Difference between revisions of "User:Callahanp"

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I am a flight simulation hobbyist currently working on building instruments, gauges, radios and controls for a C172.  
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== What I'm doing: ==
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While I participate very marginally in flightgear-devel, I'm ramping up my C++11 skills, learning more about git, getting to know a few editors, IDEs, Build and Debugging tools.  I hope to eventually be able 24-7 to build and effectively debug flightgear on any operating system, and to be able to support anyone else wishing to do so.
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At the same time, I'm trying to form a coherent view of Flightgear's structure as an application.  Not as a user, but as a developer.  This involves gaining knowledge of the various subsystems that make up flightgear, the underlying technologies each subsystem uses and the flow of control and data  between these subsystems.
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 +
The techniques are the same as any other developer faced with a new 'job' with unfamiliar tools, a new programming language, and a new social environment.  Select some tools from among those used by others on the project. Learn the ins and outs of those tools.  Get a look at every menu item, configuration item, dialog or other interface and get a good sense of how that fits with the tasks of a developer. Find a small problem to examine and perhaps solve, get some advice, try different approaches, ask about the approaches used by others.  Learn or deepen your knowledge of the prevailing coding language or languages. Study the way people on the project behave.  Find out what's important, Find out what's not.  Try to understand where the group is headed and how they think they'll get there.
  
== What I'm doing: ==
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Technically, dig in to the code to learn how it is built, debugged and run.  Know about all the configuration items.  Find all the big pieces in its hierarchy of objects.  Some of them are important to know well.  Others it is important to know of their existence.  Some you can just be marginally aware of.  Any that deal with subsystems, creating visual elements, communication between subsystems or keeping things running correctly from cycle to cycle are important.  Fine details can wait till later.
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 +
[http://wiki.flightgear.org/User:Callahanp/git-workflow Git Workflow]
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 +
[http://wiki.flightgear.org/User:Callahanp/fg-from-scratch  Callahanp - Flightgear From Scratch]
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[http://wiki.flightgear.org/User:Callahanp/Flightgear_Technical_Manual Callahanp - Flightgear Technical Manual]
  
===[http://wiki.flightgear.org/User:Callahanp/fg-from-scratch Flightgear From Scratch]===
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[http://wiki.flightgear.org/User:Callahanp/Flightgear_and_Simgear_Code Flightgear and Simgear Code]
  
===[http://wiki.flightgear.org/User:Callahanp/FlightgearWorkingGroups Flightgear Working Groups]===
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[http://wiki.flightgear.org/User:Callahanp/FlightgearWorkingGroups Callahanp - Flightgear Working Groups]
  
==== [[https://github.com/c172p-team/c172p C172P Team on Github ]] ====
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[[https://github.com/c172p-team/c172p C172P Team on Github ]]
  
Proposed:
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=== Development Operations ===
  
* Subsystem Management Group
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I am making an effort to define and give detailed examples of development file and repository operations for various parts of Flightgear Code and Data including all SourceForge Git repositories, Scenery, Aircraft, Aircraft Hangars, Airport Data. Add-Ons and anything else that can be used with Flightgear.  This will include items that fall under the FlightGear SourceForge project, and other projects that do not.
* Property Tree Dwellers
 
* Vulcanologists
 
* Plib Janitors
 
* FDM Dev
 
* Flightgear Dev Onboarding
 
* Flightgear Dev Scenery
 
* Flightgear Dev Core
 
* Flightgear Dev Aircraft  
 
* Flightgear Dev Airports
 
* Cockpit Builders
 
  
===[http://wiki.flightgear.org/User:Callahanp/Flightgear_and_Simgear_Code Flightgear and Simgear Code]===
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This Page will be organized not around specific kinds of development, but around the development operations common to all of them. Operations include obtaining source materials, preparatory steps, ongoing operational readiness tasks, building, modifying, debugging, testing, and submitting changes.   I'll explain further and give examples of the individual operations needed to accomplish these tasks for all types of FlightGear material, whether source code or data, regardless of the type of file or where it's upstream repository resides. 
  
Several years ago I began the effort to fully understand the skills needed to contribute to the Flightgear project's codebaseI started to look through various parts of the Flightgear code-base to understand how the parts fit together and how supporting libraries are used in the project.  
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When finished, this guide is intended to be comprehensive up to a point.  If you participate in the development of anything used with or within flightgear, with few exceptions, you'll be able to find information on specific commands and procedures needed to complete the listed operational tasksWe'll leave to other pages, specifics of the internals of working on files of different types, and the kinds of edits and additions that should be made within a file. and focus on the environments that support the actual work to be done and on the resulting files, giving their types, and generally describing contents, without going into details.
  
This is an ongoing effort hampered by lack of time, my obsolete C++ training obtained in the early 1990's.
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The page is currently under rapid development, with attention focused currently on correctly obtaining source materials for C & C++ programming of the main application.  Where expansion is needed to cover other types of materials, we'll add a note soliciting your input on what should be said.
  
