Prevent Player From Attacking or Damaging Certain Monsters?

[SubjectsNotEncrypted]

Is there a way with Decorate and/or Zscript to prevent attacks, or at least damage, to friendly actors? Or even just actors with a certain TID?

I've read +GHOST and +THRUGHOST may help. Just not clear how that can be done while still allowing the actor to be damaged by other monsters or other player classes.

[DeonteLangworth]

To prevent attacks or damage to friendly actors, you can set the CollisionType property of the actor to a unique string value, and then set the CollisionGroup property of other actors to the same string value. This will allow the actors to pass through each other without causing damage.

Here’s an example of how to use CollisionType and CollisionGroup properties to prevent attacks or damage to friendly actors:

Actor FriendlyActor : DoomActor
{
+FRIENDLY
CollisionType "Friendly"
}

Actor EnemyActor : DoomActor
{
CollisionGroup "Friendly"
}

In this example, FriendlyActor is set as a friendly actor by using the +FRIENDLY flag. The CollisionType property of FriendlyActor is set to "Friendly". The CollisionGroup property of EnemyActor is set to "Friendly". This will allow EnemyActor to pass through FriendlyActor without causing damage.

[Jarewill]

CollisionType and CollisionGroup aren't valid actor properties, was that message written by an AI?

As for the question itself, you can do that in ZScript by overriding DamageMobj in the monster actor and checking if it has the friendly flag and if the damage source is the player.
Or using inventory items and ModifyDamage if you don't want to replace monster classes, you can automatically give each monster that item using an event handler.
For example:

Code: Select all

Class FriendlyDamageHandler : EventHandler{
	Override void WorldThingSpawned(WorldEvent e){
		If(e.Thing.bISMONSTER && e.Thing.bFRIENDLY){ //This checks if a friendly monster spawned
			e.Thing.GiveInventory("FriendlyDamagePrevent",1); //And gives them this item
		}
	}
}
Class FriendlyDamagePrevent : Inventory{
	Override void ModifyDamage(int damage, Name damageType, out int newdamage, bool passive, Actor inflictor, Actor source, int flags){
		If(passive && source is "PlayerPawn"){ //This checks if the monster took damage by a player
			newdamage = 0; //And nullifies all damage
			Return;
		}
	}
}

[SubjectsNotEncrypted]

thanks jarewill

though overriding the DamageMobj method on the class doesn't seem to stop blood splatter on the target actor
is there a way to prevent the splatter too?

[Jarewill]

For that you have to override SpawnLineAttackBlood in the monster class:

Code: Select all

	Override void SpawnLineAttackBlood(Actor attacker, Vector3 bleedpos, double SrcAngleFromTarget, int originaldamage, int actualdamage){
		If(attacker is "PlayerPawn" && actualdamage==0){Return;} //If player attacked and the damage was 0, don't spawn anything.
		Super.SpawnLineAttackBlood(attacker,bleedpos,SrcAngleFromTarget,originaldamage,actualdamage);
	}

[inkoalawetrust]

To prevent attacks or damage to friendly actors, you can set the CollisionType property of the actor to a unique string value, and then set the CollisionGroup property of other actors to the same string value. This will allow the actors to pass through each other without causing damage.

Here’s an example of how to use CollisionType and CollisionGroup properties to prevent attacks or damage to friendly actors:

Actor FriendlyActor : DoomActor
{
+FRIENDLY
CollisionType "Friendly"
}

Actor EnemyActor : DoomActor
{
CollisionGroup "Friendly"
}

In this example, FriendlyActor is set as a friendly actor by using the +FRIENDLY flag. The CollisionType property of FriendlyActor is set to "Friendly". The CollisionGroup property of EnemyActor is set to "Friendly". This will allow EnemyActor to pass through FriendlyActor without causing damage.

No ChatGPT, GZDoom has no such properties, only the ThruBits property allows for collision groups like that. Although it would definitely be nice to not just have 32 possible collision groups, since that is very limited.