[since old times] A morphprojectile affects allied players

[Edward-san]

From zandronum bug ticket 2905.

It's present an example wad. Load it, summon Chickengun, make sure switch on pickup is on, pick the weapon, summon a bot and fire the weapon against it.

Question: is that inherited from Heretic/Hexen or a mistake by ZDoom? If it should be fixed, should friend actors, too, be immune to morphing?

[Graf Zahl]

Think about what a normal projectile does to an allied player. This should behave identically, i.e. if the normal projectile hurts, this one should morph, if the normal one does not, it shouldn't morph. I can't recall right now what options exist here.

[Edward-san]

AFAIR the only way to damage an allied player is when 'team damage' is on. So the bug here is that morphing is done even if 'team damage' is off.

[Rachael]

Question: is that inherited from Heretic/Hexen or a mistake by ZDoom?

Team Damage is something new to ZDoom, it did not even exist in Heretic/Hexen, so in that game you always had the ability to damage other players as well as morphing them, as far as I know.

I doubt there's many mods that depend on the present behavior, but fixing this may require additional actor flags, IMO, because you may want "friend morph" projectiles (i.e. give a fellow player a "superman" morph in a coop game).

[Ed the Bat]

...you may want "friend morph" projectiles (i.e. give a fellow player a "superman" morph in a coop game).

The issue of 'good' morphs vs 'bad' morphs is one that already could stand to be re-evaluated. For instance, the DONTMORPH flag is absolute, even if a modder would want an actor protected from bad morphs but still able to collect good morphs. Some more control would be very desirable. The fact that PowerMorph even exists means there's already supposed to be some distinction between good and bad morphs.

[Edward-san]

I have a fix for the allied players, though, as always, the function to change is the messed one. I'll make a PR for that.

[edit] Done. When team damage is off, the projectile passes through the allied player, but I don't know if it makes sense.

[Graf Zahl]

I don't like how you did it. Shouldn't this be part of AMorphProjectile::DoSpecialDamage?

[Edward-san]

The virtual function DoSpecialDamage doesn't pass the source. Should I add it as a parameter?

[Graf Zahl]

The source of the projectile or the damage inflictor? Isn't projectile->target enough?

[Edward-san]

I mean literally 'source', one of the parameters of P_DamageMobj, because that's what's used when checking for teammates. If you say 'inflictor->target' is enough, why is 'source' used?

[Graf Zahl]

Because it may matter in other situations, but in the case of a projectile hitting a shootable actor it's the same thing, if you examine the one single relevant call to this function responsible here.

p_map.cpp line 1383: int newdam = P_DamageMobj(thing, tm.thing, tm.thing->target, damage, tm.thing->DamageType);

[Edward-san]

Updated. One funny part is that it's possible to make the player morph by making it fire against its voodoo doll counterpart. Also it ignores invulnerabilities, but I guess that's okay.

[Graf Zahl]

Updated. One funny part is that it's possible to make the player morph by making it fire against its voodoo doll counterpart.

Yes, and there's mods which actually depend on it!

[Graf Zahl]

And where's the update?

[Edward-san]

Ah, you closed the pull. I force-pushed in the same branch, so if it was left open, it would show you the new commit. Anyway, here.