There's a LOT of code.  Where do you start?
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Here are a few examples of the Operations of each type:
  
 
{| class="wikitable"
 
{| class="wikitable"
 
|-
 
|-
! Component !! cxx Files !! hxx files !! cxx lines !! hxx lines
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! Operation Category !! Examples
 
|-
 
|-
| Flightgear || 583 || 548 || 218192 || 104251
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| Preparatory Steps || <li>installing pre-requisite software libraries needed for building flightgear, simgear and possibly plib or OpenSceneGraph</li>
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<li> Collecting information about the exact current location for upstream source code and data </li> <li> Establishing a SourceForge Account</li>
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<li> Creating an SSH Key and readying it for use with Sourceforge </li>
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<li>Understand where and to what extent each pre-requisite library is used withing flightgear and simgear</li>
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<li>Understand all the basic steps needed to build a working flightgear installation using distribution versions of Plib and OpenSceneGraph<li>
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<li>Understand the additional steps needed to build a working flightgear installation using locally built  versions of Plib and OpenSceneGraph<li>
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<li>Installing and Configuring IDE or Editing Software and extensions for use with CMake and for debugging</li>
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<li>Establishing a build script that can be used with multiple branches or commits and which can build Release, RelWithDebInfo and Debug versions of executables</li>
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<li> Ensuring that Ongoing Operational Readiness Tasks are well documented, understood and used as appropriate</li>
 
|-
 
|-
| Simgear || 352 || 396 || 114001 || 64718
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| Obtaining Source Materials || <li>Cloning Flightgear Git Repositories Locally </li> <li>Creating Personal Forks of Flightgear Repositories and cloning them locally </li>
 
|-
 
|-
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| Ongoing Operational Readiness Tasks || <li>Ensuring that when switching branches, that changes on the previously current branch are not lost</li> <li>Ensuring that local clones used in a build are on the correct branch for the desired build</li> <li>Establishing working branches for specific enhancements</li> <li>Ensuring that sufficient testing has been performed before pushing changes upstream</li>
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|-
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| Building || Executing a script containing a series of CMake commands to build specific parts of flightgear </li><li>Executing a script or program that processes data in raw form to produce a different form of data directly usable by FlightGear (OSM data for example) </li>
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|-
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| Modifying || <li>Using an Editor or IDE to modify or add C++ Code </li><li>  Using Blender, GIMP, or other graphical editing tool to do something for an aircraft </li><li>Adding a building to scenery</li>
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|-
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| Debugging || <li>Using the GDB debugger in command line mode </li><li>Using the GDB debugger in an IDE</li><li>Observing position and details of an aircraft, building or other object from multiple points of view in the Flightgear Application </li>
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|-
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| Automated Testing || <li> Writing, Executing or Debugging CPPUnit tests</li>
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|-
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| Submitting changes || <li>Doing a git push to a personal fork for a branch created for a specific set of changes </li>Creating a merge request for changes present on a personal fork.<li></li>
 
|}
 
|}
  
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=== Development Operation Targets ===
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Each of the operation categories listed above applies to a number of separate parts of the Flightgear Puzzle.  A few of these parts together make up the basic application and are treated together.  Others can be treated as if they were optional add-ons to the development process, even if the item itself is vital to the operation of the basic application.
  
==== Tools ====
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{| class="wikitable"
 +
|-
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! Target Executable !! Description !! Source Materials
 +
|-
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| FlightGear  || This executable is the simulator.  It can be built in several ways,  Release, RelWithDebInfo and Debug possibly including optional features such as Compositor and OpenRTI. || Three Sourceforge FlightGear Git Repositories:
 +
* [https://sourceforge.net/p/flightgear/fgdata/ fgdata]
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* [https://sourceforge.net/p/flightgear/simgear/ simgear]
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* [https://sourceforge.net/p/flightgear/flightgear/ flightgear]
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|-
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| FlightGear CPPUnit Tests  || This executable is build separately and can be executed to run all of the CPPUnit based tests at once || Two Sourceforge FlightGear Git Repositories.  They're the same as are used for the main executable above.
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* [https://sourceforge.net/p/flightgear/fgdata/ fgdata]
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* [https://sourceforge.net/p/flightgear/simgear/ simgear]
 +
|-
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| Resource Compiler
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|-
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| Utilities ||There are several utility programs that are part of the flightgear build process ||
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* flightgear/FDM/JSBSim JSBsim_bin
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* flightgear/FDM/YASim yasim
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* flightgear/FDM/YASim yasim-proptest
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* flightgear/Input fgjs
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* flightgear/Input js_demo
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* flightgear/main metar
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* flightgear/utils/fgcom fgcom
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* flightgear/utils/fgelev fgelev
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* flightgear/utils/fgpanel fgpanel
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* flightgear/utils/fgtraffic fgtraffic
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* flightgear/utils/fgviewer fgviewer
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* flightgear/utils/GPSSmooth GPSSmooth MIDGsmooth & UGsmooth
  
[[User:Callahanp/Flightgear_and_Simgear_Code/Tools_for_a_Flightgear_Developer|Tools for a Flightgear Developer]] (see also [[Tools of the Trade]])
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|-
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| Build Systems || There are several ways to build executable programs including but not limited building within an IDE, fg_from_scratch, download_and_compile.sh, Jenkins servers and custom build scripts ||
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* [https://sourceforge.net/p/flightgear/pipeline/ SourceForge Flightgear git pipeline] A Jenkins Build Script
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* [https://sourceforge.net/p/flightgear/fgmeta/ SourceForge Flightgear git fgmeta]
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* [https://sourceforge.net/p/flightgear/windows-3rd-party/ SourceForge Flightgear git windows-3rd-party] This special purpose repository is used when building flightgear on Windows by users who prefer to use pre-built pre-requisite packages.
 +
|-
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| OpenRadar || Example ||
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* [https://sourceforge.net/p/flightgear/openradar/ SourceForge Flightgear git openradar]
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|-
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| Flight Gear's Flight Manual || It's called Get Start || * [https://sourceforge.net/p/flightgear/getstart/ getstart]
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|-
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| Scenery || Example ||  
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* [https://sourceforge.net/p/flightgear/terragear/ SourceForge Flightgear git terragear]  
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* [https://sourceforge.net/p/flightgear/terrafs/ SourceForge Flightgear git terrafs]  
 +
|-
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| Multiplayer Map || Example ||
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* [https://sourceforge.net/p/flightgear/mpmap.js/ SourceForge Flightgear git mpmap]
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|-
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| Navigation Data || Example || Example
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* [https://sourceforge.net/p/flightgear/navdata/ SourceForge Flightgear git navdata]  
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|-
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| Airport Data || Example || Example
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*
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|-
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| Mac Launcher || Example ||
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* [https://sourceforge.net/p/flightgear/maclauncher/ SourceForge Flightgear git maclauncher]  
  
