Block Damage From Specific DamageSource

[Achilleus117]

I am making a mod that has an item that spawns lightning when used. The lightning is used to attack other entities. I need to block damage from the lightning to just the player. How can I achieve this? I know lightning is one of the DamageSources, is there a way to just block this DamageSource for the user holding the item?

[poopoodice]

LivingHurtEvent and check if the damage source is lightning, cancel the event.

[Achilleus117]

Here (https://mcforge.readthedocs.io/en/latest/events/intro/#canceling) it says to call Event#setCanceled to cancel an event, but how do I check it first? Also, where should I be calling it? Every tick? 

[poopoodice]

That's not how events work, there's introduction of setting events in the link.

[Achilleus117]

My bad, realized I missed that as soon as I posted that. I made a handler and set it to disable damage when the source was lightning. The problem is that it disables the damage for everybody, how can I make it just disable it when my custom item is being held? 

[Achilleus117]

I set a static LIvingEntity variable on the handler class and set it to the player entity and checked the damage against that, it works but it doesn't seem like the cleanest solution. 

[poopoodice]

The event provides an entity, and you can't store data like that.

[Achilleus117]

The event provides the entity that is being hit, not the entity that is holding my item. Storing the data like that is working, but once the item is dropped it will still block the damage to the player

[Draco18s]

You have to get that from the event too. Its in the event's DamageSource's data.

Because think about it, if you store a static entity reference, what entity is that? It can't be "the entity that dealt damage" because there are MANY entities that could do that.

Edited August 12, 2020 by Draco18s

[Achilleus117]

28 minutes ago, Draco18s said:

You have to get that from the event too. Its in the event's DamageSource's data.

Because think about it, if you store a static entity reference, what entity is that? It can't be "the entity that dealt damage" because there are MANY entities that could do that.

The DamageSource's data says which entity is holding my custom item? Which property is that? The entity that dealt the damage was the lightning bolt. That's not what I need. I need the entity that is holding my custom item. Using the static entity is working, but it stops the player (and only the player) from ever receiving lightning damage even after dropping the item. 

[Draco18s]

1 hour ago, Achilleus117 said:

The DamageSource's data says which entity is holding my custom item? Which property is that? The entity that dealt the damage was the lightning bolt. That's not what I need. I need the entity that is holding my custom item. Using the static entity is working, but it stops the player (and only the player) from ever receiving lightning damage even after dropping the item. 

Ah yes.  Normally you would be able to call getTrueSource.

But as lightning doesn't normally get spawned by entities (unlike arrows) they don't track an owner. 

 

You will be unable to track this information. 

 

You may be able to get nearby players and check their active item, but this is at best a guess as to which player was actually responsible. 

Edited August 12, 2020 by Draco18s

[Achilleus117]

On 8/12/2020 at 1:56 AM, diesieben07 said:

Considering it's your own item that spawns the lightning you need to attach this "owner" information yourself.

When spawning the LightningBoltEntity you can use either a capability attached to it or use getPersistentData. The latter is a little ugly, because you are working with raw NBT, only use it for small amounts of data. Also make sure to include your ModID in the keys that you use, otherwise there can be collisions with other mods.

I actually made my own type of LightningBoltEntity that extends LightningBoltEntity, I guess it may be a bit easier to pass the information to that? 

[Beethoven92]

There is a "caster" field inside LightningBoltEntity which stores a ServerPlayerEntity, and you can set this field with the setCaster method. Now...when in your item class you create the bolt entity, you can set its caster to the player that is holding the item. Then you would need to retrieve the caster of the bolt in your event handler. Problem, the "caster" field is private and you would have to use access transformers to make it public. I am not sure if this would work though..