Project Specific Part of Scene Capture


I recently watched this video by Sebastian Lague explaining how he made portals in Unity. I was trying to make a similar version in Unreal using C++, and so far I have been able to follow along. However, I can’t think of how to replicate what he is doing at 3:10.

It is kind of hard to explain, but basically the SceneCaptureComponent that takes a picture of the view from the other portal is projecting its entire view on to the first portal. The intended effect is that the other portal acts as a window and only the view from that window is projected onto the first portal.

How can I first determine what part of the capture represents that window and then how would I only project that part. Thanks in advance.