Editing Talk:Engine bug (section) From DoomWiki.org Warning: You are not logged in. Your IP address will be recorded in this page's edit history. Anti-spam check. Do not fill this in! == Bugs not in this list == I think the following two things are not yet listed in this article, but I don't quite understand what they're referring to, so I can't tell. [http://prboom.sourceforge.net/mbf-bugs.html Look at <s>"Fast and respawn options not reloaded from savegames correctly" and</s> "DR doors corrupt other actions".] Also, I keep hearing rumors that there are bugs in the vanilla stair-building algorithm (e.g. people "optimize" the algorithm while writing source ports and then TNT 30 demos don't work because of that weird circular staircase), and even incompatibilities across vanilla versions, but I can't find any technical details about it. Can anyone confirm this? [[User:Ryan W|Ryan W]] 00:35, 21 Jun 2005 (UTC) : Yes, I think there are two separate compatibility issues with stairs. One concerns how '''multiple stairs are started from a single switch'''. MBF and PrBoom implemented it incorrectly, apparently failing to generate some of multiple staircases. : However, the TNT30 issue is another one. (It doesn't even have multiple staircases generated from a single switch.) The problem is that the original Doom code occasionally '''increments the step level of a staircase twice''' (maybe even more) while trying to find the next step to rise. TNT30 compensates this behaviour with a kind of duct tape fix: when it builds 24 unit high steps using the 8 unit action, it only has two stair sectors where a correctly behaving engine would need three. Original Doom acts incorrectly and builds 24 unit steps. A fixed engine (such as Doom Legacy) only makes them 16 high. As a result, the red key stairs become too low. So do the crucial stairs of the boss room. Ultimately the level cannot be completed (using the intended route, at least) if the engine has been fixed. : It becomes even more confusing because the same comp_stairs option of various ports may try to handle both of these bugs. To skip the messy parts (mostly concerning MBF), any good post-2001 port should have a comp_stairs option which makes stairs work precisely like in Doom. : It's a long story. I can try to explain it in detail, even though some parts of it are still hazy to me as well. If someone is interested, I'll create an account and discuss it somewhere...a bit later. Drop a line here or something. {{unsigned|195.148.54.26}} Does anyone know why floor textures near doors sometimes appear to slide back and forth as the door opens and closes? [[Media:E1m4slid.lmp|Here is a demo of it]] ([[:Image:E1m4slid.lmp|file info]]; the effect is much more obvious in PrBoom 640x400 than in Doom95 or vanilla). : Rounding errors in the BSP builder and the rendering engine. While the effect doesn't entirely disappear, it does become a lot less noticable on that level if you rebuild the BSP nodes. [[User:Fraggle|Fraggle]] 21:57, 3 March 2006 (UTC) :: I tried this with DeePsea (i.e. Zennode), but it didn't seem to change anything. [[User:Ryan W|Ryan W]] 16:33, 9 March 2006 (UTC) ::: Addendum: I think wall textures can do something very similar. For instance, near the yellow key on E1M7, there is a shimmering effect on the technical walls as you move around: sometimes the narrow white strip is exactly on the corner, and sometimes it isn't, depending on where the renderer has rounded off the sidedef's length. [[User:Ryan W|Ryan W]] 20:21, 26 January 2007 (UTC) :::: Further addendum: this post to the PrBoom listserv shows that I'm not just imagining the wall texture part. [[User:Ryan W|Ryan W]] 21:00, 17 June 2008 (UTC) <pre> >Author: entryway >Date: Sun Jun 8 15:32:55 2008 >New Revision: 2766 > >Modified: > branches/prboom-plus-24/prboom2/src/r_main.c > branches/prboom-plus-24/prboom2/src/r_main.h > branches/prboom-plus-24/prboom2/src/r_plane.c > >Log: >Fix vanilla unprecise calculation (vibrations) of the texture >coordinates for flats in software renderer. Visplanes with the same >texture now match up far better than before. You can see this bug on >cchest2.wad\map02 in room with moving illumination around the room >with sector 265. The new algo is ~1% slower than the original and >will use only if render_precise is 1. </pre> One more big one: the general