How to perform an operation on the server side through the Event Handler?

Greyscail · November 13, 2017

I have this for my Event Handler class:

public class ModEventHandler
{
	@SubscribeEvent
	public static void dualWield(MouseEvent event)
	{
      	// bunch of code
      
      	boolean isSuccessfulAttack = target.attackEntityFrom(DamageSource.causePlayerDamage(player), damage);
      
      	// bunch of code
	}
}

Registered as follows:

@EventHandler
	public void preInit(FMLInitializationEvent event)
	{
		MinecraftForge.EVENT_BUS.register(ModEventHandler.class);
	}

Where I've basically copied the code minecraft uses when you left click except I've altered it to allow attacking with the offhand weapon. My issue is that the line of code responsible for actually doing the damage seemingly only works when called from the server side. I have no clue how to remedy this, I've tried putting:

public class ModEventHandler
{
	@SideOnly(Side.SERVER)
	@SubscribeEvent
	public static void dualWield(MouseEvent event)
	{
      	// bunch of code
      
      	boolean isSuccessfulAttack = target.attackEntityFrom(DamageSource.causePlayerDamage(player), damage);
      
      	// bunch of code
	}
}

But that just crashes. The issue I'm having is how should I call something from the server if it is running in my Event Handler?

Greyscail · November 13, 2017

Just now, diesieben07 said:

You don't understand the difference between logical and physical side. Once again: read and understand the documentation. If you have questions, ask.

You need packets.

hehe, I'm just more of a learn by example type of person rather than the type to dig through an instruction manual, had I ever seen packets being used then I'd have probably figured that out sooner

Differentiation · November 13, 2017

22 minutes ago, Greyscail said:
I have this for my Event Handler class:
public class ModEventHandler
{
	@SubscribeEvent
	public static void dualWield(MouseEvent event)
	{
      	// bunch of code
      
      	boolean isSuccessfulAttack = target.attackEntityFrom(DamageSource.causePlayerDamage(player), damage);
      
      	// bunch of code
	}
}
Registered as follows:
@EventHandler
	public void preInit(FMLInitializationEvent event)
	{
		MinecraftForge.EVENT_BUS.register(ModEventHandler.class);
	}
Where I've basically copied the code minecraft uses when you left click except I've altered it to allow attacking with the offhand weapon. My issue is that the line of code responsible for actually doing the damage seemingly only works when called from the server side. I have no clue how to remedy this, I've tried putting:
public class ModEventHandler
{
	@SideOnly(Side.SERVER)
	@SubscribeEvent
	public static void dualWield(MouseEvent event)
	{
      	// bunch of code
      
      	boolean isSuccessfulAttack = target.attackEntityFrom(DamageSource.causePlayerDamage(player), damage);
      
      	// bunch of code
	}
}
But that just crashes. The issue I'm having is how should I call something from the server if it is running in my Event Handler?

Some events are only read by the logical client, or logical server, or both, depending on the result of the event. Therefore, if only a client responds, you need to send packets to the logical server telling it to perform certain code that the client is not responsible for performing, like @diesieben07 mentioned.

NOTE: if you perform server-side code on client-side, it may not work... packets...

Edited November 13, 2017 by Differentiation

Greyscail · November 14, 2017

3 hours ago, Differentiation said:

Some events are only read by the logical client, or logical server, or both, depending on the result of the event. Therefore, if only a client responds, you need to send packets to the logical server telling it to perform certain code that the client is not responsible for performing, like @diesieben07 mentioned.

NOTE: if you perform server-side code on client-side, it may not work... packets...

Ok I've set all that up and works to an extent except the problem hasn't been solved, I have:

boolean isSuccessfulAttack = target.attackEntityFrom(DamageSource.causePlayerDamage(player), damage);

System.out.println(Thread.currentThread().getName());

And the console says Server Thread but target.attackEntiityFrom() still returns false

Differentiation · November 14, 2017

30 minutes ago, Greyscail said:

target.attackEntityFrom(DamageSource.causePlayerDamage(player), damage)

Is this a boolean statement?

Can you please show us ALL the code you have so that we can help?

