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Howto:Start core development: Difference between revisions
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{{out of date}} | |||
''01/2012: I have taken my {{forum link|p=146436|text=forum response}} and copied/pasted it here. Everybody is invited to contribute. While we do have a [[Volunteer]] page, we don't currently have a page dedicated to people wanting to contribute to the C++ source code, so this is an attempt to get something like this started.'' | |||
= How the Project works (Suggested reading!) = | |||
* [[http://home.flightgear.org/flightgear-policy-document/ | Flightgear Policy Document briefly covering what will be expected of a contributor]] | |||
* [[http://home.flightgear.org/info/ | Other Information to be Aware Of]] | |||
* {{forum link|p=149971|title=Flightgear Development}} | |||
* [[How the FlightGear project works]] | |||
Please see this short essay here: {{forum url|p=149971}} | |||
Also see [[Implementing new features for FlightGear]] | |||
= Welcome to FlightGear = | = Welcome to FlightGear = | ||
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The "Nasal" programming language built into FG is syntactically very close to C and C++, it looks a lot like JavaScript - so you could run your own code inside FG without having to build FG from source, no need for compilers or an IDE. FlightGear IS the run time environment for Nasal code. | The "Nasal" programming language built into FG is syntactically very close to C and C++, it looks a lot like JavaScript - so you could run your own code inside FG without having to build FG from source, no need for compilers or an IDE. FlightGear IS the run time environment for Nasal code. | ||
If you are looking for immediate results, Nasal is probably the most promising route - simply because you don't need to look into all the tedious, non-coding related issues. | If you are looking for immediate results, Nasal is probably the most promising route - simply because you don't need to look into all the tedious, non-coding related issues. Here's an overview giving you a rough idea about recent Nasal related efforts: | ||
{{Nasal Efforts}} | |||
For example, the tutorial system built into FG is entirely implemented in scripting space, and fully XML-configurable: [[Tutorials]] | For example, the tutorial system built into FG is entirely implemented in scripting space, and fully XML-configurable: [[Tutorials]] | ||
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The FlightGear project uses the decentralized source code management system "git" see [[Git]] for more info. | The FlightGear project uses the decentralized source code management system "git" see [[Git]] for more info. | ||
The project sources are hosted at | The project sources are hosted at sourceforge: https://sourceforge.net/p/flightgear/flightgear/ci/next/tree/ | ||
If you know for sure that you'd like to fiddle with the core source code, you'll inevitably need to be able build FG from source, this is also documented in our wiki, a more recent article is to be found here: http://wiki.flightgear.org/Howto:_Build_FlightGear_with_NetBeans_using_CMake | If you know for sure that you'd like to fiddle with the core source code, you'll inevitably need to be able build FG from source, this is also documented in our wiki, a more recent article is to be found here: http://wiki.flightgear.org/Howto:_Build_FlightGear_with_NetBeans_using_CMake | ||
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= Continuous Integration (CI) = | = Continuous Integration (CI) = | ||
For CI purposes, there's a dedicated build server running which rebuilds the FlightGear sources for a handful of important platforms. The server provides a simple and quick overview, it can be found here: | For CI purposes, there's a dedicated build server running which rebuilds the FlightGear sources for a handful of important platforms. The server provides a simple and quick overview, it can be found here: {{build link}} | ||
Please see [[FlightGear Build Server]] for more information. | Please see [[FlightGear Build Server]] for more information. | ||
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Note that this article is meanwhile somewhat deprecated and these days using gitorious (and filing merge requests there) is pretty much encouraged. If your patch is related to a previously reported bug/defect, you can obviously also use the issue tracker (see below). | Note that this article is meanwhile somewhat deprecated and these days using gitorious (and filing merge requests there) is pretty much encouraged. If your patch is related to a previously reported bug/defect, you can obviously also use the issue tracker (see below). | ||
In general, the FlightGear gitorious project is the entry point for new developers | In general, the FlightGear gitorious project is the entry point for new developers. | ||
Some more recommendations can be found at [[Recommended Project Policies]]. | Some more recommendations can be found at [[Recommended Project Policies]]. | ||
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In developer's terms, that mostly boils down to: | In developer's terms, that mostly boils down to: | ||
* expect more and more scenery functionality to be procedurally added (e.g. [[Terragear_roadmap#Runtime_Airport_Generation|runways, taxiways]], whole airports) | |||
* expect more and more viewer functionality to be decoupled from the simulator (fgviewer being the prototype here) | * expect more and more viewer functionality to be decoupled from the simulator (fgviewer being the prototype here) | ||
* expect more and more viewer/GUI features to be made optional through a [[FlightGear Headless]] mode during startup | * expect more and more viewer/GUI features to be made optional through a [[FlightGear Headless]] mode during startup | ||
