Source (game engine)
|This article may need to be rewritten entirely to comply with Wikipedia's quality standards. (May 2012)|
|Stable release||Build 5247 / 2013|
Source is a 3D video game engine developed by Valve Corporation. It debuted in June 2004 with Counter-Strike: Source, followed shortly by Half-Life 2, and has been in active development ever since. Unusually for a game engine, Source does not have a meaningful version numbering scheme; instead, it is designed in constant incremental updates.
Source was created to power first-person shooters, but has also been used professionally to create role-playing, side-scroller, puzzle, MMORPG, top-down shooter and real-time strategy games.
Notable technology 
The Source engine implements:
- Direct3D rendering on Microsoft Windows PCs, Xbox and Xbox 360, OpenGL rendering on Mac OS X, Linux and the PlayStation 3.
- High dynamic range rendering, or HDR.
- Lag-compensated client-server networking model
- Network-enabled and bandwidth-efficient physics engine (derived from Havok).
- Scalable multiprocessor support
- Pre-computed radiosity lighting and dynamic shadow maps. Deferred lighting is supported on consoles.
- Facial animation system. Lip-sync using the system is auto-generated and localizable.
- Blended skeletal animation system, including inverse kinematics
- Water flow effects
- Dynamic 3D wounds
- Alpha to coverage edge smoothing for foliage etc.
- Map-logic scripting with Squirrel (programming language).
- Significant source code access for mod teams
- Distributed map compiler
- Cloth simulation (introduced in Dota 2)
Source Filmmaker 
The Source Filmmaker (SFM) is a video capture and editing application that works from within Source. Developed by Valve, the tool was used to create movies for Team Fortress 2, the Left 4 Dead series, Portal 2, and more.
Modularity and notable upgrades 
Source was created to evolve incrementally as technology moves onwards, as opposed to the backwards compatibility-breaking "version jumps" of its competitors. With Steam, Valve can distribute automatic updates with new versions of the engine among its many users.
In practice however, there have been occasional breaks in this chain of compatibility. The release of Half-Life 2: Episode One and The Orange Box both introduced new versions of the engine that could not be used to run older games or mods without the developers performing upgrades to code and, in some cases, content. Both cases, however, required markedly less work to update its version than competing engines. This was demonstrated in 2010, when Valve updated all of their core Source games to the latest engine build.
Since Source's release in 2004, the following major architectural changes have been made:
- High dynamic range rendering (2005, Day of Defeat: Source)
- Simulation of a camera aperture and the ability to fake the effects of brightness values beyond computer monitors' actual range. Required all of the game's shaders to be rewritten.
- "Soft" particles (2007, The Orange Box)
- An artist-driven, threaded particle system replaced previously hard-coded effects.
- Hardware facial animation (2007, The Orange Box)
- Hardware accelerated on modern video cards for "feature film and broadcast television" quality.
- Multiprocessor support (2007, The Orange Box)
- A large code refactoring allowed the Source engine to take advantage of multiple CPU cores on the PC, Xbox 360 and PlayStation 3. On the PC, support was experimental and unstable until the release of Left 4 Dead. Multiprocessor support was later backported to Team Fortress 2 and Day of Defeat: Source.
- Xbox 360 support (2007, The Orange Box)
- Valve created the Xbox 360 release of The Orange Box in-house, and support for the console, unlike support for the PlayStation 3, is fully integrated into the main engine codeline. It includes asset converters, cross-platform play and Xbox Live integration. Program code can be ported from PC to Xbox 360 simply by recompiling it.
- PlayStation 3 support (2007, The Orange Box)
- Source first appeared on the PlayStation 3 in 2007, but with an engine port that was created externally and which was plagued with issues. Valve took the problem in-house for Portal 2, and in combination with Steamworks integration created what they called "the best console version of the game".
- Mac OS X support (2010, multiple games)
- In April 2010 Valve released all of their major Source games on Mac OS X. All future Valve games will be released simultaneously for Windows and Mac. Games will only use Direct3D on Windows, and only OpenGL on the other platforms.
