Zdoom - How to prevent monsters to attack each other ?

Hello guys,

I notice that some monsters start fighting each other because one accidentally hit another monster. There is a way to prevent monsters to injuring each other or make monsters invulnerable between them ? :)

Thing Hate? I think there are like six options for targets.

Create a ZMAPINFO entry for the level and add "NoInfighting" to its definition. This will completely disable infighting, however, so if what you're asking for is to disable it on a case-for-case basis, then I dunno.

There are several ways to disable infighting, yes. See these articles for information:
http://doomwiki.org/wiki/Monster_infighting
http://zdoom.org/wiki/Infight

Note that disabling infighting will make monsters unable to target each other, but not make them invulnerable to each other's attacks. In other words, if there were 2 monsters (A and B) attacking the player, and monster A throwed a fireball towards the player, but the fireball hits monster B on its way, then monster B would take damage (lose health points), but continue attacking the player (not turning to fight against monster A).

Another thing: Projectile-based attacks don't deal any damage when they hit a monster of the same monster species as the monster who fired the projectile. Other types of attacks than projectile-based ones deal damage even to monsters of the same type as the attacker, though.