Difference between revisions of "Engine bug"
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** The Doom engine includes few safeguards against [[Wikipedia:Arithmetic overflow|''overflow'' conditions]]. | ** The Doom engine includes few safeguards against [[Wikipedia:Arithmetic overflow|''overflow'' conditions]]. | ||
** Line-of-sight calculations, [[Doom rendering engine|rendering]] algorithms, and the [[Doom rendering engine#Node building|BSP tree]] are also susceptible to [[Wikipedia:Floating point#Accuracy problems|''roundoff'' errors]]. | ** Line-of-sight calculations, [[Doom rendering engine|rendering]] algorithms, and the [[Doom rendering engine#Node building|BSP tree]] are also susceptible to [[Wikipedia:Floating point#Accuracy problems|''roundoff'' errors]]. | ||
− | ** The engine imposes a number of ''static limits'' on [[Thing]] placement and map construction, which sometimes fix one problem by creating another. | + | ** The engine imposes a number of ''[[static limits]]'' on [[Thing]] placement and map construction, which sometimes fix one problem by creating another. |
* '''Fatal''' bugs are those where the engine crashes (often with the [[Venetian blind crash|Venetian blind]] effect) or else exits the game in a controlled fashion, usually with an [[error message]]. '''Y*''' means that termination is possible, but not inevitable. '''N*''' means that the program keeps running, but that rendering or character behavior may be sufficiently compromised that meaningful gameplay becomes impossible. | * '''Fatal''' bugs are those where the engine crashes (often with the [[Venetian blind crash|Venetian blind]] effect) or else exits the game in a controlled fashion, usually with an [[error message]]. '''Y*''' means that termination is possible, but not inevitable. '''N*''' means that the program keeps running, but that rendering or character behavior may be sufficiently compromised that meaningful gameplay becomes impossible. | ||
Line 41: | Line 41: | ||
! N | ! N | ||
! Y | ! Y | ||
+ | |- | ||
+ | | [[1% damage bug]] | ||
+ | | | ||
+ | | Algorithm | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | |- | ||
+ | | [[Absurd texture name in error message]] | ||
+ | | Undisputed | ||
+ | | Algorithm | ||
+ | ! Y* | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
|- | |- | ||
| [[AASTINKY|AASTINKY and AASHITTY]] | | [[AASTINKY|AASTINKY and AASHITTY]] | ||
Line 54: | Line 70: | ||
| Overflow | | Overflow | ||
! N* | ! N* | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | |- | ||
+ | | [[Anomalous angry face behavior]] | ||
+ | | | ||
+ | | Algorithm | ||
+ | ! N | ||
! N | ! N | ||
! N | ! N | ||
Line 59: | Line 83: | ||
|- | |- | ||
| [[Arch-Vile fire spawned at the wrong location]] | | [[Arch-Vile fire spawned at the wrong location]] | ||
− | | | + | | Undisputed |
− | | | + | | Typo |
! N | ! N | ||
! N | ! N | ||
Line 105: | Line 129: | ||
! N | ! N | ||
! Y | ! Y | ||
+ | |- | ||
+ | | [[Blockmap overflow]] | ||
+ | | Undisputed | ||
+ | | Overflow | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
|- | |- | ||
| [[Broadcast packet meltdown]] | | [[Broadcast packet meltdown]] | ||
Line 135: | Line 167: | ||
! N | ! N | ||
! N | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | |- | ||
+ | | [[Crash when accessing Read This!]] [http://www.doomworld.com/vb/doom-general/73271-solved-the-mystery-of-the-alternative-doom95-exe/] | ||
+ | | Undisputed | ||
+ | | | ||
+ | ! Y | ||
+ | ! | ||
! N | ! N | ||
! N | ! N | ||
Line 187: | Line 227: | ||
|- | |- | ||
| [[Elastic collisions with walls]] | | [[Elastic collisions with walls]] | ||
− | | | + | | Undisputed |
− | | | + | | Roundoff |
! N | ! N | ||
! N | ! N | ||
