Floor Cucking or Surface Cucking (a.k.a. Floor Overshadowing) is a phenomenon that occurs when 2 floors or 2 ceilings (both need not be floors, despite the name) are prioritized unintuitively. Triangles are prioritized by the height of their first vertex. This means that, for example, 2 floors can overlap each other, with the first being on average much higher than the second; however, if the first vertex of the second floor is higher than the first vertex of the first floor, the game will decide that the second floor is higher.