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* expect [[FGPanel|FGPanel standalone panel rendering]] functionality to be merged back into the main fgfs code base, provided through [[FGViewer]] | * expect [[FGPanel|FGPanel standalone panel rendering]] functionality to be merged back into the main fgfs code base, provided through [[FGViewer]] | ||
* expect more work towards better system-wide reinit/reset support: http://wiki.flightgear.org/Reset_%26_re-init | * expect more work towards better system-wide reinit/reset support: http://wiki.flightgear.org/Reset_%26_re-init | ||
* expect more and more launcher features to be integrated and provided as part of FlightGear | * expect more and more launcher features to be integrated and provided as part of FlightGear {{forum link|p=191451}} | ||
* expect FDMs to become re-initializable at runtime, expect support for multiple FDMs per session | * expect FDMs to become re-initializable at runtime, expect support for multiple FDMs per session | ||
* expect more subsystem to become re-initializable at runtime, so that they can be dynamically enabled/disabled to facilitate the fgviewer and headless efforts: http://wiki.flightgear.org/FlightGear_Run_Levels | * expect more subsystem to become re-initializable at runtime, so that they can be dynamically enabled/disabled to facilitate the fgviewer and headless efforts: http://wiki.flightgear.org/FlightGear_Run_Levels | ||
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Also, there's another outdated category titled "Code Cleanup": http://wiki.flightgear.org/Category:Code_Cleanup | Also, there's another outdated category titled "Code Cleanup": http://wiki.flightgear.org/Category:Code_Cleanup | ||
Another option would be taking a look at the "Google Summer of Code" category which also lists project ideas collected over the years: [[GSoC: Candidate Projects]]. We also have a separate sub forum for GSoC here: | Another option would be taking a look at the "Google Summer of Code" category which also lists project ideas collected over the years: [[GSoC: Candidate Projects]]. We also have a separate sub forum for GSoC here: {{forum url|f=38}} | ||
In other words: '''pick your poison :)''' | In other words: '''pick your poison :)''' | ||
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There's a fully searchable archive available here: http://www.mail-archive.com/flightgear-devel@lists.sourceforge.net/ | There's a fully searchable archive available here: http://www.mail-archive.com/flightgear-devel@lists.sourceforge.net/ | ||
In addition, the FlightGear forums are increasingly used for interesting development related discussions, please note though that these are usually not specific to FG core development, but instead general development (aircraft, scenery, shaders, scripting): | In addition, the FlightGear forums are increasingly used for interesting development related discussions, please note though that these are usually not specific to FG core development, but instead general development (aircraft, scenery, shaders, scripting): {{forum url}} | ||
If there's something particular that you are interested in, it's always a good idea to search these resources (wiki, forum, mailing list) to find related discussions. | If there's something particular that you are interested in, it's always a good idea to search these resources (wiki, forum, mailing list) to find related discussions. | ||
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= Important docs = | = Important docs = | ||
There's a wealth of documentation to get you started available in | There's a wealth of documentation to get you started available in {{fg root file|Docs}} | ||
API docs auto generated from source are at http://api-docs.freeflightsim.org/ | |||
Even more documentation can be found in our wiki, here: http://wiki.flightgear.org/ | Even more documentation can be found in our wiki, here: http://wiki.flightgear.org/ | ||
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The SimGear code base is somewhat less archaic and more modern actually. And if you are interested in contributing to the OpenGL/SceneGraph department, you'll inevitably need to look into OpenSceneGraph (OSG), too - which really is "modern C++". | The SimGear code base is somewhat less archaic and more modern actually. And if you are interested in contributing to the OpenGL/SceneGraph department, you'll inevitably need to look into OpenSceneGraph (OSG), too - which really is "modern C++". | ||
SimGear is fairly well-maintained code base that contains a fair amount of doxygen comments, that means that it's easy to create doxygen documentation for SimGear. For example, see: http:// | SimGear is fairly well-maintained code base that contains a fair amount of doxygen comments, that means that it's easy to create doxygen documentation for SimGear. For example, see: http://api-docs.freeflightsim.org/simgear/ | ||
Note that, at the time of reading, this may be outdated, so if you are interested in using the latest doxygen docs, you are well advised to run doxygen against your own latest simgear clone. | Note that, at the time of reading, this may be outdated, so if you are interested in using the latest doxygen docs, you are well advised to run doxygen against your own latest simgear clone. | ||
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If your C++ is rusty and you'd just like to get started quickly, there are also certain FG components that are strictly (largely) pure C, the Nasal interpreter is just one example (Nasal is FlightGear's built in scripting language): http://wiki.flightgear.org/Nasal_scripting_language | If your C++ is rusty and you'd just like to get started quickly, there are also certain FG components that are strictly (largely) pure C, the Nasal interpreter is just one example (Nasal is FlightGear's built in scripting language): http://wiki.flightgear.org/Nasal_scripting_language | ||
