Talk:MAP05: Ghost Town (The Plutonia Experiment)



Not even a single mention about those crazy scrollers of Sector 57? (the niches where the Chaingunners await you after killing the Spider). I don't recall seeing them on any other level, and the editor just says that its a normal scrolling wall. This weird effect can only be seen on Vanilla Final Doom (1.9 and Anthology version IWADs) and Chocolate Doom. Other modern ports seem to interpret them as normal scrollers and not a crazed up bizarre wall efect. hfc2X 00:50, October 18, 2010 (UTC)

So what's actually going on with those? I've found this old post by Kaiser but it does not exactly make sense to me. All those linedefs and sidedefs have perfectly different indices. Unmaker 17:14, 1 October 2013 (UTC)
The actions cumulate. All 24 linedefs share sidedef #327. Since they all have the scrolling type, the walls scroll with a 24-tuple speed. I think that is what Kaiser meant, but the wording was misleading. --Jartapran 21:01, 1 October 2013 (UTC)
It was just me. I got confused because the Doombuilder apparently decompresses sidedefs. I have no idea if it can be turned off. Now I wonder however, was this design quirk deliberate or simply an unintentional result of sidedef compression?
SV's explanation itself is perfectly sound, and it's rather evident from the source too. As I understand it, this piece of code runs for every line in question every gametic, essentially scrolling the same sidedef every time (from p_spec.c):
   for (i = 0; i < numlinespecials; i++)
       line = linespeciallist[i];
       case 48:
           sides[line->sidenum[0]].textureoffset += FRACUNIT;
Unmaker 22:14, 1 October 2013 (UTC)
I would hesitate to describe it as intentional *in the engine*, as id's maps never compressed sidedefs. They weren't aware of the effect. Carmack would probably have considered multiple linedefs referencing the same sidedef to constitute a malformed map. None of the code in the engine tries to compensate for the possibility, this being one mere notable example (switch textures being another such). It just happens because the code above implicitly assumes scrolling lines have unique sidedefs. Now, as to whether or not it is intentional in this map's design, I can't say. You'd need to ask the original author I think. --Quasar 13:03, 2 October 2013 (UTC)