Line 212: | Line 252: | ||
| [[Final Doom teleporters do not set Z coordinate]] | | [[Final Doom teleporters do not set Z coordinate]] | ||
| Undisputed | | Undisputed | ||
+ | | Algorithm | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | |- | ||
+ | | [[Firing frame position not updated when the player dies]] | ||
+ | | | ||
| Algorithm | | Algorithm | ||
! N | ! N | ||
Line 456: | Line 504: | ||
! N | ! N | ||
! N | ! N | ||
+ | ! N | ||
+ | |- | ||
+ | | [[Manual doors on 1S lines cause an illegal operation]] | ||
+ | | Undisputed | ||
+ | | Linedef | ||
+ | ! Y* | ||
+ | ! N | ||
+ | ! Y | ||
! N | ! N | ||
|- | |- | ||
Line 513: | Line 569: | ||
! N | ! N | ||
! | ! | ||
+ | |- | ||
+ | | [[Monsters may target players without ever seeing or hearing them]] | ||
+ | | Disputed | ||
+ | | Algorithm | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
|- | |- | ||
| [[Monsters open locked doors]] | | [[Monsters open locked doors]] | ||
Line 546: | Line 610: | ||
! N | ! N | ||
|- | |- | ||
− | | [[ | + | | [[Vertical offsets are ignored in texture patches]] |
| Undisputed | | Undisputed | ||
| Algorithm | | Algorithm | ||
Line 605: | Line 669: | ||
| | | | ||
| | | | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | |- | ||
+ | | [[Partial invisibility effect#Animation remains still|Partial invisibility's fuzz effect stays still]] | ||
+ | | | ||
+ | | Algorithm | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | |- | ||
+ | | [[Partial invisibility effect#Stippling effect|Partial invisibility stippling algorithm]] | ||
+ | | Disputed | ||
+ | | Algorithm | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | |- | ||
+ | | [[Pause bug in menus with scroll bars]] | ||
+ | | Undisputed | ||
+ | | Algorithm | ||
! N | ! N | ||
! N | ! N | ||
Line 682: | Line 770: | ||
! | ! | ||
|- | |- | ||
− | | [[PWAD size limit] | + | | [[PWAD size limit]] |
| Undisputed | | Undisputed | ||
| Algorithm | | Algorithm | ||
Line 704: | Line 792: | ||
!N | !N | ||
!Y | !Y | ||
+ | !N | ||
+ | |- | ||
+ | | [[Random sound pitch removed]] | ||
+ | | | ||
+ | | | ||
+ | !N | ||
+ | !N | ||
+ | !N | ||
!N | !N | ||
|- | |- | ||
Line 712: | Line 808: | ||
! N | ! N | ||
! N | ! N | ||
+ | ! Y | ||
+ | |- | ||
+ | | [[Blast damage#Non-reentrancy|Recurrent blast damage]] | ||
+ | | Undisputed | ||
+ | | Algorithm | ||
+ | ! N | ||
+ | ! N | ||
+ | ! S | ||
! Y | ! Y | ||
|- | |- | ||
Line 719: | Line 823: | ||
! Y | ! Y | ||
! Y | ! Y | ||
+ | ! N | ||
+ | ! N | ||
+ | |- | ||
+ | | [[Revenant tracers desync internal demos]] | ||
+ | | Undisputed | ||
+ | | Algorithm | ||
+ | ! N* | ||
+ | ! N | ||
! N | ! N | ||
! N | ! N | ||
Line 760: | Line 872: | ||
! N | ! N | ||
! Y | ! Y | ||
+ | ! N | ||
+ | |- | ||
+ | | [[Secret#Bugs|Secret sectors appear or disappear]] | ||
+ | | | ||
+ | | Algorithm | ||
+ | ! N | ||
+ | ! N | ||
+ | ! S | ||
! N | ! N | ||
|- | |- | ||
Line 774: | Line 894: | ||
| Static limit | | Static limit | ||
! N | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | ! Y | ||
+ | |- | ||
+ | | [[Single-use line actions can fail]] | ||
+ | | Undisputed | ||
+ | | Algorithm | ||
+ | ! N* | ||
! N | ! N | ||
! N | ! N | ||
Line 892: | Line 1,020: | ||
| [[Sprites flickering across ledges or lifts]] | | [[Sprites flickering across ledges or lifts]] | ||
| Disputed | | Disputed | ||
+ | | Algorithm | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | ! N | ||
+ | |- | ||
+ | | [[Sprites improperly clipped]] | ||
+ | | | ||
| Algorithm | | Algorithm | ||
! N | ! N | ||
Line 914: | Line 1,050: | ||
! N | ! N | ||
|- | |- | ||
− | | [[Starting on a vertex between visplanes causes illegal memory | + | | [[Starting on a vertex between visplanes causes illegal memory access]] |