You might also want to incorporate this code to check for the running side:

public class SideTest //Not the name I recommend, nor do I have this name, but incorporate the below method in some class...
{
	public static void getSide(World worldIn)
	{
		if (worldIn.isRemote)
		{
    			System.out.println("CLIENT");
		}

		if (!worldIn.isRemote)
		{
          		System.out.println("SERVER"); //These show as the color RED in the client as info, so it's easy to see!
		}
    	}
}

And then where ever you want to test for the side, you call this static method.

This is how I test the running thread on my mod.

If the server is NOT running, then the boolean statement will not run and will automatically return false since the server did not read it, of course. Then this means that you need to send a packet to the server.

I hope I made things a bit more clear!

Try what I told you, then respond with the results

If you're still having trouble

Oh, and lastly, please don't use @SideOnly(Side.SERVER) or @SideOnly(Side.CLIENT), they don't help in this context.

Edited November 14, 2017 by Differentiation

Differentiation · November 14, 2017

4 hours ago, Greyscail said:

public static void dualWield(MouseEvent event)

Why the static? Explain.

Greyscail · November 14, 2017

1 minute ago, Differentiation said:
Is this a boolean statement?

Can you please show us ALL the code you have so that we can help?

You might also want to incorporate this code to check for the running side:
if (worldIn.isRemote)
{
    System.out.println("CLIENT");
}

if (!worldIn.isRemote)
{
    System.out.println("SERVER");
}
If the server is NOT running, then the boolean statement will not run and will automatically return false since the server did not read it, of course. Then this means that you need to send a packet to the server.

I hope I made things a bit more clear!

Try what I told you, then respond with the results

And lastly, please don't use @SideOnly(Side.SERVER) or @SideOnly(Side.CLIENT), they don't help in this context.

Yea it's a boolean, and I'm hesitant to show all of my code because it'd be a huge mess with how spread out it is. And yea, it definitely says client side using the method showed me which is annoying because I'm certain I set the message system up properly and it definitely says Server Thread when I ran:

System.out.println(Thread.currentThread().getName());

Greyscail · November 14, 2017

4 minutes ago, Differentiation said:

Why the static? Explain.

Erm, well you could call it a force of habit. At least in my mind it functions as a static method even though it doesn't make a difference

Differentiation · November 14, 2017

1 minute ago, Greyscail said:
Yea it's a boolean, and I'm hesitant to show all of my code because it'd be a huge mess with how spread out it is. And yea, it definitely says client side using the method showed me which is annoying because I'm certain I set the message system up properly and it definitely says Server Thread when I ran:
System.out.println(Thread.currentThread().getName());

I mean, my method would, in this case, be more accurate... and, since you're getting false for the boolean, and the fact that my method says CLIENT, then only the client runs, which means you need to start sending packets!

Differentiation · November 14, 2017

1 minute ago, Greyscail said:

Erm, well you could call it a force of habit. At least in my mind it functions as a static method even though it doesn't make a difference

If that's okay with you!

Differentiation · November 14, 2017

By the way, do you know how to handle packets? Because if not, I have a great tutorial that I found by MineMaarten which is an excellent modder that explains how all this works.

Differentiation · November 14, 2017

@jabelar put in your thoughts into this, please!

Edited November 14, 2017 by Differentiation

Greyscail · November 14, 2017

public class ModEventHandler
{
	private static final int LMB = 0, RMB = 1;

	private static enum WEAPON
	{
		ItemSword, ItemAxe
	}

	@SubscribeEvent
	public void dualWield(MouseEvent event)
	{
		if (event.isButtonstate())
		{
			Minecraft minecraft = Minecraft.getMinecraft();

			EntityPlayerSP player = minecraft.player;

			ItemStack mainhand = player.getHeldItem(EnumHand.MAIN_HAND);
			ItemStack offhand = player.getHeldItem(EnumHand.OFF_HAND);