roundoff error when the engine tries to compute the location of an object. For example, monsters stuck in walls after being resurrected by an arch-vile, or [http://games.moria.org.uk/doom/research/running-body here] where Phipps says, "But if the DM starts are considered too close to the walls, how can the players move when they are first spawned?" [[User:Ryan W|Ryan W]] 01:43, 31 May 2006 (UTC) Vanilla Doom does not support Sprite/Flat PWADs. That's a real nasty issue that should be listed since it is an EXE bug. : Good point. But wasn't that fixed in v1.9? [[User:Ryan W|Ryan W]] 19:02, 29 October 2006 (UTC) : Hmm, apparently not. [https://www.doomworld.com/vb/showthread.php?s=8082b865e668facf8df0099ad8e4f414&threadid=40548 Here] is some recent discussion, including a hack you can do with a WAD editor to circumvent the problem. [[User:Ryan W|Ryan W]] 05:19, 11 July 2007 (UTC) A few more possible entries, mostly from the ZDoom and PrBoom changelogs: * Bizarre foreshortening of column sprites when viewed from a sector whose floor height is significantly above their base (e.g. the normal exit of E1M3). * Frame skipping during screen melt (easy to see in most UV speed demos of E1M1; also happens with weapon changes). * <s>The same phenomenon that causes [[Mancubus fireball clipping]] sometimes allows you to grab objects through walls.</s> * Memory "wastage" (?) by Z_FreeTags. * Monsters sometimes retaliate against wrong character in multiplayer mode. * Top of pistol sprite shown at bottom of screen. * Unused player death sound in Registered/Ultimate Doom. * Deleted thinkers referenced by monster targets, tracers, or soundtargets. * Voodoo dolls move along with player. * SSG neck not lit up correctly when SSG is fired in a dark room. * SSG shows reload frame while firing frame is still displayed. * <s>"Raise to shortest texture" always fills in AASHITTY.</s> * Flickering light not remembered across savegames. * MAP30 telefrag "inconsistency". (Not sure what this means -- is this just the standard MAP30 exception?) * <s>Pain Elementals can spawn Lost Souls through monster-blocking linedefs.</s> * Live monsters can't be pushed off ledges. [[User:Ryan W|Ryan W]] 02:47, 4 November 2006 (UTC) * Saving a game and then re-loading causes all enemies that were not in-line-of-sight with the player to be "asleep" when the load resumes. * Punching the fist in the air, which causes no sound whatsoever, causes enemies around to wake-up the same as if a sound had been generated. {{Unsigned|86.164.5.145}} :: First item is [[Monster targets not preserved in saved games|already in the list]]. Second item has been discussed [[Talk:Monsters#Arousal: loose end|here]], but apparently not everyone agrees that it is a bug. [[User:Ryan W|Ryan W]] 16:35, 6 April 2008 (UTC) <s>There was a bug in v1.0 (I think) where there were really only four save slots, but it looked like there were six. Slots 4 and 5 always looked blank, but if you tried to use them, it would instead save in slot 0 or 1 respectively, overwriting whatever was there. Setting up a white box to verify this would be a bit painful at the moment, so I'm posting here in case someone else can do it easily. [[User:Ryan W|Ryan W]] 19:04, 6 December 2006 (UTC)</s> Two additional and rather obscure LOS problems are described [https://groups.google.com/group/rec.games.computer.doom.editing/msg/1411b573f2b481da?hl=en& here]. The first one ''might'' be [[Hitscan attacks hit invisible barriers in large open areas]]. [[User:Ryan W|Ryan W]] 10:20, 22 January 2007 (UTC) This [[E1M7: Computer Station (Doom)#Bugs|chaingun sprite clipping problem]] is in fact quite general — on any level with a lot of zombies, it's pretty easy to get corpses and/or dropped weapons to appear on the wrong side of a door or curb — but I do not know whether this is already included in one of the phenomena we have listed here. [[Sprites flickering across ledges or lifts]], possibly? [[User:Ryan W|Ryan W]] 00:15, 27 January 2007 (UTC) [https://sourceforge.net/tracker/?func=detail&atid=103396&aid=1661112&group_id=3396 This rendering anomaly] may or may not be the same as [[Sprites flickering across ledges or lifts]]. I can't tell, so I'm listing it here. [[User:Ryan W|Ryan W]] 21:41, 21 February 2007 (UTC) On E1M3, when I look out of the inviso room to the south, why can I see the sky through the