[1.10.2] Understanding Capabilities

Beetle90 · December 23, 2016

Hey guys! I've been trying to understand how Capabilities work. I want to create a simple mod that displays a player's coordinates when given a command, and a player's death coordinates when given that same command with one argument. So far I've gotten the first part down perfectly. The second part has been difficult because I want to store the death coordinates into a capability and then retrieve it when the command is used.

The code in it's current state crashes completely. I've been following this tutorial as a guideline: http://www.planetminecraft.com/blog/forge-tutorial-capability-system/ Hopefully someone here can help figure out what's wrong with my code. I'd love to be able to understand what's going wrong. Capabilities seem extremely useful and I'd love to be able to learn how to use them.

I know there's a lot to share below, but I can't pinpoint at what location my capability setup is incorrect. I appreciate any and all criticism that will help me improve! Here's my code:

main

package blazebeetle.mod;

import blazebeetle.capabilities.Ideathloc;
import blazebeetle.capabilities.deathHandler;
import blazebeetle.capabilities.deathProvider;
import blazebeetle.commands.coords;
import net.minecraft.command.ServerCommandManager;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.util.ResourceLocation;
import net.minecraftforge.common.MinecraftForge;
import net.minecraftforge.event.AttachCapabilitiesEvent;
import net.minecraftforge.event.entity.living.LivingDeathEvent;
import net.minecraftforge.event.entity.player.PlayerEvent;
import net.minecraftforge.fml.common.Mod;
import net.minecraftforge.fml.common.Mod.EventHandler;
import net.minecraftforge.fml.common.event.FMLServerStartingEvent;
import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
import net.minecraftforge.fml.common.gameevent.PlayerEvent.PlayerLoggedInEvent;
import net.minecraftforge.fml.common.network.NetworkRegistry;

@Mod(modid = BlazeBeetle.MODID, version = BlazeBeetle.VERSION)
public class BlazeBeetle
{
    public static final String MODID = "blazebeetle";
    public static final String VERSION = "0.0.0";
    
    
    @EventHandler
    public void serverStart(FMLServerStartingEvent event){
    	ServerCommandManager manager = (ServerCommandManager) event.getServer().getCommandManager();
    	manager.registerCommand(new coords());
    	MinecraftForge.EVENT_BUS.register(new deathHandler());
    }
    
    @SubscribeEvent
    public void onPlayerLogsIn(PlayerLoggedInEvent event){
    	System.out.println("Logged in!!!!!!");
    	EntityPlayer player = event.player;
    	Ideathloc deathloc = player.getCapability(deathProvider.DEATHLOC_CAP, null);
    }
    
   /* @SubscribeEvent
    public void onPlayerDeath(LivingDeathEvent event){
    	System.out.println("I DIED");
    	if (event.getEntity() instanceof EntityPlayer){
    		EntityPlayer player = (EntityPlayer)event.getEntityLiving();
    		Ideathloc deathloc = player.getCapability(deathProvider.DEATHLOC_CAP, null);
    		deathloc.setLoc(player.getPositionVector().xCoord, player.getPositionVector().yCoord, player.getPositionVector().zCoord);
    		System.out.println("set new death loc");
    	}
    }*/
}

coords command class

package blazebeetle.commands;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.ListIterator;

import blazebeetle.capabilities.Ideathloc;
import blazebeetle.capabilities.deathProvider;
import jline.internal.Nullable;
import net.minecraft.command.CommandBase;
import net.minecraft.command.CommandException;
import net.minecraft.command.ICommandSender;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.server.MinecraftServer;
import net.minecraft.util.math.BlockPos;
import net.minecraft.util.text.TextComponentString;
import net.minecraft.util.text.TextFormatting;

public class coords extends CommandBase{

@Override
public String getCommandName() {
	return "coords";
}

@Override
public String getCommandUsage(ICommandSender sender) {
	return "Displays the player's location to everyone.";
}

@Override
    public int getRequiredPermissionLevel()
    {
        return 0;
    }

