Editing Doom engine (section)

{{short description|1993 game engine}}
{{DISPLAYTITLE:''Doom'' engine}}
{{Infobox video game engine
| name = id Tech 1
| logo = 
| screenshot = 
| caption = [[Doom (1993 video game)|Doom]] running on the ''Doom Engine''.
| collapsible = 
| author = 
| developer = [[id Software]] (John Carmack, John Romero, Dave Taylor)
| replaces = [[Wolfenstein 3D engine]]
| replaced_by = [[Quake engine]]
| latest release version = 1.9
| latest release date = {{release date and age|1995|02|01}}
| repo = [https://github.com/id-Software/DOOM github.com/id-Software/DOOM]
| tools = 
| programming language = [[C (programming language)|C]], [[Assembly language]]
| platform = [[MS-DOS]], [[PC-98]], [[Microsoft Windows|Windows]], [[Mac (computer)|Mac]], [[Linux]], [[Android (operating system)|Android]], [[Amiga]], [[NeXTSTEP]], [[NeXT]], [[Atari Jaguar|Jaguar]], [[32X]], [[PlayStation]], [[3DO Interactive Multiplayer|3DO]], [[Nintendo 64]], [[Sega Saturn|Saturn]], [[Game Boy Advance]], [[Nintendo Switch|Switch]], [[BSD]], [[Unix]], others
| discontinued = yes
| license = [[GNU General Public License|GNU GPL-2.0-or-later]]<ref>{{cite web |title=Doom source code, under the GNU GPL |url=https://www.gamers.org/pub/idgames/source/doomsrc.txt |website=gamers.org |archive-url=https://web.archive.org/web/20230531233251/https://www.gamers.org/pub/idgames/source/doomsrc.txt |archive-date=31 May 2023 |url-status=live}}</ref><br />[[List of Doom ports#3DO Interactive Multiplayer|3DO]]: [[MIT license|MIT]]<ref>{{Cite web|url=https://github.com/Olde-Skuul/doom3do/blob/master/LICENSE|title=Doom3do/LICENSE at master · Olde-Skuul/Doom3do|website=[[GitHub]]|date=17 December 2022|access-date=14 February 2019|archive-date=19 February 2022|archive-url=https://web.archive.org/web/20220219155118/https://github.com/Olde-Skuul/doom3do/blob/master/LICENSE|url-status=live}}</ref>
}}

'''id Tech 1''', also known as the '''''Doom'' engine''', is the [[game engine]] used in the [[id Software]] [[video game]]s ''[[Doom (1993 video game)|Doom]]'' and ''[[Doom II: Hell on Earth]]''. It is also used in ''[[Heretic (video game)|Heretic]]'', ''[[Hexen: Beyond Heretic]]'', ''[[Strife (1996 video game)|Strife: Quest for the Sigil]]'', ''[[Doom WAD#Total conversions|Hacx: Twitch 'n Kill]]'', ''[[Freedoom]]'', and other games produced by licensees. It was created by [[John D. Carmack|John Carmack]], with auxiliary functions written by [[Mike Abrash]], [[John Romero]], [[Dave D. Taylor|Dave Taylor]], and Paul Radek. Originally developed on [[NeXT]] computers,<ref>{{Cite web |title=NeXT Computers - Company - Computing History |url=http://www.computinghistory.org.uk/det/927/NeXT-Computers/ |access-date=2022-03-29 |website=www.computinghistory.org.uk |archive-date=2022-03-29 |archive-url=https://web.archive.org/web/20220329152654/http://www.computinghistory.org.uk/det/927/NeXT-Computers/ |url-status=live }}</ref> it was [[porting|ported]] to [[MS-DOS]] and compatible operating systems for ''Doom''<nowiki>'</nowiki>s initial release and was later ported to several [[game console]]s and [[operating system]]s.

The [[source code]] to the [[Linux]] version of ''Doom'' was released to the public under a license that granted rights to non-commercial use on December 23, 1997, followed by the Linux version of ''Doom II'' about a week later on December 29, 1997.<ref>{{cite web|archive-url=https://web.archive.org/web/19980218070336/http://www.pcgamer.com/news/news-1997-12-29.html |url=http://www.pcgamer.com:80/news/news-1997-12-29.html |title=Doom II Source Available |author=Staff |work=[[PC Gamer US]] |date=December 29, 1997 |archive-date=February 18, 1998 |url-status=dead |access-date=November 20, 2019 |df=mdy-all }}</ref><ref>https://web.archive.org/web/*/ftp://ftp.idsoftware.com/idstuff/source/* {{cite web |url=ftp://ftp.idsoftware.com/idstuff/source/ |archive-url=https://web.archive.org/web/20151202080952/ftp://ftp.idsoftware.com/idstuff/source/ |archive-date=2015-12-02 |url-status=dead |title=FTP link |work=ftp.idsoftware.com }}</ref> The source code was later re-released under the [[GNU General Public License|GNU General Public License v2.0 or later]] on October 3, 1999.<ref>{{Cite web |url=https://www.doomworld.com/idgames/source/doomsrc |title=Doom source code, under the GNU GPL - Doomworld /idgames database frontend |access-date=2021-03-28 |archive-date=2021-03-28 |archive-url=https://web.archive.org/web/20210328161448/https://www.doomworld.com/idgames/source/doomsrc |url-status=live }}</ref><ref>
[http://www.3ddownloads.com/showfile.php3?file_id=7430 The ''Doom'' source code from 3ddownloads.com] {{webarchive |url=https://web.archive.org/web/20040224122359/http://www.3ddownloads.com/showfile.php3?file_id=7430 |date=February 24, 2004 }} - released in 1997, now under the [[GNU GPL]] v2-or-later</ref>
The dozens of unofficial [[Doom source ports|''Doom'' source ports]] that have been created since then allow ''Doom'' to run on previously unsupported operating systems and sometimes radically expand the engine's functionality with new features.

Although the engine renders a 3D space, that space is projected from a two-dimensional [[floor plan]]. The line of sight is always parallel to the floor, walls must be perpendicular to the floors, and it is not possible to create multi-level structures or sloped areas (floors and ceilings with different angles). Despite these limitations, the engine represented a technological leap from id's previous [[Wolfenstein 3D engine|''Wolfenstein 3D'' engine]]. The ''Doom'' engine was later renamed{{Citation needed|date=August 2024|reason=There is no source for 'id Tech 1' being the official name of this engine. The cited Giant Bomb article doesn't say anything about this. id Software's licensing site didn't feature an 'id Tech 1', only id Tech 2. Before the introduction of this brand in 2007, the licensing page only featured the three Quake engines.
https://web.archive.org/web/20070501000000*/http://www.idsoftware.com/business/technology}} to "id Tech 1" in order to categorize it in a list of [[id Tech|id Software's long line of game engines]].<ref>{{cite web |title=id Tech 1 (Concept) |url=http://www.giantbomb.com/id-tech-1/3015-3803/ |website=[[Giant Bomb]] |access-date=2019-02-14 |archive-date=2019-02-15 |archive-url=https://web.archive.org/web/20190215050335/https://www.giantbomb.com/id-tech-1/3015-3803/ |url-status=live }}</ref>