top edge of the grate texture? It's as though there's a horizontal slime trail, though I've never heard of that. I think that it isn't tutti-frutti: when I "zoetrope" by walk backing and forth a bit, the mountain is clearly there. (Or is this simply what happens ''instead'' of the day-glo colors when a middle texture has undefined pixels on a 2S wall?) [[User:Ryan W|Ryan W]] 07:05, 2 March 2007 (UTC) : Addendum: this also happens when walking toward the yellow key on E1M9 (if you're close enough, you can see the flashing lights through the "solid" boundary between the grate and the floor). [[User:Ryan W|Ryan W]] 14:53, 14 April 2008 (UTC) <s>In {{competnftp|doom/speed/ep1-2537.zip|ep1-2537.zip}}, around the 19:40 mark, the player fires a rocket into a solid wall (supercharger courtyard on E1M6). It hits the wall and ''disappears without exploding''. Huh? [[User:Ryan W|Ryan W]] 10:46, 4 March 2007 (UTC)</s> : Be nice if I had actually linked to the article that explained this! It is [[Bullet puffs do not appear in outdoor areas|here]]. [[User:Ryan W|Ryan W]] 16:58, 27 December 2007 (UTC) <s>Also on E1M6, when I stand in sector 190, why on earth can't monsters in sector 145 see me? The interposing linedefs don't seem to be doing anything weird. [[User:Ryan W|Ryan W]] 14:31, 4 March 2007 (UTC) :The [[E1M6:_Central_Processing_%28Doom%29|Central Processing]] [[Reject]] is set true for sectors 145 <-> 190 --{{suppresswl|w:User:Splarka|Splarka}} <small>({{suppresswl|w:User_talk:Splarka|talk}})</small> 22:11, 4 March 2007 (UTC) ::Good heavens! I would never have thought to check for {{idgames|id=13017|title=that kind of lowbrow thing|linkonly=1}} in an id map. :> (Maybe I should rebuild all the tables and look for more, hmmm.) Thank you once again for helping to educate me. [[User:Ryan W|Ryan W]] 15:27, 5 March 2007 (UTC)</s> A few more from [[Doom change log]] (hopefully, somebody else recognizes these and can at least suggest a title): * "Sound problems" fixed in v1.4. * Are the SERSETUP changes in v1.5 considered a bug fix? * "Response file bug" fixed in v1.5. * "Bug when using a baud rate greater than 38,400 bps in null-modem/modem games" fixed in v1.5. [[User:Ryan W|Ryan W]] 01:07, 26 May 2007 (UTC) A thread on the Doomworld forums has just reminded me that objects can be grabbed through walls due to run-of-the-mill roundoff error (e.g. the armor bonuses behind the steel lift on MAP06), not just by mancubus fireball clipping. Or does that happen merely because the sprite is so much smaller than the object's radius — it ''looks'' right to put it that close to the wall, but it really isn't? [[User:Ryan W|Ryan W]] 06:19, 11 July 2007 (UTC) Weapon stays fixed at last bobbing position when firing continuously. {{Unsigned|Zom-B}} A possible bug with the intermission screens is described [https://www.doomworld.com/vb/post/612873 here]. We all know it doesn't work quite right in Doom95, but the way Fraggle describes it, the DOS version of Ultimate Doom (for instance) should also be affected. [[User:Ryan W|Ryan W]] 04:26, 17 September 2007 (UTC) :That is a bug that existed in an older version of Chocolate Doom. Vanilla Doom's source contains the correct code. [[User:Zaximus|Zack]] 04:41, 25 December 2007 (UTC) <s>More static limits which might or might not be intrusive enough to be considered bugs: MAXLINEANIMS, MAXOPENINGS, MAXBUTTONS, MAXSLIDEDOORS, MAXEVENTS, MAXANIMS, MAXCEILINGS, MAXSWITCHES. [http://prboom-plus.sourceforge.net/doom-plus.features.html] [https://www.doomworld.com/vb/source-ports/36097-doom2-v1-92-no-more-visplanes-and-drawsegs-overflows/2/] [http://forums.newdoom.com/showthread.php?p=423851#post423851] Hmmmm-m, I thought the linedef specials limit was a Boom issue, not a vanilla issue. [[User:Ryan W|Ryan W]] 18:52, 26 January 2008 (UTC) ::: Oh yeah; as a recent post on the PrBoom listserv reminds me, there is also a static limit of 100 on the number of WADs/DEHs/etc. that can be loaded at once. Is it called MAXARGVS or MAXWADFILES? [[User:Ryan W|Ryan W]] 17:27, 1 June 2008 (UTC)</s> Now included in the [[Static limits]] article. [[User:Ryan W|Ryan W]] 04:14, 25 February 2013 (UTC) * "why is it that if you give a non-flying monster the lost soul attack, sometimes it starts bouncing up and down strangely?" * "the bizarre map24 trick, where the player is able to make use of a narrow