Talk:Wallrunning

ZDoom Wiki says this only works with north-south walls. Can this be confirmed in the source code? (i.e. IMHO trial and error may not be convincing, since it's so hard to do in the first place) Ryan W 04:05, 24 Jun 2005 (UTC)
 * It only does work with north-south walls. Not sure if it is that "rarely" used in demos, btw; from the top of my head, it's used in demos for Doom E1M8, E2M3 and E2M5, and Doom II MAP01, MAP20, and MAP31. - Fredrik 10:18, 24 Jun 2005 (UTC)
 * Ach, I knew I wasn't really cool enough to give people advice! :>


 * I do remember seeing this used e.g. on TNT 31, now that you mention it. I guess there's a fairly strong case to be made for it in a linear, squarish map like MAP01 or MAP31, where every tenth of a second can be important. To be perfectly honest, however, I have yet to figure out what really separates a 12:09 run from an 11:36 run in a big map --- is it mostly the RNG, an improvement in footwork, a new trick, or things like spinning macros and wallrunning which decrease the duration a few tenths of a second here and there?


 * I stand by the deathmatch part of the statement, though. It seems like [a] 90% of the time the map is some PWAD which is highly symmetrical, so nobody ever knows which way is north anyway, and [b] that slight hitch before the acceleration starts, especially when straferunning, can be enough of a delay to get one's head taken off. Ryan W 01:58, 25 Jun 2005 (UTC)


 * Addendum: I just did it with an east-west wall &mdash; want to see a demo? Ryan W 07:20, 25 Sep 2005 (UTC)


 * I'd definitely want to see a demo of this. Janizdreg 14:38, 25 Sep 2005 (UTC)


 * Wallrunning can also be achieved on double sided & impassable west-east linedefs (see this wad). And BTW, isn't the correct regular wallrunning direction south-north, not north-south? Janizdreg 14:38, 25 Sep 2005 (UTC)


 * You seem to be suggesting that I've been imprecise. Stunning!   :>
 * I'll try again. The demo I added to this article was south-north.  [[Media:e3m6wrb.lmp|This demo]] (file info) is west-east.  I'm not sure about other directions (but will fire up E2M3 of DARKHELL.WAD to try some at my earliest opportunity).
 * Obviously, if someone did extract a straight answer from the source code, that would be the ideal case. I myself don't know enough C to do so, alas.    Ryan W 05:34, 26 Sep 2005 (UTC)


 * Interesting - I didn't know you could wallrun on regular west-east walls too. It seems to be harder to pull off than on south-north or double sided west-east linedefs though. Janizdreg 17:38, 28 Sep 2005 (UTC)


 * Here's a quote from Adam Hegyi: "On one-sided linedefs it is south->north. On two-sided linedefs it is south->north and west->east. It's also possible to do west->east wallruns on one-sided linedefs. Seems to work rarely." I think we should rewrite the article according to this. Janizdreg 19:10, 28 Sep 2005 (UTC)


 * Yeah, probably. :>    I may have been able to make it work with sidedef 63 of MAP09: The Pit, but I didn't find the evidence conclusive.   Ryan W 20:32, 30 Sep 2005 (UTC)


 * Hmmmm-mm-m, and one also hears about things like this. I have no idea what could be going on there.   Ryan W 22:20, 3 Oct 2005 (UTC)
 * Wallrunning can also be executed on "walls" made of things. The usual wallrunning directions seem to apply to thingrunning too. I have no idea about the flying stuff mentioned on that page though. Janizdreg 19:12, 5 Oct 2005 (UTC)


 * Update: wallrunning also works &mdash; sort of &mdash; on sidedef 110 of MAP18: The Courtyard. I forget where I read about that, but [[Media:d218wrb.lmp|here is a demo of it]] (file info).
 * I'm a bit confused now. I'll have to think some more before I'm sure how to update the article (or perhaps someone less confused will do it instead).   :>     Ryan W 01:10, 5 Oct 2005 (UTC)
 * Further update: I changed the article to include the information in this discussion. I hedged a little bit on the MAP18 reference, for reasons that I hope are obvious in the demo &mdash; if that wall were 10 times as long, it would contain 10 times as many snags, and I'm not sure that would do a lot for my confidence in a deathmatch game.    Ryan W 11:27, 10 Oct 2005 (UTC)

Faster or slower than straferunning?
Does anyone know if wallrunning is faster or slower than straferunning (SR40 and/or SR50)? radius 06:10, 5 Jul 2005 (UTC)
 * Faster. Fraggle 08:41, 5 Jul 2005 (UTC)

"Parallel to the wall" is incorrect!
[[Media:rcktmiss.lmp|This demo]] (file info), though recorded as part of a different discussion, shows that wallrunning actually occurs at a slight angle to north-south walls. The rocket is fired in the same direction as the wallrunning, but is clearly closer to the wall at the north end than at the south end. Ryan W 23:43, 26 January 2006 (UTC)

Technical Explanation?
Is there some sort of explanation on why this bug happens? Why does it make you go faster? Why only North-South? Where's the code involved, and what could be changed to fix it? It seems odd that such an interesting bug is left unexplained in this article.


 * It's not odd, because this is a wiki, which means most things are unfinished. Believe me, our technical articles have come a long way.  When I first arrived, there were almost no code excerpts anywhere.


 * To attempt to answer your question, I think this is still an unsolved problem. It is generally believed that wallrunning is related to roundoff error in computing the player's location, which somehow creates large glitches in momentum when the engine believes that the player is moving into a wall, but the exact details have not been explained.  Although, see the remark by Graf Zahl here.    Ryan W 07:52, 7 December 2007 (UTC)


 * Actually, that's a pretty good explanation. I can sort of understand from that why it only goes N/S then, because I'm pretty sure one is checked before the other. -Wagi 69.51.157.227 15:10, 17 January 2008 (UTC)


 * I'm not entirely satisfied. Looking at the function in question, the bug should only occur when the player is moving North or East, but our article claims a speedrunner can also take advantage of the bug while moving South. The explanation given by Randy Heit also does not indicate why the bug only happens sometimes on specific walls, and not on just any wall. Zack 19:54, 17 January 2008 (UTC)