How the hell did they do it?

[Borg]

Community chest 4. Map21. Location -491,-3386. Loaded in DB2, Zdoom (doom in doom). Doom2 resource.

They have several platforms forming a path to another area. In visual mode you can see all the textures used. Nothing is flagged hidden in linedefs yet when you run it all the textures are transparent except 1 mid texture that forms a frame. This mid texture is lower pegged and I'm not able to see it in visual mode, only run/test. It shows up in sidedefs though. I could not duplicate the situation. There is a linedef action involved that I don't understand. 213 Floor change brightness to this brightness. This line is in another area and is tagged the same as the sector where the textures are transparent.

Maybe there is somebody bored enough to explain what is happening here.

[Gez]

What you are missing are lines #7913 and #7915. They're in a control sector a short distance to west of the area that puzzles you. They use line type 242: Transfer Heights. That means that while the sectors are at their normal height as far as gameplay is concerned (collision, movement, etc.), for the renderer however, the sector height will be that of the Transfer Heights' control sector (#727 in this case) instead of the real height. This is how the real platforms are hidden, and instead it's the midtextures which lets the player "see" the platforms.

[Borg]

You nailed it. Damn you guys really know this stuff. My linedef action 242 actually reads Create fake ceiling and floor, but it apparently does the same thing as Transfer Heights. All I did was set the control sector floor and ceiling heights the same as the surrounding sector where the platforms are as in Cchest4. I looked pretty hard for a control sector in Cchest4 and never saw it. I only saw that other line action which I still don't understand.

Thanks. I have a new toy. You have unleashed a monster.