183:Line_AlignCeiling (lineid, side)
- lineid: Line to use for alignment
- side: Align sector in front of or behind the line?
Causes the tops of the ceiling textures in the front (0) or back (1) of the specified line to align with the line. Any future scrolling or rotation of the ceiling will use this new alignment as a basis, unless changed again with one of these specials.
Note that this is not a static init linedef type, but one that has to be explicitly activated, either by a switch, a walkover trigger, a script, etc. Just putting it on the line will not do anything. You must first assign a line identification number to the linedef to which you want the flat aligned, then use the activator. If you want the flat aligned right from the start of the map, use the special in an OPEN script.