Shown here are a table (A) and cabinet (B) knocked over for cover. Initially the small border in the door opening (C) did not exist. When it was added, we discovered that the player could not easily jump over the cabinet, since his head would be stopped by the border! Rather than make the ceiling higher (a major hassle), we made the border a world model that was solid to all but the player. It would stop shots, but the player could jump through it. The border is small enough so a player will not notice his head passing through it when jumping over the cabinet.