is this just in general or do you have specific things you want to know are in view port?
Example if your looking for a bool is such and such in view port that I don’t know about but you can track a few objects. Keep in mind this requires tracking a objects location every frame.
So if you have kb object no big deal it’s basically like a radar…
You can dot prod the actor location to your forward vector and find the angle is positive. And also check if length is in range this does mean you see it through walls of course. And additional line trace if that is true would need to be done to know if it’s actually visable.
But it’s only heavy on computation if your trying to get a ton of actors information.
Explain more and I’ll try and see if I have a solution.