OpenGL cube map using not static texture

Question

What i am trying to understand how to do is lets say we have an interactive application ( game, similation etc. ). Now instead of using a image loaded from memory to texture the sides of a cube, how do i instead use the rendered content taken from that direction and instead use it as a texture.

So imagine a camera being placed inside the cube pointing towards the +z direction. The side immediatly infront of the camera would be textured with an image of what exists infront of the camera. The top side of the cube would be textured with an image of what exists above the camera. etc.

Hope this is clear.

Thanks

Answer 1

That's called render to texture, and in OpenGL it is achieved using Framebuffer Objects (FBOs).

Answer 2

On OpenGL implementations that don't support EXT_framebuffer_object you can render into a subset of the primary framebuffer using glViewport() and then copy that image into a texture via glCopyTexSubImage2D().