Showing a different place outside a window?

Hi, guys. I don't even know how to google this.

We're developing a game that requires a room to have three windows and show a different environment on each of them.

For example, one window should show a beach, another one a forest and the other one a city.

How can I do this?

Thanks!

 

Their called portals, they are made with RenderTexture, extra cameras and some complex math to get the viewing angles right. Lucky for you, there's an asset for that:
https://www.assetstore.unity3d.com/en/#!/content/45383
Edit: Here's a free solution: http://algoholic.eu/unity3d-indie-free-portal-effect-project-sources/

 

Yes, I thought about render textures and rotating/moving the camera, but that's just too complex for me. Thanks for the free solution! I'll check it out.