Source

Source
Engine Name
Developer Name	Valve
Max Supported Players
Games Made
Steam integration
Website

Source is a 3D video game engine developed by Valve Corporation. It debuted as the successor to GoldSrc with Counter-Strike: Source in June 2004, followed shortly by Half-Life 2 in November, and has been in active development since. Source does not have a concise version numbering scheme; instead, it is designed in constant incremental updates.<ref name="develop-11" /> The successor, Source 2, was officially announced in March 2015, with the first game to use it being Dota 2, which was ported over from Source later that year.

History

Source distantly originates from the GoldSrc engine, itself a heavily modified version of John Carmack's Quake engine. Carmack commented on his blog in 2004 that "there are still bits of early Quake code in Half-Life 2".<ref>Template:Cite web</ref> Valve employee Erik Johnson explained the engine's nomenclature on the Valve Developer Community:<ref name="goldsrc-src-quote">Template:Cite web</ref>

Source was developed part-by-part from this fork onwards, slowly replacing GoldSrc in Valve's internal projects<ref>Template:Cite book</ref> and, in part, explaining the reasons behind its unusually modular nature. Valve's development of Source since has been a mixture of licensed middleware and in-house-developed code. Among others, Source uses Bink Video for video playback.<ref>Template:Cite news</ref>

Modularity and notable upgrades

Source was created to evolve incrementally with new technology, as opposed to the backward compatibility-breaking "version jumps" of its competitors. Different systems within Source are represented by separate modules which can be updated independently. With Steam, Valve can distribute these updates automatically 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.<ref>Template:Cite web</ref> Both cases 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.Template:Citation needed

Since Source engine's release in 2004, the following major architectural changes have been made:

Source 2006

File:Half-Life 2 Episode One Citadel Base.jpg

A screenshot of Half-Life 2: Episode One. The high dynamic range rendering and Phong shading effects are evident.

The Source 2006 branch was the term used for Valve's games using technology that culminated with the release of Half-Life 2: Episode One. HDR rendering and color correction were first implemented in 2005 using Day of Defeat: Source, which required the engine's shaders to be rewritten.<ref name="hdr_shaders">Template:Cite video game</ref> The former, along with developer commentary tracks, were showcased in Half-Life 2: Lost Coast. Episode One introduced Phong shading and other smaller features. Since the transition to Steam Pipe, this branch was made deprecated and is now used for backward compatibility with older mods.Template:Citation needed Image-based rendering technology had been in development for Half-Life 2,<ref name="driverheaven-2003">Template:Cite web</ref> 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 that are impossible with strictly polygonal objects.<ref name="1up-valveweek">Template:Cite web</ref>

Source 2007

The Source 2007 branch represented a full upgrade of the Source engine for the release of The Orange Box. An artist-driven, threaded particle system replaced previously hard-coded effects for all of the games within.Template:Cn An in-process tools framework was created to support it, which also supported the initial builds of Source Filmmaker. In addition, the facial animation system was made hardware-accelerated on modern video cards for "feature film and broadcast television" quality.<ref name="steamnews_meetheavy">Template:Cite web</ref> The release of The Orange Box on multiple platforms allowed for a large code refactoring, which let the Source engine take advantage of multiple CPU cores.<ref name="PCZone">Template:Cite web</ref> However, support on the PC was experimental and unstable<ref name="steam-forum-mat_queue_mode">Template:Cite web</ref> until the release of Left 4 Dead.<ref name="left-4-dead-multicore">Template:Cite web</ref> Multiprocessor support was later backported to Team Fortress 2 and Day of Defeat: Source.<ref>Template:Cite web</ref> Valve created the Xbox 360 release of The Orange Box in-house, and support for the console is fully integrated into the main engine codeline. It includes asset converters, cross-platform play and Xbox Live integration.<ref name="official_consoles">Template:Cite web</ref> Program code can be ported from PC to Xbox 360 simply by recompiling it.<ref name="joystiq_source360">Template:Cite web</ref> The PlayStation 3 release was outsourced to Electronic Arts, and was plagued with issues throughout the process. Gabe Newell cited these issues when criticizing the console during the release of The Orange Box.<ref>Template:Cite news</ref>

