- Id Tech 4
Infobox Software
name = id Tech 4
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developer =id Software
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programming language =C++
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platform =Windows ,Linux ,PlayStation 3 ,Xbox 360 ,Macintosh [cite web |url=http://www.mobygames.com/game-group/3d-engine-id-tech-4 |title=3D Engine: id Tech 4 |accessdate=2008-09-24]
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genre =Game engine
license = proprietary [cite web |url=http://www.idsoftware.com/business/idtech4/ |title=Id Software: Technology Licensing |accessdate=2008-09-24] ;GNU General Public License planned for 2009 [cite web |url=http://www.linuxgames.com/archives/10532 |title=QuakeCon Recap |accessdate=2008-09-24]
website =id Tech 4, formerly known as the Doom 3 engine, is a computer
game engine developed byid Software and first used in the PC game "Doom 3 ". The engine was designed by John Carmack, who also created previous engines such as those for Doom and Quake, which are also generally recognized as marking significant advances in the field.History
The Doom 3 engine began as an enhancement to
id Tech 3 . Originally it was planned to be a complete rewrite of the engine's renderer, while still retaining other subsystems, such as file access, and memory management. After the new renderer was functional, however, the decision was made to switch from C to theC++ programming language , necessitating a complete restructuring and rewrite of the rest of the engine; today, while the Doom 3 engine contains code from id Tech 3, much of it has had to be rewritten.Like its predecessors, id Tech 4 will eventually be released as
open source . At theQuakeCon 2007, John Carmack the lead graphics engine developer at id, said toLinuxGames :"I mean I won't commit to a date, but the Doom 3 stuff will be open source." [ [http://www.linuxgames.com/archives/9374 LinuxGames - Embrace your inner penguin ] ]Hardware
A disadvantage of id Tech 4 was that it needed a high-end graphics processing unit (GPU), which was at least DirectX 8.0 compliant with fully programmable vertex and pixel shaders, such as the
Nvidia GeForce 3 orATI Radeon 8500 , with at least 64 MB of VRAM. By E3 2002, the recommended GPU was theRadeon 9700 with 128 VRAM; while its DirectX 9.0 features are not necessary to render the game, its advanced architecture, 256-bit memory bus, and efficiency were needed to run Doom 3 at high detail and playable speed. [http://www.neowin.net/news/main/02/07/20/atis-radeon-9700-takes-performance-lead]id Tech 4 resulted in the obsolescence of DirectX 7.0 graphics chips such as the widespread
GeForce 2 and Radeon 7200, as well as DirectX 6.0 chipsets such asRIVA TNT2 andRage 128 , and software rendering (with an integratedIntel GMA ). Until the advent of id Tech 4, a powerful CPU was able to somewhat compensate for an older video card. While John Carmack initially warned gamers not to purchase theGeForce 4 MX (which casual consumers often confused with the DirectX 8.0 GeForce 4 Ti, though it was at best an improved DirectX 7.0GeForce 2 ), its somewhat widespread adoption compelled id Software to enable Doom 3 to run on these cards, making it the only DirectX 7.0 chip capable of doing so. There have been cases of enthusiasts forcingDoom 3 to run on unsupported graphics chips, such as the long obsoleteVoodoo 2 , but these are unable to render the per-pixel lighting and bump mapping. [http://www.3dfxzone.it/enboard/topic.asp?TOPIC_ID=1462]Features
Graphics
The Doom 3 engine added several new graphical features absent in its predecessor,
id Tech 3 . These includedbump mapping ,normal mapping , andspecular highlight ing. More features were added in the development of successive games, and in yet unreleased games using the Doom 3 engine, new features have been added or are planned to be added soon.The primary innovation of the Doom 3 engine was its use of entirely dynamic
per-pixel lighting , whereas previously, 3D engines had relied primarily on pre-calculated per-vertex lighting orlightmap s andGouraud shading . While dynamic effects had been available before (such as dynamic moving lights), this effect merely changed the brightness of the vertices of the polygon with the pixels being simply interpolated between the three colours. The approach used in "Doom 3" permitted more realistic lighting and shadows [ [http://www.digit-life.com/articles2/doom3/doom3.html Doom 3 ] ] that just had been introduced in video games [for example http://www.starbreeze.com/engine.jsp and others] .Games using or licensing the Doom 3 engine
Unlike the preceding and widely-used id Tech 3 (Quake III Engine) and id Tech 2 (Quake II Engine), the Doom 3 engine has had somewhat less success in licensing to third parties. This is especially apparent in comparison to its closest competitor, the Unreal 3 engine. The unexpected long development time going into id Tech 4 did not help, as between 2002-2004, id Software had no equivalent to the Unreal 2 engine. Many who licensed the Unreal 2 engine were thus able to make the switch to Unreal 3 more easily.
While id Tech 4 had taken a new direction with its dynamic
per-pixel lighting , this unconventional feature had steeper hardware requirements and was initially only useful in "spooky games" (until theMegaTexture addition), whereas an increasing number of developers preferred conventional engines that could render large outdoor areas. Also notable was id Tech 4's relative lack of scalability compared to competing FPS engines which would have limited its potential audience; theSource Engine could still run on the older widespread DirectX 7 GPUs albeit without shaders being used.*"
Doom 3 " –id Software
**"" –Nerve Software
*"Quake 4 " –Raven Software
*"Prey" –Human Head Studios
*"" –Splash Damage
*"Wolfenstein –Raven Software MegaTexture rendering technology
The original version of the Doom 3 engine was criticized for its perceived inability to handle large outdoor areas. The MegaTexture technology addresses this issue by introducing a means to create expansive outdoor scenes. By painting a single massive texture (32,768×32,768
pixel s, though it has been extended to larger dimensions in recent versions of the MegaTexture technology) covering the entire polygon map and highly detailed terrain, the desired effects can be achieved. The MegaTexture can also store physical information about the terrain such as the amount of traction in certain areas or indicate what sound effect should be played when walking over specific parts of the map. i.e. walking on rock will sound different from walking on grass. [ [http://pc.gamespy.com/pc/enemy-territory-quake-wars/681231p1.html GameSpy: Enemy Territory: Quake Wars Preview ] ] It is expected that this will result in a considerably more detailed scene than the majority of existing technologies, using tiled textures, allow. Currently, the only game that utilizes MegaTexture based on the Tech 4 engine is "".Techniques used in the Doom 3 engine
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Unified lighting and shadowing
*Shadow volume ee also
*
List of game engines
*First person shooter engine References
* [http://money.cnn.com/2004/08/12/commentary/game_over/column_gaming CNN - Life after "Doom"]
* [http://pc.gamespy.com/pc/enemy-territory-quake-wars/681231p1.html Gamespy article from which some information on MegaTexture was derived]
* [http://www.digit-life.com/articles2/doom3/doom3.html Article detailing some features of the Doom 3 engine]
* [http://www.linuxgames.com/news/feedback.php?identiferID=9374&action=flatview]External links
* [http://iddevnet.com/ Official MOD support website for the Doom 3 engine]
* [http://www.doom3world.org/phpbb2/index.php Technical Help Forum & Custom Content Creation]
* [http://www.modwiki.net/wiki/Main_Page Doom 3 engine reference material]
* [http://www.moddb.com/engines/7/id-tech-4 id Tech 4's ModDB page containing mod listing, tutorials, and more]
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