@Override
public void execute(MinecraftServer server, ICommandSender sender, String[] args) throws CommandException {
	if (sender instanceof EntityPlayer){
		EntityPlayer player = (EntityPlayer)sender;
		int dim_id = player.dimension;
		String dim_string = null;
		switch (dim_id){
		case -1: dim_string = "The Nether";
		break;
		case 0: dim_string = "The Overworld";
		break;
		case 1: dim_string = "The End";
		break;
		default: dim_string = "Dimension " + dim_id;
		}
		TextComponentString text = new TextComponentString(TextFormatting.YELLOW + "<" + player.getDisplayNameString() + "> I'm at x=" + (int)(player.getPositionVector().xCoord) + " z=" + (int)(player.getPositionVector().zCoord) + " y=" + (int)(player.getPositionVector().yCoord) + " in " + dim_string);
		if (args.length == 0){
			player.addChatComponentMessage(text);
		}
		else if (args.length == 1){
			System.out.println("inside length 1");
			if (args[0].equalsIgnoreCase("death")){
				System.out.println("inside death");
				Ideathloc deathloc = player.getCapability(deathProvider.DEATHLOC_CAP,null);
				player.addChatComponentMessage(new TextComponentString(TextFormatting.YELLOW + "I HAVENT CODED THIS YET!!!"));
				player.addChatComponentMessage(new TextComponentString(TextFormatting.YELLOW + "<" + player.getDisplayNameString() + "> I died at x=" + (int)deathloc.getLoc().xCoord + " z=" + (int)deathloc.getLoc().zCoord + " y=" + (int)deathloc.getLoc().yCoord + " in SOME FUCKING DIMENSION!!!"));
				return;
			}

			String[] playerList = server.getAllUsernames();
			for (int i = 0; i < playerList.length; i++){
				if (args[0].equalsIgnoreCase(playerList[i])){
					EntityPlayer receiver = server.getEntityWorld().getPlayerEntityByName(playerList[i]);
					receiver.addChatMessage(text);
				}
			}
		}
	}
}

@Override
    public List<String> getTabCompletionOptions(MinecraftServer server, ICommandSender sender, String[] args, @Nullable BlockPos pos)
    {	
        return args.length == 0 ? Collections.<String>emptyList() : getListOfStringsMatchingLastWord(args, server.getAllUsernames());
    }

}

Ideathloc

package blazebeetle.capabilities;

import net.minecraft.nbt.NBTTagCompound;
import net.minecraft.util.math.Vec3d;

public interface Ideathloc {
public void writeLoc();
public NBTTagCompound getLocComp();
public Vec3d getLoc();
public void setLoc();
public void setLoc(double x, double y, double z);
}

deathloc

package blazebeetle.capabilities;

import net.minecraft.nbt.NBTTagCompound;
import net.minecraft.util.math.Vec3d;

public class deathloc implements Ideathloc{

private Vec3d location;
private NBTTagCompound nbt;
double x;
double y;
double z;

public void writeLoc(){
	nbt.setDouble("x", this.x);
	nbt.setDouble("y", this.y);
	nbt.setDouble("z", this.z);
}

public NBTTagCompound getLocComp() {
	return nbt;
}

public void setLoc() {
	Vec3d temp = new Vec3d(nbt.getDouble("x"), nbt.getDouble("y"), nbt.getDouble("z"));
}

@Override
public void setLoc(double x, double y, double z) {
	location = new Vec3d(x, y, z);
	this.x = x;
	this.y = y;
	this.z = z;

}

@Override
public Vec3d getLoc() {
	return location;
}

}

deathStorage

package blazebeetle.capabilities;

import net.minecraft.nbt.NBTBase;
import net.minecraft.nbt.NBTTagCompound;
import net.minecraft.util.EnumFacing;
import net.minecraftforge.common.capabilities.Capability;
import net.minecraftforge.common.capabilities.Capability.IStorage;

public class deathStorage implements IStorage<Ideathloc>{

@Override
public NBTBase writeNBT(Capability<Ideathloc> capability, Ideathloc instance, EnumFacing side) {
	instance.writeLoc();
	return (instance.getLocComp());
}

@Override
public void readNBT(Capability<Ideathloc> capability, Ideathloc instance, EnumFacing side, NBTBase nbt) {
	instance.setLoc();

}
}

deathProvider

package blazebeetle.capabilities;

import net.minecraft.nbt.NBTBase;
import net.minecraft.util.EnumFacing;
import net.minecraftforge.common.capabilities.Capability;
import net.minecraftforge.common.capabilities.CapabilityInject;
import net.minecraftforge.common.capabilities.ICapabilitySerializable;

public class deathProvider implements ICapabilitySerializable<NBTBase>{

@CapabilityInject(Ideathloc.class)
public static final Capability<Ideathloc> DEATHLOC_CAP = null;
private Ideathloc instance = DEATHLOC_CAP.getDefaultInstance();

