I've been testing a few games on ROBLOX, trying to find a game I once saw. It was a door that the player could see through, but ONLY if the player was looking straight through the door. I've done a picture to show you how it worked like: http://prntscr.com/9j141p The player could also walk through this door thus he could see the rest of the map. Now I've been wondering how this was done. I'd really much appreciate any methods or code lines that might help.
Raycasting to detect parts that are in front and making those visible in a local script with filtering enabled. You could also check cells in front of you with FindPartsInRegion3 and only make those parts visible.