| Undisputed | | Undisputed | ||
| | | | ||
Line 981: | Line 1,117: | ||
| Undisputed | | Undisputed | ||
| Linedef | | Linedef | ||
+ | ! N | ||
+ | ! N | ||
+ | ! Y | ||
+ | ! N | ||
+ | |- | ||
+ | | [[Unused frames and obstacle sprite]] [http://www.doomworld.com/vb/post/225726] | ||
+ | | | ||
+ | | | ||
! N | ! N | ||
! N | ! N | ||
Line 1,081: | Line 1,225: | ||
* [[Doom source code oddities]] | * [[Doom source code oddities]] | ||
* [[Static limits]] | * [[Static limits]] | ||
+ | * [[Engine bugs in Strife]] | ||
[[Category:Errors and bugs|*]] | [[Category:Errors and bugs|*]] | ||
[[Category:Doom engine]] | [[Category:Doom engine]] | ||
[[Category:Lists]] | [[Category:Lists]] |
Revision as of 06:58, 24 June 2015
A Doom engine bug is a limitation or an oddity present in the Doom engine. For errors in map design, even those related to a specific item below, see the article about that map.
Note that playing with a source port may, while removing some or even the majority of the bugs listed below, introduce other bugs which are not listed here (although details may be present in the article about the source port in question).
Key
This table classifies anomalies in a very broad way; see the individual articles for details.
- Canonicity — A bug is verified only when a current or former id Software programmer has called it a bug in a public medium. An unverified bug may still be undisputed if it is generally accepted as an error or issue by the fan community under a consensus involving thorough playtesting and research on the corresponding phenomenon and any associated binaries or source code. A bug is disputed if it can be argued to be a harmless and possibly intentional feature.
- Cause — The general category of underlying problem:
- Most bugs are due to algorithms which fail to account for all possible inputs, apply conditional statements in an illogical sequence, or have unforeseen consequences in particular game situations.
- A few of these arise from simple typos in the source code.
- Improperly constructed linedefs (with orphaned tags or incorrectly placed textures) or sectors, can also induce various strange behaviors.
- The Doom engine includes few safeguards against overflow conditions.
- Line-of-sight calculations, rendering algorithms, and the BSP tree are also susceptible to roundoff errors.
- The engine imposes a number of static limits on Thing placement and map construction, which sometimes fix one problem by creating another.
- Most bugs are due to algorithms which fail to account for all possible inputs, apply conditional statements in an illogical sequence, or have unforeseen consequences in particular game situations.
- Fatal bugs are those where the engine crashes (often with the Venetian blind effect) or else exits the game in a controlled fashion, usually with an error message. Y* means that termination is possible, but not inevitable. N* means that the program keeps running, but that rendering or character behavior may be sufficiently compromised that meaningful gameplay becomes impossible.
- A bug has a workaround if it can be avoided by reasonable compromises in map design, such as when matching every linedef tag to at least one sector, but not when removing invulnerabilities from every level containing a sky texture, or also by convenient precautions and other measures taken by the program user, such as when increasing the mouse sensitivity through the configuration file directly, instead of using the menu. S means that the bug can be avoided only by making one's map smaller or less complex.
- A bug is a loophole if it can be abused to the player's advantage (especially during speedruns or deathmatches).