August 7, 2022 8 min to read

A DIY Flight Simulator Tutorial(4)

A DIY(Do It Yourself) Flight Simultor Tutorial

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아래 내용은 Epic Games 에서 제공하는 앙투아네트 프로젝트: 차세대 비행 시뮬레이터 제작 툴 포스트 내용을 주로 다루고 있습니다.

JSBSim for Unreal - UEReferenceApp

Introduction

Welcome to the UE Reference Application for JSBSim.

This application has initially be created by the Simulation Team at Epic Games in the context of “Antoinette Project” This project was made to illustrate that Unreal Engine 5 with its double precision and graphic capabilities could be used for serious flight simulations. For that purpose, we wrote a plugin for UE5 wrapping around the JSBSim Flight Dynamic model to leverage its capabilities and fly and Aircraft inside an Unreal Engine environment.

We decided to share this sample with the community as an open source project, hosted on JSBSim’s Github. This reference application is voluntarily simple to make sure it’s easy to understand.

But we are sure that the aviation community will like it and take inspiration from it. We hope that some aviation geeks will fork it and create wonderful flight sims from this starting point!

Enjoy, and Simulation for the win!

Building the application

1. Install Unreal Engine 5.x

The procedure to install Unreal Engine is described here : https://www.unrealengine.com/en-US/download For hobbyists, the standard license applies, and is 100% free!

Note: In order to build C++ plugins for Unreal, you’ll need at least Visual Studio 2019 v16.4.3 toolchain (14.24.28315) and Windows 10 SDK (10.0.18362.0). (Visual Studio Community can also be used)

Important Note for Visual Studio 2022 users As of 05/12/2022, Epic Games warns that some latests updates to VS2022 toolchain might break the build of UE applications. These issues will be addressed in a further UE hotfix release. While waiting for theses fixes, the recommended approach is to use the VS2019 Toolchain to build the application. You can still use VS2022 as an IDE, and don’t need to have VS2019 IDE installed. Just its toolchain.

From the Visual Studio installer, make sure you have these components installed:
- Windows 10 SDK (10.0.18362.0)
- MSVC v142 - VS2019 C++ x64/x86 build tools (v14.29-16.11)
Force Unreal Build tool to produce VS2019 projects
- Create a file named "BuildConfiguration.xml" in %APPDATA%\Unreal Engine\UnrealBuildTool
  (ex: C:\Users\JohnDoe\AppData\Roaming\Unreal Engine\UnrealBuildTool)
- Edit the file so that he looks like this one with a CompilerVersion block :

<?xml version="1.0" encoding="utf-8" ?> 
<Configuration xmlns="https://www.unrealengine.com/BuildConfiguration">
<WindowsPlatform>
    <CompilerVersion>14.29.30136</CompilerVersion>
</WindowsPlatform> </Configuration> You can learn more about this option file [here](https://docs.unrealengine.com/4.27/en-US/ProductionPipelines/BuildTools/UnrealBuildTool/BuildConfiguration/)...

You need to do these changes before building/opening the UEReferenceApp project (step 4 below). If you already tried a build with VS2022, you’ll need to clean all intermediare project files, by running the CleanProject.bat file in the UEReferenceApp root folder.

Thanks to Ali M. and James S. for reporting this special case issue.

It is also recommended to set up Visual Studio for Unreal using the following procedures https://docs.unrealengine.com/5.0/en-US/setting-up-visual-studio-development-environment-for-cplusplus-projects-in-unreal-engine/ https://docs.unrealengine.com/5.0/en-US/using-the-unrealvs-extension-for-unreal-engine-cplusplus-projects/

2. Build JSBSim as Dynamic libraries and stage Model files

Unreal Engine requires that one plugin contains all its needed files in its sub-folders. This application contains a Plugins/JSBSimFlightDynamicsModel folder containing the JSBSim files. In some of these subfolders, one has to place

The JSBSim libraries, compiled as dynamic libs
The aircrafts/engine/systems definition files.

When the UE application will be packaged, the resources will be copied along with the executable, and the application dynamically linked against the libs transparently.

To make this process easier, there is a new solution named JSBSimForUnreal.sln at the root of JSBSim repo.