==== From Command Line to Holding Short ====
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|-
 
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| Open Street Maps (OSM) || Example || Example
[[User:Callahanp/Flightgear_and_Simgear_Code/From_Command_Line_to_Holding_Short|From Command Line to Holding Short]]. A look at what gets called when you start Flightgear from the command line until you are on the runwayThis is a work in progress, somewhat stalled after Eduard Auvergne's initial work on subsystems. It needs a re-vamp to make it current and publishable.
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|-
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| Open Scene Graph (OSG)|| Example || Example
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|-
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| Open Scene Graph - Earth (OSG-Earth)|| Example || Example
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|-
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| C172P Skyhawk || The C172P-Team produces the C172P used in Flightgear as the default AircraftA copy of the Aircraft's files is included by the Flightgear project in the SourceForge FlightGear FGData repository||See [https://github.com/c172p-team/c172p C172P-team Github Repository]
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|-
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| Add-On 1 || Example || Example
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|-
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| Add-On 2 || Example || Example
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|-
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| Add-On 3 || Example || Example
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|-
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| Plib || Example || Example
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|}
  
==== Flightgear Application Outline ====
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==== Obtaining Source Materials ====
  
I'm trying to come up with an outline of Flightgear's structure as an application.  
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FlightGear related Source Materials may be hosted in a number of different services.  Depending on the exact material, you may be working with files from the FlightGear Project on SourceForge, other SourceForge projects, projects from GitHub, GitLab or other SCM repository service.  You may be dealing with data that originates in other Simulation Projects, or with code from supporting libraries such as Open Scene Graph.
  
[http://wiki.flightgear.org/User:Callahanp/Flightgear_Technical_Manual| Flightgear Technical Manual]
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Quite a lot of the source materials for the flightgear application are maintained as repositories on SourceForge.  [https://sourceforge.net/p/flightgear/_list/git Complete FlightGear SourceForge Repository List].  Two of these Repositories are no longer used: FGCom and FGRun.  These repositories are obsolete because their functional parts have been included within FlightGear.
  
First Steps:  
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The rest are documented in the section above.
  
===== RTFM =====
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==== Part 1 - Creating a Sourceforge Fork ====
* http://wiki.flightgear.org/FlightGear_Manual
 
* fgdata/doc/img Look at each image in, noting the name of the image and what the image is trying to say
 
* fgdata/doc/keyboard/map.pdf  Note that key bindings can be specific to an aircraft. Note that the pdf was produced from a .tex file.
 
* fgdata/Docs/model-combined.eff/README.model-combined.eff  Read and not What's "rembrandt" - Key terms can be pulled from this document
 
* fgdata/Serial/nmeafaq.txt  Garmin -    Key terms can be pulled from this document.  This document describes a data protocol
 
* AI_doc.html 
 
* FGShortRef.html
 
* http://flightgear.org/Docs/FlightGear-FAQ.html
 
* fgdata/Docs/fschool_0.0.3.pdf
 
* fgdata/Docs/index.html
 
* fgdata/Docs/model-howto.html
 
* and lots of others  - point is you have to read them all
 
  
Once they're read, is there a way to organize them so the result is an overview?
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===== Part 1A - Create a Sourceforge Account, SSH Key and Verify that it works =====
 +
** Requires one personal sourceforge account
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** Requires an ssh login be setup
 +
*** Create an SSH Key for use with Sourceforge
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*** Update Sourceforge SSH Keys
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*** Login to the shell with your key to make sure things are working right.
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*** Logout from the shell - You won't be working there.
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*** Login to Sourceforge on the web.  You will be working with the web interface to sourceforge to create Forks.
  
Sure there is. Just write a book: working title: [Flightgear_Technical_Manual|Flightgear Technical Manual]
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===== Part 1B - Create Sourceforge Forks for each Flightgear git repository you need to work in =====
  
=====It's Data Driven - So Where's the data? =====
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If you are not going to make changes to a particular repository, but only wish to do builds tracking next, you only need a clone of the official Flightgear on your local machine.  You don't need to bother with creating a SourceForge Fork.  You can have a mixture of local gits, some with multiple remote connections origin, upstream and possibly others, others only connected once to flightgear as origin.
  
I've realized that much of the application is data driven, and that data is found in various places. These include files in one or another imaging format .ac files and configuration files of various types including xml files.  Each of these references will involve a path of some kind creating a relationship between material in one file with material in another.  There are path like structures to be found in data structures constructed within the application itself. This happens most notably in the property tree, but also in other independent data structures such as the  structure controlling subsystem initialization, ongoing processing, removal and re-initiialzation. 
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In order not to strain SourceForge resources, it's a good Idea to get rid of any forks that are not used for a while, certainly any that are not used at all for changes and experimental branches. This is especially true of resources that are large.
To uncover some of these relationships and to locate and characterize the various processes involved, a close look at similar code fragments in a large number of files will enable you to uncover patterns that might otherwise elude you.
 
The basic technique will be o use an editor such as Atom, capable of doing a recursive global search through a set of files using a series of regular expressions.  Using regular expressions allows us to go from a more general search to one that is more specific.  All the following examples use atom's find in project - regex - case insensitive search.
 
  
A Question:  What are the major flows of data within the application between components.
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Note that if you later decide to contribute to a new area, or to resume contributing, you will be able to create a fork and attach it to the local clone you previously created using the steps below.
  
