.flipFrame(MainWindow.java:305) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.client.Minecraft.runGameLoop(Minecraft.java:1022) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
	at net.minecraft.client.Minecraft.run(Minecraft.java:612) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
	at net.minecraft.client.main.Main.main(Main.java:184) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {re:classloading,pl:runtimedistcleaner:A}
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_261] {}
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_261] {}
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_261] {}
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_261] {}
	at net.minecraftforge.userdev.FMLUserdevClientLaunchProvider.lambda$launchService$0(FMLUserdevClientLaunchProvider.java:52) ~[forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {}
	at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37) [modlauncher-8.0.9.jar:?] {}
	at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54) [modlauncher-8.0.9.jar:?] {}
	at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72) [modlauncher-8.0.9.jar:?] {}
	at cpw.mods.modlauncher.Launcher.run(Launcher.java:82) [modlauncher-8.0.9.jar:?] {}
	at cpw.mods.modlauncher.Launcher.main(Launcher.java:66) [modlauncher-8.0.9.jar:?] {}
	at net.minecraftforge.userdev.LaunchTesting.main(LaunchTesting.java:105) [forge-1.16.4-35.1.37_mapped_snapshot_20201028-1.16.3-recomp.jar:?] {}

 

[FenrisFox86]

So this code snipped here is probably wrong. But how do I register the Serializer if not like this?

@SubscribeEvent
    public static void registerModifierSerializers(@Nonnull final RegistryEvent.Register<GlobalLootModifierSerializer<?>> event) {

        event.getRegistry().register(new CrusherModifier.Serializer().setRegistryName(
                new ResourceLocation(MOD_ID,"crush_drop")));
    }

 

[Luis_ST]

3 minutes ago, FenrisFox86 said:

So this code snipped here is probably wrong. But how do I register the Serializer if not like this?

looks good show the complete class

 

[FenrisFox86]

Well here you have it. I'm just not too sure if this is helpful since its just the mod's core class. 

package com.FenrisFox86.fenriscore;

import ...

// The value here should match an entry in the META-INF/mods.toml file
@Mod("fenriscore")
public class FenrisCore {
    private static final Logger LOGGER = LogManager.getLogger();

    public static final String MOD_ID = "fenriscore";

    public FenrisCore() {
        // Register the setup and doClientStuff methods for modloading
        FMLJavaModLoadingContext.get().getModEventBus().addListener(this::setup);
        FMLJavaModLoadingContext.get().getModEventBus().addListener(this::doClientStuff);

        ItemInit.ItemInit();
        BlockInit.BlockInit();
        EnchantmentInit.EnchantmentInit();

        // Register for important server and other game events
        MinecraftForge.EVENT_BUS.register(this);
    }

    private void setup(final FMLCommonSetupEvent event)
    {
        CapabilityManager.INSTANCE.register(ICombatState.class, new CombatStageStorage(), DefaultCombatState::new);
        RenderTypeLookup.setRenderLayer(BlockInit.ESSENCE_BLOCK.get(), RenderType.getTranslucent());
    }

    private void doClientStuff(final FMLClientSetupEvent event)
    {

    }

    public static final ItemGroup MOD_TAB = new ItemGroup("basic_material_tab") {
        @Override
        public ItemStack createIcon() {
            return new ItemStack(ItemInit.RUBY.get());
        }
    };

    @SubscribeEvent
    public static void registerModifierSerializers(@Nonnull final RegistryEvent.Register<GlobalLootModifierSerializer<?>> event) {

        event.getRegistry().register(new CrusherModifier.Serializer().setRegistryName(
                new ResourceLocation(MOD_ID,"crush_drop")));
    }
}

 

[FenrisFox86]

So I moved that to a new class that is registered to the event bus. The error stays the same.

package com.FenrisFox86.fenriscore.common.events;

import ...

@Mod.EventBusSubscriber
public class LootModifierEvents {

    @SubscribeEvent
    public void registerModifierSerializers(@Nonnull final RegistryEvent.Register<GlobalLootModifierSerializer<?>> event) {

        event.getRegistry().register(new CrusherModifier.Serializer().setRegistryName(
                new ResourceLocation(FenrisCore.MOD_ID,"crush_drop")));
    }
}

 

[FenrisFox86]

Solved:

Thank you for your patient help. It works now and believe me, the satisfaction of having a diamond pop out of a grass block after hours of making stupid mistakes is way greater than the satisfaction of just finding a Diamond in survival .

This is the final class for registry: 

package com.FenrisFox86.fenriscore.common.events;

import ...

@Mod.EventBusSubscriber(modid = FenrisCore.MOD_ID, bus = Mod.EventBusSubscriber.Bus.MOD)
public class LootModifierEvents {

    @SubscribeEvent
    public static void registerModifierSerializers(@Nonnull final RegistryEvent.Register<GlobalLootModifierSerializer<?>> event) {
        System.out.println("registered");
        event.getRegistry().register(new CrusherModifier.Serializer().setRegistryName(
                new ResourceLocation(FenrisCore.MOD_ID,"crush_drop")));
    }
}