Match These Tags

[Ding, Zhao Chen(diydiy)]

There are many instances where you need to "tie" two or more actors together in some way. The Unreal Engine does this by using tag properties. These are name variables. It doesn't matter what the actual value is, the important thing is that they match.

The classic example is the Events → Tag and Events → Trigger pair. If we have:

* A Trigger actor with Events → Event = foo
* Another actor with Events → Tag = foo

then the two are tied together, and the Trigger will activate the other actor. It doesn't matter that we used "foo", only that they both have "foo". We could have used "bar". But of course, if later on we want to match another, different pair, then we can't use "foo", because it's already used. We can give many other actors the "foo" tag, but they'll be involved with the two we already have: other Triggers, or other actors we want to be activated by any of the triggers (database people will recognize this as a many-to-many relationship).

For example, the Trigger actor could activate a roomfull of monsters, like this:

* Trigger actor with Events → Event = foo
* Monster1 with Events → Tag = foo
* Monster2 with Events → Tag = foo
* ... and so on.

All the monsters will be activated by the Trigger.

Many other properties use this concept. For example: FortStandard → NearestPathNodeTag, etc