How to activate post process when character [not camera] overlaps volume?

[MostHost_LA]

Many, Tons, Thousands of different ways to go about this.
How you do it would depend almost 100% on your current post process setup.

For starters. the Easiest possible way, is on the Level Blueprint

Follow these steps exactly.

1. Create a cylinder (or a copy of your mesh that’s a round plate) this will be your Volume. It will be used the same as a trigger.
   In the properties you can select Hidden In Game to make it disappear.
   Deselect Cast Shadow to prevent the shadow from drawing.
   In the Collision section you need to check Enable Overlap Events, and set the collision type to Overlap All

2. Create a post process or take the one you have and check the Unbound checkbox.
   Make your PP Disabled (uncheck enabled).

3. Open level BP, Drag into it the Post Process and the Cylinder or copy of the base mesh used as volume.

4. From the Cylinder/Mesh/Volume drag off and type Bind Overlap
   You get 2 top entries, OnActorBeingOverlap and OnActorEndOvelrap. Create both nodes.

5. From the Overlap Nodes, drag off from the event pin, let go anywhere, expand Add Event, select Add Custom Event.
   Create 2 events, One for the PP_OverlapStart and one for the PP_OverlapEnd

6. From eitehr PP_OverlapStart or end, drag off from OtherActor , type Cast, and select the name that matches your main character.

7. Grab the PP node you dragged in on step 3, drag off from it and type Set Enabled - select the Last Boolean you find. Hook it up after the Cast. Check the checkbox to enable it.

8. Duplicate the Boolean hook it up to event end’s cast, uncheck the checkbox to disable it.

9. $$$ ?

Here is what the BP looks like:

The effect in action:

Gyazo

A screenshot of where the Cylinder is. PP Is near the cube so you know it’s not being overlapped.

BONUS POINTS:
If you create a custom PP material and assign it to the post process, you can actually hook up a Material Parameter Collection and lerp the value with a timeline to Enable/Disable the PP effect.
Just make sure that Enable/Disabled is delayed until after the TimeLine ends.

PP Material Example:

BP Code Update:

Timeline:

End Result:

Gyazo