The code fragments to search for To get a list of 
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* Open https://sourceforge.net/projects/flightgear/
the include= vs <path> dichotomy is a distinction I'd like to investigate and describe further and the handlers for each of these "types" 
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* Log in to your sourceforge account by clicking the login button if you're logged out.
I thought it might be worth going down the rabbit hole to explore a bit. 
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* Hover over Me and select Profile with a right click and select open link in new window.
  
Keep in mind I'm looking for important concepts that I don't yet have in my outline.  The key to finding them is recognizing the variety of tags found in xml files.  For the moment, I'm looking for tags and other structural identifiers that refer to materials in other files.  
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If you don't see Git under personal tools in your profile page, it's because you've not set up any SourceForge Forks yet.
  
I'm also adding other concepts driven by data from xml files such as  animation, interpolation and the various types of tags with xml files found in the files for the C172p such as checklists, tutorials, instrument and signals.  examples of these are easy to find in an editor capable of text searching an entire project:
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Creating a Sourceforge fork is easy, Just go to the FlightGear Repo you wish to fork and click the fork button on the Left.  It takes a few minutes and is pretty easy to figure out. You'll get to see the clone statement for the repo after refreshing the page after the fork is created.
  
Try the following in atom and you'll see what I mean 
 
  
  cd next/install 
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===== Part 2 - Create a local clone for each Sourceforge Fork  =====
atom . 
 
  
Use the atom FindInProject->Find All with any of the following. Be sure to click on the regex button for the search
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If you already have clones of Flightgear git repos from Sourceforge, there's no need to re-do them as clones of your SourceForge Forks, they can easily be converted using the same steps you would use on a fresh clone of a personal fork.
  
* include=
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** create origin remote
* <path>
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** create upstream remote
* <path>.*\.xml
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** set upstream fetch to main flightgear repositories
* <path>.*\.png
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** create a branch for working on changes
* <path>.*\.ac
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** checkout next
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** checkout a change branch
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** stash changes on a branch
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** push a change branch to your SourceForge fork
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** pull changes from next
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** got fetch
  
etc.
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==== Tools ====
 
Scanning the results of the search for include= reveals that they're all found in fgdata. 
 
  
* All include references to .xml files and the references themselves are found in xml files.
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[[User:Callahanp/Flightgear_and_Simgear_Code/Tools_for_a_Flightgear_Developer|Tools for a Flightgear Developer]] (see also [[Tools of the Trade]])
* There are 2117 of them in 1274 files.
 
* AI/Aircraft alone contains about 75% of the includes.  These are for individual liveries.
 
* Aircraft/c172p gives you a preview of the kind of xml strucures you'll find in any aircraft.  
 
* Aircraft/Generic contains about 5% of the includes. They include items for specific instruments, the walker, a logo,  
 
* ATC  contains a few files with xml includes related to ATIS.Compositor contains several xml includes. This one is likely to be important. 
 
* defaults.xml is likely to be a high level module and therefore important 
 
* Docs contains a number of README.xxxxx files, likely to be informative. Some have xml includes referenced in them. As I've mentioned, you should read every single one.
 
* Instruments contains about 5% of the includes. They include items for specific instruments, the walker, a logo,  
 
* Environment has two files one with filter tags related to xml files describing clouds and the other with tags for cloudLayers and volcanos. 
 
* Input has xml related to joysticks.  there's also a top level file  fgdata/joystics.xml 
 
* Materials makes up the remaining 15% of xml. it includes xml data related to runway textures and effects, buildings, geographic region textures and groups of objects.  
 
  
Scanning for <path> reveals a similar pattern, but <path> is used for more than just .xml files.
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==== From Command Line to Holding Short ====
  
The total of 5067 <path> instances in 1745 files breaks down this way:
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[[User:Callahanp/Flightgear_and_Simgear_Code/From_Command_Line_to_Holding_Short|From Command Line to Holding Short]]. A look at what gets called when you start Flightgear from the command line until you are on the runway. This is a work in progress, somewhat stalled after Eduard Auvergne's initial work on subsystems. It needs a re-vamp to make it current and publishable.
* .ac files with 1868 instances of <path> in  1509 files
 
* .rgb files with 798 in 108 files.
 
* .png files with 55 in 14 files
 
* .jpg 19 in 6 files
 
* .wav 113 in 9 files 
 
* .xsl 2 in 1 file 
 
* .http or .html 3 in 3 files
 
* .xml  with 2138 in 279 files 
 
  
  The xml paths have a similar distribution pattern to the include= xml references, but further investigation is needed to discern how they are different.
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===== RTFM =====
 +
* http://wiki.flightgear.org/FlightGear_Manual
 +
* fgdata/doc/img Look at each image in, noting the name of the image and what the image is trying to say
 +
* fgdata/doc/keyboard/map.pdf Note that key bindings can be specific to an aircraft. Note that the pdf was produced from a .tex file.
 +
* fgdata/Docs/model-combined.eff/README.model-combined.eff  Read and not What's "rembrandt" - Key terms can be pulled from this document
 +
* fgdata/Serial/nmeafaq.txt  Garmin -    Key terms can be pulled from this document.  This document describes a data protocol
 +
* AI_doc.html 
 +
* FGShortRef.html
 +
* http://flightgear.org/Docs/FlightGear-FAQ.html
 +
* fgdata/Docs/fschool_0.0.3.pdf
 +
* fgdata/Docs/index.html
 +
* fgdata/Docs/model-howto.html
 +
* and lots of others  - point is you have to read them all
  
Finally, <path> appears in Comments in 6 files, and is mentioned in 6 readme files.
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Once they're read, is there a way to organize them so the result is an overview?
  