Left 4 Dead branch

The Left 4 Dead branch was a complete overhaul of the Source engine through the development of the Left 4 Dead series. Multiprocessor support was further expanded, allowing for features like split screen multiplayer, additional post-processing effects, event scripting with Squirrel, and the highly-dynamic AI Director. The menu interface was re-implemented with a new layout designed to be more console-oriented. This branch later fueled the releases of Alien Swarm and Portal 2, the former released with source code outlining many of the changes made since the branch began. Portal 2, in addition, served as the result of Valve taking the problem of porting to PlayStation 3 in-house, and in combination with Steamworks integration creating what they called "the best console version of the game".<ref>Template:Cite web</ref>

OS X, Linux, and Android support

In April 2010, Valve released all of their major Source games on OS X, coinciding with the release of the Steam client on the same platform. Valve announced that all their future games will be released simultaneously for Windows and Mac.<ref>Template:Cite web</ref><ref>Template:Cite web</ref> 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. Both the OS X and Linux ports of the engine take advantage of OpenGL and are powered by SDL.<ref>Template:Cite web</ref> During the process of porting, Valve rearranged most of the games released up to The Orange Box into separate, but parallel "singleplayer" and "multiplayer" branches. The game code to these branches was made public to mod developers in 2013, and they serve as the current stable release of Source designated for mods. Support for Valve's internal Steam Pipe distribution system as well as the Oculus Rift are included.<ref>Template:Cite web</ref> In May 2014, Nvidia released ports of Portal and Half-Life 2 to their Tegra 4-based Android handheld game console Nvidia Shield.<ref>Template:Cite web</ref>

Source 2

As far back as May 2011, one of Valve's largest projects has been the development of new content authoring tools for Source.<ref name="develop-11">Template:Cite web</ref> These would replace the current outdated tools, allowing content to be created faster and more efficiently. Newell has described the creation of content with the engine's current toolset as "very painful" and "sluggish".<ref>Template:Cite web</ref> Valve officially announced the engine at the Game Developers Conference in March 2015, also stating that it would be free to use for developers, with support for the Vulkan graphical API.<ref>Template:Cite web</ref><ref>Template:Cite web</ref> In addition, Valve confirmed that it would be using a new in-house physics engine named Rubikon.<ref name=":0">Template:Cite web</ref> In 2015, Dota 2 was ported over to Source 2 in an update called Dota 2 Reborn, making it the first game to use the engine.<ref>Template:Cite web</ref><ref>Template:Cite magazine</ref><ref>Template:Cite web</ref> The engine has since been used for Artifact and Dota Underlords, with a version of the engine that runs on Android and iOS devices.<ref>Template:Cite web</ref>

Tools and resources

Source SDK

File:Source SDK Launcher.jpg

The launcher menu for Source SDK

Source SDK is the software development kit for the Source engine, and contains many of the tools used by Valve to develop assets for their games. It comes with several command-line programs designed for special functions within the asset pipeline, as well as a few GUI-based programs designed for handling more complex functions. Source SDK was launched as a free standalone toolset through Steam, and required a Source game to be purchased on the same account. Since the release of Left 4 Dead in late 2008, Valve began releasing "Authoring Tools" for individual games, which constitute the same programs adapted for each game's engine build. After Team Fortress 2 became free-to-play, Source SDK was effectively made open to all Steam users. When some Source games were updated to Source 2013, the older Source SDKs were phased out. The three applications mentioned below are now included in the install of each game.

There are three applications packaged in the Source SDK: Hammer Editor, Model Viewer, and Face Poser. Hammer Editor, the engine's official level editor, uses rendering and compiling tools included in the SDK to create maps using the binary space partitioning (BSP) method. The tool was originally known as Worldcraft and was developed independently by Ben Morris before Valve acquired it.<ref>Template:Cite web</ref> The Model Viewer is a program that allows users to view models and can be used for a variety of different purposes, including development. Developers may use the program to view models and their corresponding animations, attachment points, bones, and so on. Face Poser is the tool used to access facial animations and choreography systems. This tool allows one to edit facial expressions, gestures and movements for characters, lip sync speech, and sequence expressions and other acting cues and preview what the scene will look like in the game engine.

