Hi everyone,
I’d like to make a blueprint (or maybe if there’s another way), where the boundaries are a box,
and any actor within that box, is not rendered.
Is this possible?
You can do this by creating a blueprint with a Box Collision Component. The Box component will have ‘On Component Begin Overlap’ and ‘On Component End Overlap’ events. Just use these to set the visibility of whichever actor is overlapping the box. The ‘Set Actor Hidden in Game’ node works.
If you want you can cast the Other Actor variable to a certain type (if you only want characters to go invisible for example).
Right, but unfortunately this turns the whole actor to not render.
I only want the part of the actor within the box.
Ive been wondering about this also. I think it might be done in the material editor with some kind of blend. Or maybe cast a mask in world space and have it affect the actor only when he is at that location. Haven’t figured it out yet. Hopefully we will find a solution 
This might be helpful, this is a pretty cool way to do it with a material from Eat3D’s YouTube channel:
UE4 Shader FX: Volume Vertex Collapse
Might need some tweaking for what you want, but it should get you started.
For anyone else finding this thread…
The answer is in this video by Epic
Which video did you refer to? The original one in your post in unfortunately set to private. Any idea if there is a reupload or something in that direction?