So it wasn't very clear to put that in words in the title, so here is a better explanation. I have a sword and I want it only to hurt enemies. I can distinguish between enemies and not enemies, but how do I make it not hurt non-enemies?

This probably isn't perfect practice, but what I would do is create a Mixin and mix into the LivingEntity#hurt(DamageSource, float) class and add the following check:

• DamageSource is Entity
  • If so, check if the entity is holding the sword.
  • Any other conditions, such as making sure the entity is a player.

If the check above is true, return false.

Something like this:

package com.example.examplemod.mixin;

import com.example.examplemod.Mod;
import net.minecraft.world.damagesource.DamageSource;
import net.minecraft.world.entity.Entity;
import net.minecraft.world.entity.EntityType;
import net.minecraft.world.entity.EquipmentSlot;
import net.minecraft.world.entity.LivingEntity;
import org.spongepowered.asm.mixin.Mixin;
import org.spongepowered.asm.mixin.injection.At;
import org.spongepowered.asm.mixin.injection.Inject;
import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;

@Mixin(LivingEntity.class)
public abstract class SuperCoolSwordThing {
    @Inject(method="hurt(Lnet/minecraft/world/damagesource/DamageSource;F)Z", at = @At("HEAD"), cancellable = true)
    private void superCoolSword_onlyDamageEnemy(DamageSource p_21016_, float p_21017_, CallbackInfoReturnable<Boolean> cir) {
        if (p_21016_.getEntity()!=null&&p_21016_.getEntity() instanceof LivingEntity&&((LivingEntity)p_21016_.getEntity()).getMainHandItem().is(Mod.SUPERCOOLSWORD) && Mod.checkIsEntity((LivingEntity)(Object)this)) {
            cir.setReturnValue(false);
        }
    }
}

I will remind you that this probably isn't professional and that there are probably better ways to do it. (This is just how I would do it.)

Edited April 13, 20232 yr by Hipposgrumm
See warjort's answer.

AttackEntityEvent, LivingAttackEvent or LivingHurtEvent.

Which one you use depends upon on what you are trying to achieve.

e.g. the first is only for players that are attacking

while the last one is generally used to change the damage amount, which you could set to 0 but it will still show the animations.

Edited April 13, 20232 yr by warjort

Quote

I will remind you that this probably isn't professional

Please don't encourage people to use mixins.

They are a last resort for special behaviour can't be achieved in safer ways.

e.g. stuff that forge would be unlikely to include as an event because it is just too niche of a usecase

I am using the hurt entity method and it doesn't have AttackEntityEvent, LivingAttackEvent, or LivingHurtEvent. Do I create a new one or change methods?

https://forge.gemwire.uk/wiki/Events