Source Dedicated Server

The Source Dedicated Server or SRCDS is a standalone launcher for the Source engine that runs multiplayer game sessions without requiring a client. It can be launched through Windows or Linux, and can allow for custom levels and assets. Most third-party servers additionally run Metamod:Source and SourceMod, which together provide a framework on top of SRCDS for custom modification of gameplay on existing titles.<ref>Template:Cite web</ref><ref>Template:Cite web</ref>

Source Filmmaker

Template:Main The Source Filmmaker (SFM) is a video capture and editing application that works from within the Source engine.<ref name=sfm_home>Template:Cite web</ref> Developed by Valve, the tool was originally used to create movies for Day of Defeat: Source, but is more associated with Team Fortress 2. Today, it is open for public use and downloadable via the Steam client.

Destinations Workshop Tools

In June 2016, Valve released the Destinations Workshop Tools, a set of free virtual reality (VR) creation tools running using the Source 2 SDK.<ref>Template:Cite web</ref>

Valve Developer Community

In June 2005, Valve opened the Valve Developer Community (VDC) wiki.Template:Cn 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, Valve's non-player character AI, advice for mod teams on setting up source control, and other articles.

Academic papers

Valve staff occasionally produce professional and/or academic papers for various events and publications, including SIGGRAPH, Game Developer Magazine and Game Developers Conference, explaining various aspects of Source engine's development.<ref name="Valve Publications">Template:Cite web</ref>

Games

Source

Valve games

• Half-Life 2 (2004)
• Half-Life 2: Deathmatch (2004)
• Half-Life: Source (2004)
• Counter-Strike: Source (2004)
• Day of Defeat: Source (2005)
• Half-Life 2: Lost Coast (2005)
• Half-Life Deathmatch: Source (2006)
• Half-Life 2: Episode One (2006)
• Half-Life 2: Episode Two (2007)
• Team Fortress 2 (2007)
• Portal (2007)
• Left 4 Dead (2008)
• Left 4 Dead 2 (2009)
• Alien Swarm (2010)
• Portal 2 (2011)
• Counter-Strike: Global Offensive (2012)

Games by other developers

• Vampire: The Masquerade – Bloodlines<ref>Template:Cite web</ref> (2004)
• Garry's Mod (2006)
• SiN Episodes (2006)
• Dark Messiah of Might and Magic (2006)
• The Ship (2006)
• Kuma\War (2006)
• Dystopia (2007)
• Insurgency: Modern Infantry Combat (2007)
• Zombie Panic! Source (2007)
• Silent Hill Alchemilla (2015)
• Zeno Clash<ref>Template:Cite web</ref> (2009)
• NeoTokyo (2009)
• Bloody Good Time (2010)
• Vindictus (2010)
• Pirates, Vikings and Knights II (2010)
• E.Y.E.: Divine Cybermancy (2011)
• No More Room in Hell (2011)
• Nuclear Dawn (2011)
• Postal III (2011)
• Dino D-Day (2011)
• Dear Esther (2012)
• Black Mesa (2012)
• Tactical Intervention (2013)
• The Stanley Parable (2013)
• Blade Symphony (2014)
• Consortium (2014)
• Contagion (2014)
• Insurgency (2014)
• Titanfall (2014)
• Fistful of Frags (2014)
• Portal Stories: Mel (2015)
• The Beginner's Guide (2015)
• Infra (2016)
• Titanfall 2 (2016) (modified)<ref>Template:Cite web</ref>
• Day of Infamy (2017)
• Apex Legends (2019) (modified)<ref>Template:Cite web</ref>

Source 2

• Dota 2 (2013) (ported from Source in 2015)
• The Lab (2016) (Robot Repair only; rest of the minigames were created with the Unity engine)
• Artifact (2018)
• Dota Underlords (2019)

See also

• First-person shooter engine
• List of Source engine mods