- Linux support (2012, multiple games)
- The first of Valve's games to support Linux was Team Fortress 2, the port released in October 2012 along with the closed beta of the Linux version of Steam.
Future technology 
|This section requires expansion. (March 2013)|
As of May 2011, one of Valve's largest projects is the development of new content authoring tools for Source. These will replace the current outdated tools, allowing content to be created faster and more efficiently. Studio head Gabe Newell has described the creation of content with the engine's current toolset as "very painful" and "sluggish".
Source 2 engine 
In August 2012, the Valve fan site ValveTime revealed that Valve might be in development of a "Source 2" engine. The announcement was based on coding from the Source Filmmaker that directed technology from the upcoming version. Later that year, in November, Gabe Newell confirmed that a Source 2 engine is under development, and that Valve is "waiting for a game to roll it out with".
Image-based rendering 
Image-based rendering technology had been in development for Half-Life 2 but was cut from the engine before its release. It was mentioned again by Gabe Newell in 2006 as a piece of technology he would like to add to Source to implement support for much larger scenes than are possible with strictly polygonal objects.
Source distantly originates from the GoldSrc engine, itself a heavily modified version of John D. Carmack's Quake engine, as is explained by Valve employee Erik Johnson on the Valve Developer Community:
|“||When we were getting very close to releasing Half-Life (less than a week or so), we found there were already some projects that we needed to start working on, but we couldn't risk checking in code to the shipping version of the game. At that point we forked off the code in VSS to be both
Source was developed part-by-part from this fork onwards, slowly replacing GoldSrc in Valve's internal projects and, in part, explaining the reasons behind its unusually modular nature. Valve's development of Source since has been a mixture of licensed middleware (Havok Physics, albeit heavily modified, and MP3 playback) and in-house-developed code.
The Source SDK tools are criticised for being outdated and difficult to use. A large number of the tools, including those for texture and model compilation, require varying levels of text-editor scripting from the user before they are executed at the command line; with sometimes lengthy console commands. This obtuseness was cited by the University of London when they moved their exploration of professional architectural visualisation in computer games to Bethesda Softworks' Gamebryo-based Oblivion engine after a brief period with Source. Third-party tools provide GUIs, but are not supported by Valve.
Valve is currently creating a new set of tools.
Valve Developer Community 
On June 28, 2005, Valve opened the Valve Developer Community Wiki. VDC replaced Valve's static Source SDK documentation with a full MediaWiki-powered community site; within a matter of days Valve reported that "the number of useful articles nearly doubled". These new articles covered the previously undocumented Counter-Strike: Source bot (added by the bot's author, Mike Booth), Valve's NPC AI, advice for mod teams on setting up source control, and other articles.
Valve staff occasionally produce papers for various events and publications, including SIGGRAPH, Game Developer Magazine and Game Developers Conference, explaining various aspects of Source's development. They are aimed at professional audiences and often discuss complex concepts. They are listed on Valve's corporate website.
See also 
|Wikimedia Commons has media related to: Source (game engine)|
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- "Steamcast #47". Steamcast. February 9, 2011. Retrieved August 14, 2011. "Oh yeah, we're spending a tremendous amount of time on tools right now. So, our current tools are... very painful, so we probably are spending more time on tools development now than anything else and when we’re ready to ship those I think everybody's life will get a lot better. Just way too hard to develop content right now, both for ourselves and for third-parties so we’re going to make enormously easier and simplify that process a lot."
- Evans-Thirlwell, Edwin (2012-08-06). "Valve's Source Engine 2 outed, Half-Life 3 delay explained?".
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- "Source Engine 2 in the works at Valve – report". VG247. 2012-11-12. Retrieved 2013-02-15.
- Conditt, Jessica (2012-11-11). "Newell: Valve building Source 2 engine, Ricochet 2 is in development". Joystiq. Retrieved 2013-02-15.
- "Source Engine 2 is being worked on, Valve are just "waiting for a game to roll it out with"". TweakTown. US. 2012-11-12. Retrieved 2013-02-15.
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