Linedef type 140, Intangible from Bottom, Opaque, is a type of floor over floor platform which can be jumped through and onto from below, but is solid to anything landing on it from above. It is useful for making vertical one-way routes, or for creating platforms which are easier to access. It is also useful in 2D mode for creating platforms reminiscent of classic side-scrolling tangibility physics.
Setup
The flats, floor height, and ceiling height of the FOF are determined by the flats, floor height, and ceiling height of the control sector, and the sidedefs of the FOF's walls are determined by the sidedef of the control linedef.
The light level of the control sector will determine the brightness of the shadow cast by the FOF. If the light level of the control sector is lower than that of the target sector, then it will cast a dark shadow. If the light level of the control sector is higher than that of the target sector, then the FOF will illuminate the area below it. If the light level of the control sector is equal to that of the target sector, then the FOF will not affect the light of the area below it.
If Flag [6] / Not Climbable is checked, this FOF will not cast a shadow.