			String primaryType = mainhand.getItem().getClass().getSimpleName();
			String secondaryType = offhand.getItem().getClass().getSimpleName();

			try
			{
				WEAPON.valueOf(primaryType);
				WEAPON.valueOf(secondaryType);
			}
			catch (IllegalArgumentException e)
			{
				return;
			}

			if (event.getButton() == RMB)
			{
				if (!minecraft.player.isRowingBoat())
				{
					switch (minecraft.objectMouseOver.typeOfHit)
					{
					case ENTITY:

						// minecraft.playerController.attackEntity(player,
						// minecraft.objectMouseOver.entityHit);

						// minecraft.playerController.syncCurrentPlayItem();

						if (minecraft.playerController.getCurrentGameType() != GameType.SPECTATOR)
						{
							AttackHandler.attackQueue.add(new Attack(player, minecraft.objectMouseOver.entityHit));

							ExampleMod.INSTANCE.registerMessage(ModMessageHandler.class, ModMessage.class, ExampleMod.id++, Side.SERVER);
							ExampleMod.INSTANCE.sendToServer(new ModMessage(ModMessageHandler.DO_ATTACK));
						}

						break;

					case BLOCK:

						BlockPos blockpos = minecraft.objectMouseOver.getBlockPos();

						if (!minecraft.world.isAirBlock(blockpos))
						{
							minecraft.playerController.clickBlock(blockpos, minecraft.objectMouseOver.sideHit);

							break;
						}

					case MISS:

						minecraft.player.resetCooldown();

						net.minecraftforge.common.ForgeHooks.onEmptyLeftClick(player);
					}
				}

				player.setActiveHand(EnumHand.OFF_HAND);
				player.swingArm(EnumHand.OFF_HAND);
			}
		}
	}
}

public class ModMessageHandler implements IMessageHandler<ModMessage, IMessage>
{
	public static final int DO_ATTACK = 0;
	
	@Override
	public IMessage onMessage(ModMessage message, MessageContext ctx)
	{
		EntityPlayerMP serverPlayer = ctx.getServerHandler().player;

		int code = message.code;

		serverPlayer.getServerWorld().addScheduledTask(() ->
		{
			switch (code)
			{
			case DO_ATTACK:

				AttackHandler.attack();
				
				break;

			default:

				break;
			}
		});

		return null;
	}
}

public class AttackHandler
{
	public static final ArrayList<Attack> attackQueue = new ArrayList<Attack>();

	public static void attack()
	{
		Attack attack = attackQueue.get(0);

		attack(attack.getAttacker(), attack.getAttacked());

		attackQueue.remove(0);
	}

	public static void attack(EntityPlayer player, Entity target)
	{
		if (!net.minecraftforge.common.ForgeHooks.onPlayerAttackTarget(player, target)) return;
		if (target.canBeAttackedWithItem())
		{
			if (!target.hitByEntity(player))
			{
				float damage = (float) player.getEntityAttribute(SharedMonsterAttributes.ATTACK_DAMAGE).getAttributeValue();
				float enchantmentModifier;

				if (target instanceof EntityLivingBase)
				{
					enchantmentModifier = EnchantmentHelper.getModifierForCreature(player.getHeldItem(EnumHand.OFF_HAND), ((EntityLivingBase) target).getCreatureAttribute());
				}
				else
				{
					enchantmentModifier = EnchantmentHelper.getModifierForCreature(player.getHeldItem(EnumHand.OFF_HAND), EnumCreatureAttribute.UNDEFINED);
				}

				float swingModifier = player.getCooledAttackStrength(0.5F);

				damage *= (0.2F + swingModifier * swingModifier * 0.8F);
				enchantmentModifier *= swingModifier;

				player.resetCooldown();

				if (damage > 0.0F || enchantmentModifier > 0.0F)
				{
					boolean isFullSwing = swingModifier > 0.9F;
					boolean isKnockbackStrike = false;

					int knockbackLevel = EnchantmentHelper.getKnockbackModifier(player);

					if (player.isSprinting() && isFullSwing)
					{
						player.world.playSound((EntityPlayer) null, player.posX, player.posY, player.posZ, SoundEvents.ENTITY_PLAYER_ATTACK_KNOCKBACK, player.getSoundCategory(), 1.0F, 1.0F);