The Nasal interpreter is part of the SimGear project, and can be found in $SG_SRC/nasal: | The Nasal interpreter is part of the SimGear project, and can be found in $SG_SRC/nasal: {{simgear url|trees/next/simgear/nasal}} | ||
The longest-standing issue related to Nasal scripting is fixing its Garbage Collector (GC) to become generational, incremental or even concurrent, this is to reduce main loop impact (frame rate & frame spacing), see [[How the Nasal GC works]] to learn more. Almost certainly, we're going to adopt an existing GC library, or even implement an interface to experiment with different GC schemes, and allow those to be selected at startup. | |||
Adding new extension functions to the built-in Nasal interpreter is documented here: [[Howto: Extend Nasal]]. | Adding new extension functions to the built-in Nasal interpreter is documented here: [[Howto: Extend Nasal]]. | ||
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None of this requires any C++ knowledge! | None of this requires any C++ knowledge! | ||
Only the scripting interface connecting the Nasal interpreter and FlightGear is implemented in C++, it can be found in | Only the scripting interface connecting the Nasal interpreter and FlightGear is implemented in C++, it can be found in {{fg src file|Scripting}} | ||
Basically, the scripting interface implements a custom SGSubsystem, so that the Nasal interpreter can be run as a FlightGear system. In addition, all FlightGear-specific extension functions are to be found there. Increasingly, this folder also contains wrappers to map FlightGear classes to Nasal space in an OOP fashion, so that not just functions, but full "objects" are provided, which are computed lazily. If that's what you are interested in, you should take a look at the | Basically, the scripting interface implements a custom SGSubsystem, so that the Nasal interpreter can be run as a FlightGear system. In addition, all FlightGear-specific extension functions are to be found there. Increasingly, this folder also contains wrappers to map FlightGear classes to Nasal space in an OOP fashion using the [[Nasal/CppBind]] framework, so that not just functions, but full "objects" are provided, which are computed lazily. If that's what you are interested in, you should take a look at the NasalPositioned_cppbind.cxx source code, which demonstrates how this is done. | ||
In other words, even without knowing C++, you can contribute to FlightGear core by extending the Nasal system. If you have some specific project in mind, you could probably implement it largely in scripting space using Nasal and only augment it as required with new extension functions in C space. | In other words, even without knowing C++, you can contribute to FlightGear core by extending the Nasal system. If you have some specific project in mind, you could probably implement it largely in scripting space using Nasal and only augment it as required with new extension functions in C space. | ||
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== JPEGFactory == | == JPEGFactory == | ||
{{Note|Also see [http://sourceforge.net/p/flightgear/mailman/flightgear-devel/thread/053287a7-005d-4fd0-a1ee-96f1194ea904%40email.android.com/#msg32398628]}} | |||
{{cquote|actually the entire JPEGFactory option could likely be removed, and replaced with using the osgDB Image plugins to create a JPEG or PNG. And then it wouldn't need to be a CMake option at all. If anyone would like to attempt this, please ask and I can suggest where to start, it's a nice small project<ref>{{cite web |url=http://www.mail-archive.com/flightgear-devel@lists.sourceforge.net/msg40211.html|title=<nowiki>Re: [Flightgear-devel] Enabling JPEG factory causes fgfs/GIT to fail compiling</nowiki>|author=James Turner|date=Tue, 11 Jun 2013 22:40:38 -0700}}</ref>|James Turner}} | {{cquote|actually the entire JPEGFactory option could likely be removed, and replaced with using the osgDB Image plugins to create a JPEG or PNG. And then it wouldn't need to be a CMake option at all. If anyone would like to attempt this, please ask and I can suggest where to start, it's a nice small project<ref>{{cite web |url=http://www.mail-archive.com/flightgear-devel@lists.sourceforge.net/msg40211.html|title=<nowiki>Re: [Flightgear-devel] Enabling JPEG factory causes fgfs/GIT to fail compiling</nowiki>|author=James Turner|date=Tue, 11 Jun 2013 22:40:38 -0700}}</ref>|James Turner}} | ||
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We could probably also look at using the [[Canvas]] system with some additional hooks, i.e. for getting a handle to the osg::Image, so that it can be serialized through Nasal and some cppbind glue, that would make it possible to depreciate the JPEGFactory code and use the Canvas system instead (i.e. unifying the 2d rendering backend). | We could probably also look at using the [[Canvas]] system with some additional hooks, i.e. for getting a handle to the osg::Image, so that it can be serialized through Nasal and some cppbind glue, that would make it possible to depreciate the JPEGFactory code and use the Canvas system instead (i.e. unifying the 2d rendering backend). | ||
Being able to render camera views to a canvas texture has been previously requested a number of times, e.g. for implementing "mirrors" or tail cameras (A380) | Being able to render camera views to a canvas texture has been previously requested a number of times, e.g. for implementing "mirrors" or tail cameras (A380) {{forum link|t=13798}} {{forum link|p=184284}} {{forum link|t=13798}} {{forum link|t=6184}} {{forum link|p=31252}}, and getting a handle to the buffer for serialization purposes would also allow us to reimplement the screenshot feature on top of canvas/Nasal, and even serve live image data through the httpd component. | ||
* [[Howto:Use a Camera View in an Instrument]] | * [[Howto:Use a Camera View in an Instrument]] | ||