zdoom sky scrolling like a flat

I was wondering how are done
the zdoom skies like the one in torment
and torture 2.Seems to be warping applied to a texture + flat moving (not talking about thunder)...
I only know the MAPINFO stuff to make a basic scrolling sky and want to do a better one =).Please help.

http://www.zdoom.org/wiki

may help.

It's done with a skybox that has a warping texture for a ceiling (FWATER1 in TNT2's case) and line_horizen lines to make it so you don't end up with a room for a sky. The a scroll ceiling deal is done and that should do it.

That's the basic idea of it, and all of these things can be found in the ZDoom Wiki. If you are still stuck, you can always load up the map in an editor and see how it's done.

thanks chopkinsca for the skybox tip, I have a better sky now, the only thing I can't find is how to set a line_horizon;
I searched in wiki and zdoom reference ,but only found the definition of it (in wiki)

You just have to put the line_horizon special on the line where you want to have the horizon. The rest happens automatically.

In case you're unable to figure out what linedef type Line_Horizon is, it's type 9.

hey thanks nightmare, that's working great.I bet this trick can deserve a lot
of stunnings effects.BTW do you know Fragmare?He is from the doom community ,and ,a long time ago, he said to know you.