@Override
public boolean hasCapability(Capability<?> capability, EnumFacing facing) {
	return capability == DEATHLOC_CAP;
}

@Override
public <T> T getCapability(Capability<T> capability, EnumFacing facing) {
	return capability == DEATHLOC_CAP ? DEATHLOC_CAP.<T> cast(this.instance) : null;
}

@Override
public NBTBase serializeNBT() {
	return DEATHLOC_CAP.getStorage().writeNBT(DEATHLOC_CAP, this.instance, null);
}

@Override
public void deserializeNBT(NBTBase nbt) {
	DEATHLOC_CAP.getStorage().readNBT(DEATHLOC_CAP, this.instance, null, nbt);
}

}

deathHandler

package blazebeetle.capabilities;

import blazebeetle.mod.BlazeBeetle;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.util.ResourceLocation;
import net.minecraftforge.event.AttachCapabilitiesEvent;
import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;

public class deathHandler {

public static final ResourceLocation DEATHLOC_CAP = new ResourceLocation(BlazeBeetle.MODID, "deathloc");

@SubscribeEvent
public void attachCapability(AttachCapabilitiesEvent.Entity event){
	if (!(event.getEntity() instanceof EntityPlayer)){
		event.addCapability(DEATHLOC_CAP, new deathProvider());
	}
}

}

Animefan8888 · December 23, 2016

Post the crash.

Beetle90 · December 23, 2016

Post the crash.

---- Minecraft Crash Report ----
Time: 12/22/16 11:25 PM

Description: Ticking entity

java.lang.NullPointerException: Ticking entity

at blazebeetle.capabilities.deathProvider.<init>(deathProvider.java:13)

at blazebeetle.capabilities.deathHandler.attachCapability(deathHandler.java:16)

at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_6_deathHandler_attachCapability_Entity.invoke(.dynamic)

at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)

at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:185)

at net.minecraftforge.event.ForgeEventFactory.gatherCapabilities(ForgeEventFactory.java:565)

at net.minecraftforge.event.ForgeEventFactory.gatherCapabilities(ForgeEventFactory.java:550)

at net.minecraft.entity.Entity.<init>(Entity.java:252)

at net.minecraft.entity.item.EntityItem.<init>(EntityItem.java:54)

at net.minecraft.entity.item.EntityItem.<init>(EntityItem.java:67)

at net.minecraft.entity.Entity.entityDropItem(Entity.java:2008)

at net.minecraft.entity.Entity.dropItemWithOffset(Entity.java:1998)

at net.minecraft.entity.Entity.dropItem(Entity.java:1993)

at net.minecraft.entity.passive.EntityChicken.onLivingUpdate(EntityChicken.java:108)

at net.minecraft.entity.EntityLivingBase.onUpdate(EntityLivingBase.java:2225)

at net.minecraft.entity.EntityLiving.onUpdate(EntityLiving.java:342)

at net.minecraft.world.World.updateEntityWithOptionalForce(World.java:2111)

at net.minecraft.world.WorldServer.updateEntityWithOptionalForce(WorldServer.java:874)

at net.minecraft.world.World.updateEntity(World.java:2078)

at net.minecraft.world.World.updateEntities(World.java:1891)

at net.minecraft.world.WorldServer.updateEntities(WorldServer.java:646)

at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:783)

at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:687)

at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:156)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:536)

at java.lang.Thread.run(Thread.java:745)

A detailed walkthrough of the error, its code path and all known details is as follows:

---------------------------------------------------------------------------------------