ledge that is the other side of an impassable linedef." * "[Invalid values of sector type] cause an error and exit to DOS. This includes these two values which were developed and are quoted by id as being available, but are not actually implemented in DOOM.EXE (as of version 1.666): 6 06 - crushing ceiling, 15 0f - ammo creator" [https://www.doomworld.com/vb/doom-general/22459-ideas-wanted-technical-aspects-of-the-doom-engine/] [https://www.doomworld.com/vb/doom-general/22459-ideas-wanted-technical-aspects-of-the-doom-engine/2/] [[User:Ryan W|Ryan W]] 19:20, 26 January 2008 (UTC) This bug in rendering logic [https://sourceforge.net/mailarchive/forum.php?thread_name=20081018122439.13257.qmail%40mail.lirrebit.de&forum_name=prboom-notes] <i>seems</i> to be present in the original source release (r_things.c), but I don't know anything about pointer arithmetic, so I'm not certain enough to create a stub about it. Could it actually cause a crash, for example? [[User:Ryan W|Ryan W]] 21:46, 20 October 2008 (UTC) According to [[James Haley (Quasar)|a reliable source]], a monster is immune to hitscan attacks that don't cross its diagonal [https://www.doomworld.com/vb/post/742367]. (!) [[User:Ryan W|Ryan W]] 18:28, 11 November 2008 (UTC) Andrey Budko says: [https://sourceforge.net/mailarchive/forum.php?thread_name=20090108140430.4969.qmail%40mail.lirrebit.de&forum_name=prboom-notes] <pre> >+ // Do not exit if corresponding demo lump is not found. >+ // It makes sense for Plutonia and TNT IWADs, which have no DEMO4 lump, >+ // but DEMO4 should be in a demo cycle as real Plutonia and TNT have. >+ // >+ // Plutonia/Tnt executables exit with "W_GetNumForName: DEMO4 not found" >+ // message after playing of DEMO3, because DEMO4 is not present >+ // in the corresponding IWADs. </pre> Is this truly a bug in the original application, or is it something that can't really happen unless you try to run a mismatched IWAD + release version (trivial with the command line in PrBoom, but would require moving files from folder to folder in DOS, which is usually assumed to be unsafe)? [[User:Ryan W|Ryan W]] 00:27, 20 January 2009 (UTC) [https://www.doomworld.com/idgames/index.php?id=13975 "<nowiki>[A]</nowiki> peculiar bug in the Doom 1.666 engine which does not allow multiple sector tagging for raised floors."] [[User:Ryan W|Ryan W]] 00:58, February 5, 2010 (UTC) Donut linedef special can apparently fail depending on the map slot [https://www.doomworld.com/vb/post/828228]. [[User:Ryan W|Ryan W]] 01:01, June 10, 2010 (UTC) <s>Catastrophic memory corruption can occur with more than ~4000 lumps. [https://www.doomworld.com/vb/post/1010985] [[User:Ryan W|Ryan W]] 20:25, 24 September 2011 (UTC)</s> Whoops, didn't notice this had been added to the table. [[User:Ryan W|Ryan W]] 04:18, 25 February 2013 (UTC) From [https://web.archive.org/web/20170113202331/http://doomedsda.us/col159.html Retur_na.txt]: ''"And I now confirm the old v`.2 bug: recording is truly a [http://www.urbandictionary.com/define.php?term=PITA PITA] as your player keeps constantly getting pulled to a side."'' He does? [[User:Ryan W|Ryan W]] 15:12, 7 March 2012 (UTC) Recent dwforums thread focusing on Heretic glitches, most of which appear not to be in this list: [https://www.doomworld.com/vb/doom-general/69186-heretic-bugs-version-differences/]. [[User:Ryan W|Ryan W]] ([[User talk:Ryan W|talk]]) 16:42, 5 July 2014 (UTC) : Given that you feel this article's already too long I believe that Heretic and Hexen glitches should be started as new articles, as I did for [[Engine bugs in Strife]]. --[[User:Quasar|Quasar]] ([[User talk:Quasar|talk]]) 20:27, 5 July 2014 (UTC) Summary: All contributions to DoomWiki.org are considered to be released under the CC BY-SA 4.0 International (see Doom Wiki:Copyrights for details). By contributing, you agree to be bound by the Terms of Use. Your changes will be visible immediately. Please enter a summary of your changes above. Do not submit copyrighted images or text without permission! This includes text taken from in-game codices or logbooks, or from official instruction manuals, strategy guides, and other such books. This project is not affiliated with id Software, Raven Software, ZeniMax Media, Bethesda SoftWorks, or any other commercial software developer or publisher. 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