						++knockbackLevel;

						isKnockbackStrike = true;
					}

					boolean isCriticalStrike = isFullSwing && player.fallDistance > 0.0F && !player.onGround && !player.isOnLadder() && !player.isInWater() && !player.isPotionActive(MobEffects.BLINDNESS) && !player.isRiding() && target instanceof EntityLivingBase;

					// isCriticalStrike = isCriticalStrike && !player.isSprinting();
					isCriticalStrike &= !player.isSprinting();

					net.minecraftforge.event.entity.player.CriticalHitEvent hitResult = net.minecraftforge.common.ForgeHooks.getCriticalHit(player, target, isCriticalStrike, isCriticalStrike ? 1.5F : 1.0F);

					isCriticalStrike = hitResult != null;

					if (isCriticalStrike)
					{
						damage *= hitResult.getDamageModifier();
					}

					damage = damage + enchantmentModifier;

					boolean isSweepingStrike = false;

					double d0 = (double) (player.distanceWalkedModified - player.prevDistanceWalkedModified);

					if (isFullSwing && !isCriticalStrike && !isKnockbackStrike && player.onGround && d0 < (double) player.getAIMoveSpeed())
					{
						ItemStack itemstack = player.getHeldItem(EnumHand.OFF_HAND);

						if (itemstack.getItem() instanceof ItemSword)
						{
							isSweepingStrike = true;
						}
					}

					float targetHealth = 0.0F;

					boolean hasSetFire = false;

					int fireaspectModifier = EnchantmentHelper.getFireAspectModifier(player);

					if (target instanceof EntityLivingBase)
					{
						targetHealth = ((EntityLivingBase) target).getHealth();

						if (fireaspectModifier > 0 && !target.isBurning())
						{
							hasSetFire = true;

							target.setFire(1);
						}
					}

					double d1 = target.motionX;
					double d2 = target.motionY;
					double d3 = target.motionZ;

					if (target.getEntityWorld().isRemote)
					{
					    System.out.println("CLIENT");
					}

					if (!target.getEntityWorld().isRemote)
					{
					    System.out.println("SERVER");
					}
					
					boolean isSuccessfulAttack = ((EntityLivingBase) target).attackEntityFrom(DamageSource.causePlayerDamage(player), damage);

					target.performHurtAnimation();

					if (isSuccessfulAttack)
					{
						if (knockbackLevel > 0)
						{
							if (target instanceof EntityLivingBase)
							{
								((EntityLivingBase) target).knockBack(player, (float) knockbackLevel * 0.5F, (double) MathHelper.sin(player.rotationYaw * 0.017453292F), (double) (-MathHelper.cos(player.rotationYaw * 0.017453292F)));
							}
							else
							{
								target.addVelocity((double) (-MathHelper.sin(player.rotationYaw * 0.017453292F) * (float) knockbackLevel * 0.5F), 0.1D, (double) (MathHelper.cos(player.rotationYaw * 0.017453292F) * (float) knockbackLevel * 0.5F));
							}

							player.motionX *= 0.6D;
							player.motionZ *= 0.6D;
							player.setSprinting(false);
						}

						if (isSweepingStrike)
						{
							float areaDamage = 1.0F + EnchantmentHelper.getSweepingDamageRatio(player) * damage;

							for (EntityLivingBase entitylivingbase : player.world.getEntitiesWithinAABB(EntityLivingBase.class, target.getEntityBoundingBox().grow(1.0D, 0.25D, 1.0D)))
							{
								if (entitylivingbase != player && entitylivingbase != target && !player.isOnSameTeam(entitylivingbase) && player.getDistanceSqToEntity(entitylivingbase) < 9.0D)
								{
									entitylivingbase.knockBack(player, 0.4F, (double) MathHelper.sin(player.rotationYaw * 0.017453292F), (double) (-MathHelper.cos(player.rotationYaw * 0.017453292F)));
									entitylivingbase.attackEntityFrom(DamageSource.causePlayerDamage(player), areaDamage);
								}
							}