Simply open and build this solution with VS2019, in Release, (and in Debug if you want too, but this is not mandatory)
It will take care of making a clean build, and copy all needed files at the right location
- All libs and headers in UnrealEngine\Plugins\JSBSimFlightDynamicsModel\Source\ThirdParty\JSBSim
- All resource files (aircrafts/engines/systems) in UnrealEngine\Plugins\JSBSimFlightDynamicsModel\Resources\JSBSim

3. [Optional] - Download HD resources In order to keep the JSBSim repository lightweight, this application contains low quality resources. If you would like to use better looking content, you can download HQ aircraft model, HD textures and non-flat terrain here: High Definition content pack (330 MB)

Simply extract this archive and copy/paste the content folder into the one of UEReferenceApp, overriding the existing files.

4. Build/Open the Unreal Project

Option 1 : Simply double click on the UnrealEngine\UEReferenceApp.uproject file. It will open a popup complaining about missing modules (UEReferenceApp, JSBSimFlightDynamicsModel, JSBSimFlightDynamicsModelEditor). Answer Yes, and the build will be triggered as a background task.

Once done, the UE Editor will open. If you get an error message, build manually using Option 2 below.

Option 2 : Generate a project solution, and build it using Visual Studio. Right click on the UnrealEngine\UEReferenceApp.uproject A contextual menu will appear. Select “Generate Visual Studio project files” After a short time, a new solution file UEReferenceApp.sln will appear beside the uproject file. Open it, and “Build Startup project” from the UnrealVS Extension bar.

Note that this Option 2 is the recommended way to edit the plugin code, and then you can run and debug it like any other VS application.

Learning more about Unreal Engine

You can find many free learning resources on Unreal Engine Developper Community portal : Getting Started Library of Learning Courses

Still in the context of “Antoinette Project” we wrote a more advanced tutorial to leverage these developments in an even better looking application. You can find a very complete description here: https://dev.epicgames.com/community/learning/tutorials/mmL/a-diy-flight-simulator-tutorial

Key Mappings

Gamepad Layout

Flight Commands

Application

Environment

Command	Shortcut
Time of day - Increase	PAGE DOWN
Time of day - Decrease	END
Time of day - Dawn Preset	INSERT
Time of day - Noon Preset	HOME
Time of day - Dusk Preset	PAGE UP

Update: version 1.01

The JSBSim interface is now updated to have a pseudo fixed rate of 120hz, independent of game framerate. This is done by stepping the sim x times per game frame (hence pseudo). It’s best to set the game engine to a fixed rate, otherwise fluctuating framerates could introduce instabilities in JSBsim. (Tip: Find the min of your average framerate and use that as the game fixed framerate.)
Added new functions/blueprint nodes to access any JSBSim property. This is especially useful to get and set any command value. See next section for usage.
Reduced the project/repo size by lowering aircraft model quality and removed unused assets. (full quality aircraft model in HD download link above)

Extended Commands and Properties

JSBSim has a Property Manager to keep track of all properties, settings, and commands.
New functions and blueprint nodes were added to the UE plugin to access this Property Manager, as a general command console interface to JSBSim.
Example of usage: The ah1s helicopter model loads new controls at runtime. Using the new functions we can access it’s controls without having to hardcode every usecase into the UE plugin.

Notes…

As you’ll see in the aircraft animation blueprint comments, we used an aircraft model from the UE Marketplace which bones were not really well aligned with the rotation axes of moving parts. While it could (had has been) solved by using 1D Blend Space, a better way to do it would have to align the bones correctly, and just drive the locations by angles. But it would have required the aircraft 3D model sources that we did not have.
The aircraft lights have been made only for illustration purpose. The cone angle logic is approximate and the blinking frequencies/patterns are not the real ones. (We don’t want to freak out the purists ;-) )
The Primary Flight Display is very simple too. A pitch indicator would help too…
The terrain is a sample terrain. One might use other terrain sources, as long as the georeferencing is correct!
Gamepad support is limited, but can easily be improved in the Input Settings
Multiple instances of JSBSim components/aircrafts currently does not work. You can only run one aircraft simulation at a time.