Give portal some perceptual knowledge

In the figure, the purple patch is the portal inserted into the wall in the correct position. It connects an indoor area and an outdoor area.

The white line in the figure indicates the new video cone formed after the video cone of the Central Camera is cut down by the portal. The new video cone is much smaller than the original video cone and is used to cut down the objects and portals in the connected areas behind the portal.

This is a portal that is removed from the correct location for clarity.

This is the new video cone formed after the camera cone is cut by the portal.

This is where only the portal is visible on the camera.

This is the new video cone after the camera cone of the local portal is removed by the portal.