Scene regions can trigger an event when the actor enters/leaves it. Just attach a script to the region (in SceneEdit) containg something like:
on "ActorEntry"
{
// some action when actors enters this region
}
on "ActorLeave"
{
// some action when actors leaves this region
}
As for the collision between actors/entites... you are probably already familiar with scene blocked regions and waypoints. So, the actors/entities can have their own blocked region and waypoint set, which moves together with them. All you need to do is to add something like this to your actor/entity definition file:
BLOCKED_REGION {
POINT {-60,-48}
POINT {46,-48}
POINT {46,53}
POINT {-60,53}
}
WAYPOINTS {
POINT {-65,-53}
POINT {-56,39}
POINT {51,-58}
POINT {60,58}
}
There is currently no tool for interactively defining those values, because 1) this feature is rarely used 2) you can use the definition above without modifications