Able Ability System Info and Support Thread

[ExtraLifeMatt]

@mikecoker

@ Hi , I wanted to alert you to another problem we’ve encountered with Passives. If you have a passive ability that uses PlayAbility to spawn a couple more passives on the same actor, there is a crash (exception in editor) that can occur. If you look in the TickComponent code where you update Passives, you’re using this loop with an iterator:

for (UAblAbilityInstance* Passive : m_PassiveAbilityInstances)

If any of the InternalUpdateAbility(Passive,…) calls spawn new passives (like in the case above) then the m_PassiveAbilityInstance array will be modified. We’ve had a few crashes when this happens so I changed the code to do a reverse iteration like so:

for (int idx=m_PassiveAbilityInstances.Num()-1; idx >= 0; idx–)

This should allow for removals and additions (though adds will be skipped in the current iteration) without throwing any exceptions. You may choose to solve it a different way, but I wanted to let you know there was a problem.

Thanks,
Mike

Hey Mike.

That change makes sense. The only problem I see is if you do a reverse iteration, your new passives may not be updated (which may or may not be intended) that frame, which may or may not be fine.

I’m slightly shocked you were able to modify that passive in place, they should be queued up to be applied the next frame. How are you applying the passives? Just calling ActivateAbility?