View source for QuakeC

{{short description|Compiled language}}
{{Infobox programming language
| name                   = QuakeC
| paradigm               = [[imperative programming|imperative]] ([[Procedural programming|procedural]]), [[structured programming|structured]]
| designer               = [[John Carmack]]
| developer              = [[id Software]]
| typing                 = [[Type system|static]], [[Strong typing|strong]]
| implementations        = Quake C Compiler, FastQCC, FTEQCC, QCCx, GMQCC
| year                   = 1996
| file ext               = .qc 
| turing-complete        = No
| influenced_by          = [[C (programming language)|C]]
}}

'''QuakeC''' is a [[compiled programming language|compiled language]] developed in 1996 by [[John D. Carmack|John Carmack]] of [[id Software]] to program parts of the [[video game]] ''[[Quake (video game)|Quake]]''. Using QuakeC, a programmer is able to customize ''Quake'' to great extents by adding weapons, changing game logic and physics, and programming complex scenarios. It can be used to control many aspects of the game itself, such as parts of the AI, triggers, or changes in the level. The [[Quake engine|''Quake'' engine]] was the only [[game engine]] to use QuakeC. Following engines used [[Dynamic-link library|DLL]] game modules for customization written in [[C (programming language)|C]], and [[C++]] from [[id Tech 4]] on.

== Overview ==
The QuakeC source to the original [[id Software]] ''Quake'' game logic was published in 1996 and used as the basis for modifications like [[capture the flag]] and others.<ref>{{cite web |url=http://www.satanicslaughter.com/news/?news_id=94 |title=QuakeC released |author=Lasse Lehtinen |date=1996-07-25 |work=Quake and QuakeWorld history |access-date=2011-01-14 |archive-date=2011-07-16 |archive-url=https://web.archive.org/web/20110716005831/http://www.satanicslaughter.com/news/?news_id=94 |url-status=dead }}</ref> QuakeC source code is compiled using a tool called [[qcc]] into a [[bytecode]] kept in a file called {{mono|progs.dat}}.  The programmers of ''Quake'' modifications could then publish their {{mono|progs.dat}} bytecode without revealing their [[source code]].  Most ''Quake'' mods were published this way.

QuakeC allowed the [[Quake engine|''Quake'' engine]] to dominate the direction of the [[first-person shooter]] genre.{{CN|date=April 2020}} Thanks to Carmack's idea of extending video game life by adding unlimited expandability (extensibility already played a big role in ''[[Doom (1993 video game)|Doom]]''), an enormous Internet community of gamers and programmers alike has arisen and many modern multiplayer games are extensible in some form.{{Citation needed|date=March 2009}}

QuakeC is known as interpreted because as ''Quake'' runs, it is continually interpreting the progs.dat file.<ref>{{cite web |url=http://www.bluesnews.com/guide/quakec2.htm |title=Quake C Basics |author=Andrew Wu |access-date=2013-04-06}}</ref>

== Limitations and subsequent solutions ==
The [[syntax]] of QuakeC is based on that of the [[C (programming language)|C programming language]], explaining its name, but it does not support the implementation of new types, structures, arrays, or any kind of referencing other than the "entity" type (which is always a reference). QuakeC also suffers from the fact that many built-in functions (functions prototyped in the QuakeC code but actually defined within the game engine and written in C) return strings in a temporary string buffer, which can only hold one string at any given time. In other words, a construct such as

:<code>SomeFunction (ftos (num1), ftos (num2));</code>

will fail because the second call to <code>ftos</code> (which converts a floating-point value to a string) overwrites the string returned by the first call before SomeFunction can do something with it. QuakeC does not contain any string handling functions or file handling functions, which were simply not needed by the original game.

Most video games at the time had their game logic written in plain C/C++ and [[compiler|compiled]] into the executable, which is faster. However, this makes it harder for the community to create [[Mod (computer gaming)|mods]] and it makes the process of [[porting]] the game to another platform (such as [[Linux]]) more costly.

Despite its advantages, the choice of implementing game logic using a custom scripting language and [[Interpreter (computing)|interpreter]] was dropped from the next generation [[Quake II engine]] in favor of compiled [[C (programming language)|C]] code due to the overall inflexibility of QuakeC, the increasingly complex game logic, the performance to be gained by packaging game logic into a native [[dynamic link library]], and the advantage of leveraging an already established programming language's community, tools, educational materials, and documentation.<ref>{{cite web |last=Carmack |first=John |author-link=John Carmack |title=Here is a technical issue to be discussed, Pg.18 |url=http://fabiensanglard.net/fd_proxy/doom3/pdfs/johnc-plan_1997.pdf#page=19 |date=13 March 1997 |work=[[.plan]] |publisher=[[id Software]] |access-date=5 November 2018}}</ref>