-- Head --

Thread: Server thread

Stacktrace:

at blazebeetle.capabilities.deathProvider.<init>(deathProvider.java:13)

at blazebeetle.capabilities.deathHandler.attachCapability(deathHandler.java:16)

at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_6_deathHandler_attachCapability_Entity.invoke(.dynamic)

at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)

at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:185)

at net.minecraftforge.event.ForgeEventFactory.gatherCapabilities(ForgeEventFactory.java:565)

at net.minecraftforge.event.ForgeEventFactory.gatherCapabilities(ForgeEventFactory.java:550)

at net.minecraft.entity.Entity.<init>(Entity.java:252)

at net.minecraft.entity.item.EntityItem.<init>(EntityItem.java:54)

at net.minecraft.entity.item.EntityItem.<init>(EntityItem.java:67)

at net.minecraft.entity.Entity.entityDropItem(Entity.java:2008)

at net.minecraft.entity.Entity.dropItemWithOffset(Entity.java:1998)

at net.minecraft.entity.Entity.dropItem(Entity.java:1993)

at net.minecraft.entity.passive.EntityChicken.onLivingUpdate(EntityChicken.java:108)

at net.minecraft.entity.EntityLivingBase.onUpdate(EntityLivingBase.java:2225)

at net.minecraft.entity.EntityLiving.onUpdate(EntityLiving.java:342)

at net.minecraft.world.World.updateEntityWithOptionalForce(World.java:2111)

at net.minecraft.world.WorldServer.updateEntityWithOptionalForce(WorldServer.java:874)

at net.minecraft.world.World.updateEntity(World.java:2078)

-- Entity being ticked --

Details:

Entity Type: Chicken (net.minecraft.entity.passive.EntityChicken)

Entity ID: 143

Entity Name: Chicken

Entity's Exact location: -655.79, 4.00, 93.89

Entity's Block location: World: (-656,4,93), Chunk: (at 0,0,13 in -41,5; contains blocks -656,0,80 to -641,255,95), Region: (-2,0; contains chunks -64,0 to -33,31, blocks -1024,0,0 to -513,255,511)

Entity's Momentum: 0.00, -0.08, 0.00

Entity's Passengers: []

Entity's Vehicle: ~~ERROR~~ NullPointerException: null

Stacktrace:

at net.minecraft.world.World.updateEntities(World.java:1891)

at net.minecraft.world.WorldServer.updateEntities(WorldServer.java:646)

-- Affected level --

Details:

Level name: New World

All players: 0 total; []

Chunk stats: ServerChunkCache: 625 Drop: 0

Level seed: 787196711149034284

Level generator: ID 01 - flat, ver 0. Features enabled: true

Level generator options:

Level spawn location: World: (-714,4,71), Chunk: (at 6,0,7 in -45,4; contains blocks -720,0,64 to -705,255,79), Region: (-2,0; contains chunks -64,0 to -33,31, blocks -1024,0,0 to -513,255,511)

Level time: 12607 game time, 12607 day time

Level dimension: 0

Level storage version: 0x04ABD - Anvil

Level weather: Rain time: 14053 (now: false), thunder time: 66670 (now: false)

Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true

Stacktrace:

at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:783)

at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:687)

at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:156)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:536)

at java.lang.Thread.run(Thread.java:745)

-- System Details --

Details:

Minecraft Version: 1.10.2

Operating System: Windows 7 (amd64) version 6.1

Java Version: 1.8.0_111, Oracle Corporation

Java VM Version: Java HotSpot 64-Bit Server VM (mixed mode), Oracle Corporation

Memory: 677491520 bytes (646 MB) / 1037959168 bytes (989 MB) up to 1037959168 bytes (989 MB)

JVM Flags: 3 total; -Xincgc -Xmx1024M -Xms1024M

IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0

FML: MCP 9.32 Powered by Forge 12.18.3.2185 4 mods loaded, 4 mods active

States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored

UCHIJAAAA mcp{9.19} [Minecraft Coder Pack] (minecraft.jar)

UCHIJAAAA FML{8.0.99.99} [Forge Mod Loader] (forgeSrc-1.10.2-12.18.3.2185.jar)

UCHIJAAAA Forge{12.18.3.2185} [Minecraft Forge] (forgeSrc-1.10.2-12.18.3.2185.jar)

UCHIJAAAA blazebeetle{0.0.0} [blaze Beetle] (bin)

Loaded coremods (and transformers):

GL info: ~~ERROR~~ RuntimeException: No OpenGL context found in the current thread.

Profiler Position: N/A (disabled)

Player Count: 0 / 8; []

Type: Integrated Server (map_client.txt)

Is Modded: Definitely; Client brand changed to 'fml,forge'

Beetle90 · December 23, 2016

Just wanted to let everyone know that I've got it working after changing a lot of the code. I may run into more issues when I push this to multiplayer, but if anyone needs help regarding the solution, just PM me!

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[1.10.2] Understanding Capabilities

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