Ah, so you do viewportal blending aswell. Nice.
Yesterday, after trying your demo i searched the web for Portal/view blending. Someone did it with a depthmap, but your color approach seems much "simpler".

You mentioned a HDR pipeline. What/How does it help in this case?

Idea: For your portal, i had an idea yesterday. For moving objects through. I thought, by deforming the collision shape of an object with stands on a floor portal for example, it should move thorugh the Portal(visually, a clone does the same on the other side).

HELP, iam thinking in portals

PS: For the stuttering: stay in front of the box, look directly into it(but stand in front and not in it). Now strafe left/right. rotate the cam a bit if desired. And when passing the corners(from your mainview perspective), it seems to stutter, while you're in the same room.

EDIT: So the stuttering doesnt appear when walking through the protal, but in the startroom.


Greetings
Rackscha