<path> appears in one file 43 times with an <fgproperties> tag
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Sure there is. Just write a book:
  
==== Flightgear and Simgear Directory Descriptions and File Counts ====  
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=== IDEs ===
  
[[User:Callahanp/Flightgear_and_Simgear_Files |Descriptions and file counts of flightgear/src and simgear/simgear subdirectories]]  What's where, What the heck is it anyway?
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Working on Configurations for Visual Studio, Visual Studio Code, Atom, Eclipse and QTCreator IDEs and other tools for working with FlightGear Data.
  
==== Flightgear/Simgear Code Exploration Project ====
+
The day to day work of a FlightGear Developer will include the use of a variety of software to work on various kinds of FlightGear material.
 +
The material includes Source Code written in C and C++, Scripts written in Nasal, Build procedures using CMake and in scripting languages of 3 operating Systems, Data Files representing Airports, Runways, Taxiways, Airport Markings, Navigation Beacons, Instrument Landing System Transmitters, Taxiway and Runway Lighting, Buildings, Roadways,
  
see [http://wiki.flightgear.org/User:Callahanp/Flightgear_and_Simgear_Code Flightgear and Simgear Code]
+
The workflow for all of these has a few basic steps.
  
==== Why I'm reading code ====
+
* Get copies of the original source material
 +
* Establish a fork repository for your changes to the materials
 +
* Make a local copy of the materials
 +
* Change the materials
 +
* Check the Validity of Changes
 +
* Deliver changed materials to your fork
 +
* Request that the changes be accepted and merged with the original source materials.
  
I'll be working on the interface between Flightgear and low level hardware in a panel or cockpit.  It is my understanding that others, including core Flightgear developers are also working on this and my efforts will  follow, derive from, depend on and I hope contribute in some small way to their work.  While I could just focus on the property tree and network interfaces, I still want a basic understanding of all areas of flightgear.
+
The workflows differ based on the true owners of the originating material and the materials format.
  
=== IDEs ===
+
These are the basic tasks that a developer will need to complete
  
Working on Configurations for Eclipse and QTCreator IDEs
+
* Setting up forks of FlightGear Git Archives
 +
* Identifying non-git Open Source Resources for use with Flightgear and establishing forks for them
 +
* Downloading appropriate tools for working on the kind of files that make up the FlightGear application and it's data
 +
* Configuring these tools and FlightGear itself to operate in one or more modes
 +
* Learning the steps to use inside and outside the tools
  
  
 
=== Figuring out how to contribute to FlightGear ===
 
=== Figuring out how to contribute to FlightGear ===
[http://wiki.flightgear.org/User:Callahanp/Flightgear_and_Simgear_Code/Onboarding Onboarding: Getting up to speed]
 
  
 
[[Getting things done in Flightgear]]
 
[[Getting things done in Flightgear]]
  
=== Progress on Cockpit Building ===
 
 
As of Feb 1, 2018:
 
 
* I've done only a few prototype circuits
 
* have been working to develop skills I'll need to produce a realistic cockpit. 
 
* Developing skills in Fusion 360 to support 3d Printing and 3d machine tools.
 
* Working on tests for a cluster based on Raspberry Pi Zeros
 
* Beginning to use a 3d Router
 
* Milling into thin prisms and hand polishing disks of plexiglass for illuminating dials in Sim Instruments
 
  
 
As part of my Cockpit Building efforts, I'm also working on
 
As part of my Cockpit Building efforts, I'm also working on
Line 183: Line 258:
 
  '''[[Special:EmailUser/Callahanp | Email Callahanp through the wiki]]'''
 
  '''[[Special:EmailUser/Callahanp | Email Callahanp through the wiki]]'''
  
I show up occasionally on #flightgear on irc.flightgear.org and am a member of several public forums related to cockpit building.
+
I show up occasionally on discord, #flightgear on irc.flightgear.org and am a member of several public forums related to cockpit building.
  
 
[[User:Callahanp|Callahanp]] ([[User talk:Callahanp|talk]]) 09:45, 11 November 2017 (EST)
 
[[User:Callahanp|Callahanp]] ([[User talk:Callahanp|talk]]) 09:45, 11 November 2017 (EST)
 
=== My Skills ===
 
* Programming in whatever language is available
 
* Databases
 
* Making the following list of chips do what they do:
 
* MCP23XXX Multiplexer
 
* MAX7219 Serially Interfaced, 8-Digit LED Display Driver
 
* Designing a few types of circuits that work on a breadboard (see electronics below)
 
 
===== My Developing Skills -- Beginner =====
 
* Grokking Flightgear's code base.
 
* Very basic machining on a lathe or mill - no significant experience
 
* Electronics - Basics - DC, High & Low speed digital circuits, motor control, emi suppression and mitigation
 
* Soldering - Learn to deal with small components
 
* Designing circuits that make it from breadboard to cockpit.
 
* Getting a cokpit project off the ground
 
 
* C++ - Updating coding skills from an early version of C++
 
 
* Avoiding Writing Howtos
 
 
 
===== My Developing Skills -- Making Good Progress =====
 
 
* Fusion 360 3dCad
 
* 3d Router
 
* Tormach 1100 CNC Mill
 
 
 
=== My Projects ===
 
 
==== [[ C172P Cockpit ]] ====
 
==== [[ Cockpit Inteface for Flightgear ]] ====
 
==== [[ Flightgear Editable Orthographic Views ]] ====
 
==== [[ Up to speed coding C++ for Flightgear ]] ====
 
 
 
===UFO? You decide...  ===
 
 
Flightgear of the Future.
 
 
There's been recent discussion of what it would take to write Flightgear from scratch today.
 
 
I think a better question is how to go about undertaking any major restructuring of Flightgear's codebase to take advantage of modern tools and techniques.  And I think we already have an answer to that.
 