							player.world.playSound((EntityPlayer) null, player.posX, player.posY, player.posZ, SoundEvents.ENTITY_PLAYER_ATTACK_SWEEP, player.getSoundCategory(), 1.0F, 1.0F);
							player.spawnSweepParticles();
						}

						if (target instanceof EntityPlayerMP && target.velocityChanged)
						{
							((EntityPlayerMP) target).connection.sendPacket(new SPacketEntityVelocity(target));
							target.velocityChanged = false;
							target.motionX = d1;
							target.motionY = d2;
							target.motionZ = d3;
						}

						if (isCriticalStrike)
						{
							player.world.playSound((EntityPlayer) null, player.posX, player.posY, player.posZ, SoundEvents.ENTITY_PLAYER_ATTACK_CRIT, player.getSoundCategory(), 1.0F, 1.0F);
							player.onCriticalHit(target);
						}

						if (!isCriticalStrike && !isSweepingStrike)
						{
							if (isFullSwing)
							{
								player.world.playSound((EntityPlayer) null, player.posX, player.posY, player.posZ, SoundEvents.ENTITY_PLAYER_ATTACK_STRONG, player.getSoundCategory(), 1.0F, 1.0F);
							}
							else
							{
								player.world.playSound((EntityPlayer) null, player.posX, player.posY, player.posZ, SoundEvents.ENTITY_PLAYER_ATTACK_WEAK, player.getSoundCategory(), 1.0F, 1.0F);
							}
						}

						if (enchantmentModifier > 0.0F)
						{
							player.onEnchantmentCritical(target);
						}

						player.setLastAttackedEntity(target);

						if (target instanceof EntityLivingBase)
						{
							EnchantmentHelper.applyThornEnchantments((EntityLivingBase) target, player);
						}

						EnchantmentHelper.applyArthropodEnchantments(player, target);

						ItemStack weapon = player.getHeldItem(EnumHand.OFF_HAND);

						Entity entity = target;

						if (target instanceof MultiPartEntityPart)
						{
							IEntityMultiPart ientitymultipart = ((MultiPartEntityPart) target).parent;

							if (ientitymultipart instanceof EntityLivingBase)
							{
								entity = (EntityLivingBase) ientitymultipart;
							}
						}

						if (!weapon.isEmpty() && entity instanceof EntityLivingBase)
						{
							ItemStack beforeHitCopy = weapon.copy();
							weapon.hitEntity((EntityLivingBase) entity, player);

							if (weapon.isEmpty())
							{
								net.minecraftforge.event.ForgeEventFactory.onPlayerDestroyItem(player, beforeHitCopy, EnumHand.OFF_HAND);
								player.setHeldItem(EnumHand.OFF_HAND, ItemStack.EMPTY);
							}
						}

						if (target instanceof EntityLivingBase)
						{
							float f5 = targetHealth - ((EntityLivingBase) target).getHealth();
							player.addStat(StatList.DAMAGE_DEALT, Math.round(f5 * 10.0F));

							if (fireaspectModifier > 0)
							{
								target.setFire(fireaspectModifier * 4);
							}

							if (player.world instanceof WorldServer && f5 > 2.0F)
							{
								int k = (int) ((double) f5 * 0.5D);
								((WorldServer) player.world).spawnParticle(EnumParticleTypes.DAMAGE_INDICATOR, target.posX, target.posY + (double) (target.height * 0.5F), target.posZ, k, 0.1D, 0.0D, 0.1D, 0.2D);
							}
						}

						player.addExhaustion(0.1F);
					}
					else
					{
						player.world.playSound((EntityPlayer) null, player.posX, player.posY, player.posZ, SoundEvents.ENTITY_PLAYER_ATTACK_NODAMAGE, player.getSoundCategory(), 1.0F, 1.0F);

						if (hasSetFire)
						{
							target.extinguish();
						}
					}
				}
			}
		}
	}

	public static class Attack
	{
		EntityPlayer attacker;
		Entity attacked;

		public Attack(EntityPlayer attacker, Entity attacked)
		{
			this.attacker = attacker;
			this.attacked = attacked;
		}

		public EntityPlayer getAttacker()
		{
			return attacker;
		}

		public Entity getAttacked()
		{
			return attacked;
		}
	}
}

@Differentiation Erm that's my code I really don't know what's wrong...

