I want to make a warp area that looks like it leads to another room, but the room is in a different area in the map. You know how it looks when looking through a portal right? It looks connected, but it's really a portal. Something similar to that without a blue or orange rim.

https://developer.valvesoftware.com/wik ... ortal_door

Be careful using these, it's easy to make your map start making no sense, and hard to use cleverly. You definitely should not be using these as transitions for rooms if there are any other options available.

Personally I use them to link angled rooms rather than rotating a ton of brushes that will shit bricks on compile, but theres also ways around that with good instance usage (I'm just noob )