 
In fact, there's an excellent example happening right now in the Spring of 2018. It's Edward's work on unit testing and the restructuring of the subsystem manager.  If you're interested in how big changes come about I'd suggest reading everything related to this effort rather closely and following the ongoing discussion over the need to refactor the way flightgear subsystem dependencies are handled.  Look not just for the technical details, but for the way Edward limited the scope of his current activity and for the quality of the interactions between the interested parties.  I think its a model for anything major anyone wants to undertake in Flightgear.  In fact this kind of interaction is nothing new in the flightgear project.  Other examples abound. Everything from the adoption of OSG to QT has gone through a similar process.
 
 
Those of us who want to be involved in ''big changes'' need to know this process well.  So read the mailing list entries in detail and notice the choices people are making and the reasons why.  The last thing anyone wants is divisive discussion over direction or choices already made. Especially where the root of the discussion is a misunderstanding or refusal to recognize how the project actually works over a period of time.
 
 
So now here's my take on what would be a big Flightgear code change - [[Multicore Processing and Clusters]].  The changes in play today lay the groundwork for this.
 
 
References:
 
* [https://sourceforge.net/p/flightgear/mailman/search/?q=If+you+were+to+write+FlightGear+today... If you were to write FlightGear today... ]
 
* [https://sourceforge.net/p/flightgear/mailman/search/?q=Designs+for+the+subsystem+manager%2Ffactory. Designs for the subsystem manager factory ]
 
* [https://sourceforge.net/p/flightgear/mailman/search/?q=Code+formatting+for+the+whole+FlightGear+codebase Code formatting for the whole FlighGear codebase ]
 
* [https://sourceforge.net/p/flightgear/mailman/search/?q=Questions+about+TestSuite Questions about the TestSuite ]
 
* [https://sourceforge.net/p/flightgear/mailman/search/?q=CppUnit+branches+for+merging%2C+and+an+event+manager+timer+queue+rewri CppUnit branches for merging ]
 
  
 
=== The Howtos ===
 
=== The Howtos ===
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Current Projects:
 
Current Projects:
 
* [[Howto:C172P Panel Project]]
 
* [[Howto:C172P Panel Project]]
* [[Howto:Build your own Panel or Cockpit]]  
+
* [[Howto:Build your own Panel or Cockpit]]
 
 
See below for the my personal rules about these howtos going forward.  I had to write these because it was becoming a morass and time waster.
 
 
 
'''The following is yet another work in progress'''
 
 
 
Writing Advice to Callahanp from Callahanp  or How to write a Howto.
 
 
 
Rule 1. Brevity.
 
 
 
Rule 2. Real Hardware & Software.  If I haven't done it yet I'll talk about it on my personal wiki page.  That's where stuff like that belongs. 
 
 
 
Rule 3. Project Planning, Building Teams, and anything else about developing a hobby project belong elsewhere.  If you want to write about these things, go ahead, but don't do it in a Howto on building something specific like a cockpit.  If you haven't done the project yet you'll get it wrong. Plus, you'll sound like a...
 
 
 
Rule 4. Grand visions, Vaporware, Abstract thinking, Advice and other nonsense  don't belong anywhere. 
 
 
 
Rule 5. Get rid of your darlings.  Those witty turns of phrase, that elegant prose, the puns, jokes and asides.  Fun to write maybe but not so fun to read.  They're distractions.  These are things a skillful writer can weave into an uninterrupted smooth train of thought but you're not that good a writer. Don't even try,
 
 
 
'nuff said.
 

Latest revision as of 04:26, 15 October 2020

What I'm doing:

While I participate very marginally in flightgear-devel, I'm ramping up my C++11 skills, learning more about git, getting to know a few editors, IDEs, Build and Debugging tools.  I hope to eventually be able 24-7 to build and effectively debug flightgear on any operating system, and to be able to support anyone else wishing to do so.

At the same time, I'm trying to form a coherent view of Flightgear's structure as an application.  Not as a user, but as a developer.  This involves gaining knowledge of the various subsystems that make up flightgear, the underlying technologies each subsystem uses and the flow of control and data  between these subsystems.

The techniques are the same as any other developer faced with a new 'job' with unfamiliar tools, a new programming language, and a new social environment. Select some tools from among those used by others on the project. Learn the ins and outs of those tools. Get a look at every menu item, configuration item, dialog or other interface and get a good sense of how that fits with the tasks of a developer. Find a small problem to examine and perhaps solve, get some advice, try different approaches, ask about the approaches used by others. Learn or deepen your knowledge of the prevailing coding language or languages. Study the way people on the project behave. Find out what's important, Find out what's not. Try to understand where the group is headed and how they think they'll get there.

Technically, dig in to the code to learn how it is built, debugged and run. Know about all the configuration items. Find all the big pieces in its hierarchy of objects. Some of them are important to know well. Others it is important to know of their existence. Some you can just be marginally aware of. Any that deal with subsystems, creating visual elements, communication between subsystems or keeping things running correctly from cycle to cycle are important. Fine details can wait till later.

Git Workflow

Callahanp - Flightgear From Scratch

Callahanp - Flightgear Technical Manual

Flightgear and Simgear Code

Callahanp - Flightgear Working Groups

[C172P Team on Github ]

Development Operations

I am making an effort to define and give detailed examples of development file and repository operations for various parts of Flightgear Code and Data including all SourceForge Git repositories, Scenery, Aircraft, Aircraft Hangars, Airport Data. Add-Ons and anything else that can be used with Flightgear. This will include items that fall under the FlightGear SourceForge project, and other projects that do not.