Differentiation · November 14, 2017

By the way! What version are you using? Just curious.

Differentiation · November 14, 2017

1 minute ago, Greyscail said:

Minecraft minecraft = Minecraft.getMinecraft();

This is client-side. Server code does not read from here on.

Differentiation · November 14, 2017

2 minutes ago, Greyscail said:

boolean isSuccessfulAttack = ((EntityLivingBase) target).attackEntityFrom(DamageSource.causePlayerDamage(player), damage);

Will not work, since server does not read it.

Greyscail · November 14, 2017

1 minute ago, Differentiation said:

This is client-side. Server code does not read from here on.

But I thought it wouldn't matter since that was all from before:

AttackHandler.attackQueue.add(new Attack(player, minecraft.objectMouseOver.entityHit));

ExampleMod.INSTANCE.registerMessage(ModMessageHandler.class, ModMessage.class, ExampleMod.id++, Side.SERVER);
ExampleMod.INSTANCE.sendToServer(new ModMessage(ModMessageHandler.DO_ATTACK));

I thought everything before that wouldn't matter

Differentiation · November 14, 2017

4 minutes ago, Greyscail said:

@Differentiation Erm that's my code I really don't know what's wrong...

Are you JOKING??!!!!! A whole ton is wrong! Your code is mixed client and server-side code, which is NOT GOOD and may cause CRASHES or ghosting or bad things!

Differentiation · November 14, 2017

2 minutes ago, Greyscail said:

I thought everything before that wouldn't matter

What do you mean "before that"? Your code is clearly mixed there!

Differentiation · November 14, 2017

It's a bit ambiguous, especially for me, being an old man and all, skimming through these large chunks of code. I'll need the help of others. @jabelar, please. @Draco18s

Edited November 14, 2017 by Differentiation

Greyscail · November 14, 2017

Just now, Differentiation said:

What do you mean "before that"? Your code is clearly mixed there!

I still don't get it, how is it mixed? The only line of code that I'm having issues with is:

boolean isSuccessfulAttack = ((EntityLivingBase) target).attackEntityFrom(DamageSource.causePlayerDamage(player), damage);

And I was told that it needed to be called from the server side. The way you're making it sound is like everything I wrote needs to be called from the server side. For one, the first class where the bulk of the code is, is my Event Handler so I couldn't make that server side even if I wanted to

Differentiation · November 14, 2017

2 minutes ago, Greyscail said:


boolean isSuccessfulAttack = ((EntityLivingBase) target).attackEntityFrom(DamageSource.causePlayerDamage(player), damage);

ONLY this is supposed to be sent to the server, NOT the whole method.

Edited November 14, 2017 by Differentiation

Greyscail · November 14, 2017

2 minutes ago, Differentiation said:

It's a bit ambiguous, especially for me, being an old man and all, skimming through these large chunks of code. I'll need the help of others. @jabelar, please. @Draco18s

That's why I didn't want to include it from the beginning hehe

Differentiation · November 14, 2017

1 minute ago, Greyscail said:

That's why I didn't want to include it from the beginning hehe

ya... you only need to notify the server of that boolean statement at that specific time.

This can easily be accomplished via player capabilities.

Edited November 14, 2017 by Differentiation

Greyscail · November 14, 2017

Just now, Differentiation said:

ONLY this is supposed to be sent to the server, NOT the whole method.

Yea but from what I saw on the docs:

public class ModMessage implements IMessage
{
	public ModMessage()
	{
	}

	protected int code;

	public ModMessage(int code)
	{
		this.code = code;
	}

	@Override
	public void toBytes(ByteBuf buf)
	{
		buf.writeInt(code);
	}

	@Override
	public void fromBytes(ByteBuf buf)
	{
		code = buf.readInt();
	}
}

The only thing I send as a message to the server is an integer...? I didn't know how to cal a function with just an integer and all that code is what I came up with

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