Distributing native code created new security and portability concerns. QuakeC bytecode afforded little opportunity for mischief, while native code has access to the whole machine. QuakeC bytecode also worked on any machine that could run Quake. Compiling to native code added an additional barrier to entry for novice mod developers, because they were being asked to set up a more complicated [[Integrated development environment|programming environment]]. The eventual solution, implemented by the [[Quake III engine]], was to combine the advantages of original QuakeC with the advantages of compiling C to native code. [[LCC (compiler)|LCC]] was extended to compile standard C into bytecode, which could be interpreted by a [[virtual machine]] in a manner similar to QuakeC. This addressed the security, portability, and tool chain problems, but lost the performance advantage of native code. That was solved by further compiling the bytecode into native code at run time on supported machines.<ref>{{cite web |last=Carmack |first=John |author-link=John Carmack |title=Jul 24, 1999, Pg.54 |url=http://fabiensanglard.net/fd_proxy/doom3/pdfs/johnc-plan_1999.pdf#page=54 |date=24 July 1999 |work=[[.plan]] |publisher=[[id Software]] |access-date=5 November 2018}}</ref>

== Modified compilers and language extensions ==
A decompiler and a recompiler were released by [[Armin Rigo]] (called <code>DEACC</code> and <code>REACC</code> respectively). These programs were made through the process of [[reverse engineering]], and were most likely published before the release of <code>qcc</code>.<ref>{{Cite web|url=http://users.yknet.yk.ca/dmckay/qmap/inter.html|title=Interview with Armin Rigo - Feb. 12th 1997|date=April 30, 1997|archive-url=https://web.archive.org/web/19970430160107/http://users.yknet.yk.ca/dmckay/qmap/inter.html|archive-date=1997-04-30}}</ref>

[[id Software]] released the source of <code>qcc</code>, their QuakeC compiler, along with the original QuakeC code in 1996. Modified versions soon sprung up, including Jonathan Roy's <code>fastqcc</code> and Ryan "FrikaC" Smith's [[FrikQCC]].  These added functionality, optimizations, and compiling speed boosts.

In 1999, when id Software released the code from Quake's engine under the [[GNU General Public License]] (GPL), the workings of the bytecode interpreter were examined and new QuakeC compilers were released, such as J.P. Grossman's <code>qccx</code> and a new version of FrikQCC.  These compilers took advantage of newly discovered features in a backwards-compatible way so that the bytecode could still be properly interpreted by unmodified Quake engines.  New features include arrays, pointers, integers, for loops and string manipulation.

With the ''Quake'' engine source code now able to be changed, further features were added to QuakeC in the form of new built-in functions. Features long yearned for by QuakeC coders finally reached realization as QuakeC now had file and string handling functions, enlarged string buffers, more math functions, and so on.  However, programmers taking advantage of these changes lost backwards compatibility with the unmodified Quake engine.

''[[Xonotic]]'' since version 0.7 uses the [https://github.com/graphitemaster/gmqcc gmqcc] compiler.<ref>{{cite web| url = http://www.xonotic.org/2013/06/xonotic-0-7-release/| title = Xonotic 0.7 Release}}</ref>

== Client-side QuakeC ==
Some enhanced ''Quake'' engines (notably [[DarkPlaces engine|DarkPlaces]] and FTEQW){{clarify|What is FTEQW?|date=July 2021}} have support for an extension of regular QuakeC (now commonly referred to as server-side QuakeC) that allows client-side-only scripting of the ''Quake'' engine, also abbreviated as CSQC (client-side QuakeC). This is especially useful for GUIs, HUDs{{Clarify|reason=What do these letters mean?|date=August 2021}} and any visually heavy effects that do not need to be simulated on the server and transferred over the network.<ref>{{Cite web|url=http://www.quakewiki.net/darkplaces-wiki/client-side-quakec/|title=Client-Side QuakeC|website=QuakeWiki|date=30 September 2012 |access-date=2016-11-16}}</ref>

== See also ==
* [[Quake modding]]
* [[Video game modding]]
* [[Computer programming]]

== References ==
{{reflist}}

== External links ==
* [https://github.com/id-Software/Quake-Tools/tree/master/qcc id's github repository containing the C source code of qcc (QuakeC compiler)]
* [https://github.com/id-Software/Quake/tree/master/qw-qc id's github repository containing the QuakeC source code to QuakeWorld game logic]
* [http://www.gamers.org/dEngine/quake/spec/quake-spec34/qc-menu.htm Unofficial QuakeC specifications]
* [http://www.gamers.org/pub/idgames2/quakec/ Large collection of QC mods, including their source]
* [http://www.insideqc.com/qctut/ Inside3d - nice collection of QC tutorials here]
* [http://www.insideqc.com/ InsideQC - New website to inherit Inside3D's legacy after it was shut down]

{{Quake}}

{{DEFAULTSORT:Quakec}}
[[Category:Domain-specific programming languages]]
[[Category:Video game development]]
[[Category:Quake (series)]]
[[Category:Scripting languages]]
[[Category:Id Tech]]
[[Category:Statically typed programming languages]]