This Page will be organized not around specific kinds of development, but around the development operations common to all of them. Operations include obtaining source materials, preparatory steps, ongoing operational readiness tasks, building, modifying, debugging, testing, and submitting changes. I'll explain further and give examples of the individual operations needed to accomplish these tasks for all types of FlightGear material, whether source code or data, regardless of the type of file or where it's upstream repository resides.

When finished, this guide is intended to be comprehensive up to a point. If you participate in the development of anything used with or within flightgear, with few exceptions, you'll be able to find information on specific commands and procedures needed to complete the listed operational tasks. We'll leave to other pages, specifics of the internals of working on files of different types, and the kinds of edits and additions that should be made within a file. and focus on the environments that support the actual work to be done and on the resulting files, giving their types, and generally describing contents, without going into details.

The page is currently under rapid development, with attention focused currently on correctly obtaining source materials for C & C++ programming of the main application. Where expansion is needed to cover other types of materials, we'll add a note soliciting your input on what should be said.

Here are a few examples of the Operations of each type:

Operation Category Examples
Preparatory Steps
  • installing pre-requisite software libraries needed for building flightgear, simgear and possibly plib or OpenSceneGraph
  • Collecting information about the exact current location for upstream source code and data
  • Establishing a SourceForge Account
  • Creating an SSH Key and readying it for use with Sourceforge
  • Understand where and to what extent each pre-requisite library is used withing flightgear and simgear
  • Understand all the basic steps needed to build a working flightgear installation using distribution versions of Plib and OpenSceneGraph
  • Understand the additional steps needed to build a working flightgear installation using locally built versions of Plib and OpenSceneGraph
  • Installing and Configuring IDE or Editing Software and extensions for use with CMake and for debugging
  • Establishing a build script that can be used with multiple branches or commits and which can build Release, RelWithDebInfo and Debug versions of executables
  • Ensuring that Ongoing Operational Readiness Tasks are well documented, understood and used as appropriate
  • Obtaining Source Materials
  • Cloning Flightgear Git Repositories Locally
  • Creating Personal Forks of Flightgear Repositories and cloning them locally
  • Ongoing Operational Readiness Tasks
  • Ensuring that when switching branches, that changes on the previously current branch are not lost
  • Ensuring that local clones used in a build are on the correct branch for the desired build
  • Establishing working branches for specific enhancements
  • Ensuring that sufficient testing has been performed before pushing changes upstream
  • Building Executing a script containing a series of CMake commands to build specific parts of flightgear
  • Executing a script or program that processes data in raw form to produce a different form of data directly usable by FlightGear (OSM data for example)
  • Modifying
  • Using an Editor or IDE to modify or add C++ Code
  • Using Blender, GIMP, or other graphical editing tool to do something for an aircraft
  • Adding a building to scenery
  • Debugging
  • Using the GDB debugger in command line mode
  • Using the GDB debugger in an IDE
  • Observing position and details of an aircraft, building or other object from multiple points of view in the Flightgear Application
  • Automated Testing
  • Writing, Executing or Debugging CPPUnit tests
  • Submitting changes
  • Doing a git push to a personal fork for a branch created for a specific set of changes
  • Creating a merge request for changes present on a personal fork.
  • Development Operation Targets

    Each of the operation categories listed above applies to a number of separate parts of the Flightgear Puzzle. A few of these parts together make up the basic application and are treated together. Others can be treated as if they were optional add-ons to the development process, even if the item itself is vital to the operation of the basic application.

    Target Executable Description Source Materials
    FlightGear This executable is the simulator. It can be built in several ways, Release, RelWithDebInfo and Debug possibly including optional features such as Compositor and OpenRTI. Three Sourceforge FlightGear Git Repositories:
    FlightGear CPPUnit Tests This executable is build separately and can be executed to run all of the CPPUnit based tests at once Two Sourceforge FlightGear Git Repositories. They're the same as are used for the main executable above.
    Resource Compiler
    Utilities There are several utility programs that are part of the flightgear build process
    • flightgear/FDM/JSBSim JSBsim_bin
    • flightgear/FDM/YASim yasim
    • flightgear/FDM/YASim yasim-proptest
    • flightgear/Input fgjs
    • flightgear/Input js_demo
    • flightgear/main metar
    • flightgear/utils/fgcom fgcom
    • flightgear/utils/fgelev fgelev
    • flightgear/utils/fgpanel fgpanel
    • flightgear/utils/fgtraffic fgtraffic
    • flightgear/utils/fgviewer fgviewer
    • flightgear/utils/GPSSmooth GPSSmooth MIDGsmooth & UGsmooth
    Build Systems There are several ways to build executable programs including but not limited building within an IDE, fg_from_scratch, download_and_compile.sh, Jenkins servers and custom build scripts
    OpenRadar Example
    Flight Gear's Flight Manual It's called Get Start * getstart
    Scenery Example
    Multiplayer Map Example
    Navigation Data Example Example
    Airport Data Example Example
    Mac Launcher Example
    Open Street Maps (OSM) Example Example
    Open Scene Graph (OSG) Example Example
    Open Scene Graph - Earth (OSG-Earth) Example Example
    C172P Skyhawk The C172P-Team produces the C172P used in Flightgear as the default Aircraft. A copy of the Aircraft's files is included by the Flightgear project in the SourceForge FlightGear FGData repository See C172P-team Github Repository
    Add-On 1 Example Example
    Add-On 2 Example Example
    Add-On 3 Example Example
    Plib Example Example

    Obtaining Source Materials

    FlightGear related Source Materials may be hosted in a number of different services. Depending on the exact material, you may be working with files from the FlightGear Project on SourceForge, other SourceForge projects, projects from GitHub, GitLab or other SCM repository service. You may be dealing with data that originates in other Simulation Projects, or with code from supporting libraries such as Open Scene Graph.

    Quite a lot of the source materials for the flightgear application are maintained as repositories on SourceForge. Complete FlightGear SourceForge Repository List. Two of these Repositories are no longer used: FGCom and FGRun. These repositories are obsolete because their functional parts have been included within FlightGear.

    The rest are documented in the section above.

    Part 1 - Creating a Sourceforge Fork

    Part 1A - Create a Sourceforge Account, SSH Key and Verify that it works
      • Requires one personal sourceforge account
      • Requires an ssh login be setup
        • Create an SSH Key for use with Sourceforge
        • Update Sourceforge SSH Keys
        • Login to the shell with your key to make sure things are working right.
        • Logout from the shell - You won't be working there.
        • Login to Sourceforge on the web. You will be working with the web interface to sourceforge to create Forks.
    Part 1B - Create Sourceforge Forks for each Flightgear git repository you need to work in

    If you are not going to make changes to a particular repository, but only wish to do builds tracking next, you only need a clone of the official Flightgear on your local machine. You don't need to bother with creating a SourceForge Fork. You can have a mixture of local gits, some with multiple remote connections origin, upstream and possibly others, others only connected once to flightgear as origin.

    In order not to strain SourceForge resources, it's a good Idea to get rid of any forks that are not used for a while, certainly any that are not used at all for changes and experimental branches. This is especially true of resources that are large.

    Note that if you later decide to contribute to a new area, or to resume contributing, you will be able to create a fork and attach it to the local clone you previously created using the steps below.

    • Open https://sourceforge.net/projects/flightgear/
    • Log in to your sourceforge account by clicking the login button if you're logged out.
    • Hover over Me and select Profile with a right click and select open link in new window.

    If you don't see Git under personal tools in your profile page, it's because you've not set up any SourceForge Forks yet.

    Creating a Sourceforge fork is easy, Just go to the FlightGear Repo you wish to fork and click the fork button on the Left. It takes a few minutes and is pretty easy to figure out. You'll get to see the clone statement for the repo after refreshing the page after the fork is created.


    Part 2 - Create a local clone for each Sourceforge Fork

    If you already have clones of Flightgear git repos from Sourceforge, there's no need to re-do them as clones of your SourceForge Forks, they can easily be converted using the same steps you would use on a fresh clone of a personal fork.

      • create origin remote
      • create upstream remote
      • set upstream fetch to main flightgear repositories
      • create a branch for working on changes
      • checkout next
      • checkout a change branch
      • stash changes on a branch
      • push a change branch to your SourceForge fork
      • pull changes from next
      • got fetch

    Tools

    Tools for a Flightgear Developer (see also Tools of the Trade)

    From Command Line to Holding Short

    From Command Line to Holding Short. A look at what gets called when you start Flightgear from the command line until you are on the runway. This is a work in progress, somewhat stalled after Eduard Auvergne's initial work on subsystems. It needs a re-vamp to make it current and publishable.

    RTFM
    • http://wiki.flightgear.org/FlightGear_Manual
    • fgdata/doc/img Look at each image in, noting the name of the image and what the image is trying to say
    • fgdata/doc/keyboard/map.pdf Note that key bindings can be specific to an aircraft. Note that the pdf was produced from a .tex file.
    • fgdata/Docs/model-combined.eff/README.model-combined.eff Read and not What's "rembrandt" - Key terms can be pulled from this document
    • fgdata/Serial/nmeafaq.txt Garmin - Key terms can be pulled from this document. This document describes a data protocol
    • AI_doc.html
    • FGShortRef.html
    • http://flightgear.org/Docs/FlightGear-FAQ.html
    • fgdata/Docs/fschool_0.0.3.pdf
    • fgdata/Docs/index.html
    • fgdata/Docs/model-howto.html
    • and lots of others - point is you have to read them all

    Once they're read, is there a way to organize them so the result is an overview?

    Sure there is. Just write a book:

    IDEs

    Working on Configurations for Visual Studio, Visual Studio Code, Atom, Eclipse and QTCreator IDEs and other tools for working with FlightGear Data.

    The day to day work of a FlightGear Developer will include the use of a variety of software to work on various kinds of FlightGear material. The material includes Source Code written in C and C++, Scripts written in Nasal, Build procedures using CMake and in scripting languages of 3 operating Systems, Data Files representing Airports, Runways, Taxiways, Airport Markings, Navigation Beacons, Instrument Landing System Transmitters, Taxiway and Runway Lighting, Buildings, Roadways,

    The workflow for all of these has a few basic steps.

    • Get copies of the original source material
    • Establish a fork repository for your changes to the materials
    • Make a local copy of the materials
    • Change the materials
    • Check the Validity of Changes
    • Deliver changed materials to your fork
    • Request that the changes be accepted and merged with the original source materials.

    The workflows differ based on the true owners of the originating material and the materials format.

    These are the basic tasks that a developer will need to complete

    • Setting up forks of FlightGear Git Archives
    • Identifying non-git Open Source Resources for use with Flightgear and establishing forks for them
    • Downloading appropriate tools for working on the kind of files that make up the FlightGear application and it's data
    • Configuring these tools and FlightGear itself to operate in one or more modes
    • Learning the steps to use inside and outside the tools


    Figuring out how to contribute to FlightGear

    Getting things done in Flightgear


    As part of my Cockpit Building efforts, I'm also working on

    Contact

     Email Callahanp through the wiki
    

    I show up occasionally on discord, #flightgear on irc.flightgear.org and am a member of several public forums related to cockpit building.

    Callahanp (talk) 09:45, 11 November 2017 (EST)

    The Howtos

    -- Oh yeah... those...

    I'm working on these along side building my cockpit. Some of the early attempts were not that useful. My current approach is to build and document actual hardware. I hope this will be more helpful.

    Current Projects: