Managing Game Code in Unreal Engine | Unreal Engine 5.2 Documentation

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User Project Files

Unreal Engine (UE) recognizes two different types of projects: native and foreign.

Native Projects

Native projects are projects that exist within the same root directory as the engine that was used to create them. As a result, they have the following directory structure:


.
└── ROOT/
    ├── Engine/
    │   ├── Binaries/
    │   ├── Build/
    │   ├── Config/
    │   └── ...
    ├── PROJECT1/
    │   ├── Binaries/
    │   ├── Build/
    │   ├── Config/
    │   ├── ...
    │   └── PROJECT1.uproject
    ├── PROJECT2/
    │   ├── Binaries/
    │   ├── Build/
    │   ├── Config/
    │   ├── ...
    │   └── PROJECT2.uproject
    ├── ...
    ├── Default.uprojectdirs
    ├── GenerateProjectFiles.bat
    └── ...

With this structure PROJECT1 and PROJECT2 are both native projects. Projects with this directory structure do not require any extra configuration in order to determine which editor to use, these projects will automatically detect the editor that is built within the root directory. This is true whether you are using a source build or a binary build of UE.

Projects can be put into either the root folder, or any subfolder that has been defined in Default.uprojectdirs (for example, ROOT/Games). The .uprojectdirs file is a helper file that directs the engine to discover projects in subdirectories of ROOT. You can have multiple .uprojectdirs files in the same ROOT directory. These files are not required to be named Default.uprojectdirs, they can have any name you wish as long as the file extension is .uprojectdirs.

Foreign Projects

Foreign projects are those where your project directory is in some location other than under the same root directory as the engine directory. An example of this would be:


├── UE/
│   ├── Engine/
│   │   ├── Binaries
│   │   ├── Build
│   │   ├── Config
│   │   └── ...
│   ├── ...
│   ├── Default.uprojectdirs
│   ├── GenerateProjectFiles.bat
│   └── ...
├── PROJECT1/
│   ├── Binaries
│   ├── Build
│   ├── Config
│   ├── ...
│   └── PROJECT1.uproject
├── PROJECT2/
│   ├── Binaries
│   ├── Build
│   ├── Config
│   ├── ...
│   └── PROJECT2.uproject
└── ...

When a foreign project is created from a launcher (binary) build, the EngineAssociation field in its .uproject file is set to the version number of the launcher engine that was used to create it. In case you created the project from a source-built version of the Unreal Editor it will put in the Globally Unique Identifier (GUID) of that editor. This GUID is automatically generated and saved on your computer the first time you launch your source-built editor. The locations where these are stored on different operating systems are:

Windows:
- Registry: Computer\HKEY_CURRENT_USER\SOFTWARE\Epic Games\Unreal Engine\Builds
Mac:
- File: ~Library/Application Support/Epic/UnrealEngine/Install.ini
Linux:
- File: ` ~/.config/Epic/UnrealEngine/Install.ini`

For example, say PROJECT1 was created from a source-built version of the Unreal Editor, then the PROJECT1.uproject file contains something of the form:


{
	"FileVersion": 3,
	"EngineAssociation": "{5FFE8984-EA6F-49EC-859E-6CB8C10FE54D}",
	"Category": "",
	"Description": "",
	"Modules": [
		...
	],
	"Plugins": [
		...
	],
	"TargetPlatforms": [
		...
	]
}

where 5FFE8984-EA6F-49EC-859E-6CB8C10FE54D is the GUID associated with the source-built version of the Unreal Editor used to create the project. In contrast, suppose PROJECT2 was created from a UE 5.1 launcher version of the Unreal Editor, then the PROJECT2.uproject file contains:


{
	"FileVersion": 3,
	"EngineAssociation": "5.1",
	"Category": "",
	"Description": "",
	"Modules": [
		...
	],
	"Plugins": [
		...
	],
	"TargetPlatforms": [
		...
	]
}

Change a Project's Unreal Engine Version

You can change the Unreal Engine version that is used to open a project by first right clicking on the project's .uproject file and choosing Switch Unreal Engine version... This will bring up a dialogue box with a dropdown menu where you can select the version of UE with which to open this project. When this dialogue box first appears, it will display the current Unreal Engine distribution that is set to open this project. Launcher builds in this dropdown menu are identified by their version number (for example, 4.27 or 5.0) and source builds are identified as Binary build or Source build followed by the build's directory. This directory is the value associated with the GUID key associated with the EngineAssociation field in the .uproject file. To switch the engine version, select your desired Unreal Engine distribution from the dropdown menu. The system will then regenerate project files to implement this change.

Adding Code to Projects

C++ Class Wizard

The C++ Class Wizard provides a fast and easy way to add native C++ code classes into your project for you to extend with your own functionality, if you wish. This converts a content-only project into a code project. You can access the C++ Class Wizard and create a new C++ class by following these steps:

Check Setting Up Visual Studio to ensure that you have a compatible version of Visual Studio installed before proceeding. For information about the correct version of Xcode, refer to the Unreal Engine Release Notes.

In the main editor, select Tools > New C++ Class...
The C++ Class Wizard will appear and show Common Classes by default. If you do not see the class you are looking for, you can view the entire Class hierarchy listing by selecting All Classes.

Common Classes All Classes
Choose the Class you want to add. For the purposes of this demonstration, we will choose to create a new Actor Class. Select the Actor Class, then click Next >.
You will then be prompted to enter a Name for your new Class. Do so, then click Create Class. This will create the header (.h) and source (.cpp) files.

Class names can only contain alphanumeric characters and cannot contain spaces. The field will notify you if you enter an invalid name.
In Unreal Engine, Live Coding is now enabled by default. A Live Coding window will appear and compile the new class files that were created.
The code will immediately open in Visual Studio, ready for editing.

The code will immediately open in Xcode, ready for editing.


Common Classes	All Classes

Development Environment

Code files can be created through Visual Studio and added to the game project through the Solution Explorer in the usual manner. You can also add code files to the appropriate folders outside of Visual Studio and rebuild the solution and project files automatically. This makes it easy to add lots of files quickly through the operating system UI, and also makes working on teams easier as the solution and project files do not need to be synced between members of the team. Each person can just sync the code files and rebuild the project files locally.

Code files can be created through Xcode and added to the game project through the Project Navigator in the usual manner. You can also add code files to the appropriate folders outside of Xcode and rebuild the project file automatically. This makes it easy to add lots of files quickly through the operating system UI, and also makes working on teams easier as the solution and project files do not need to be synced between members of the team. Each person can just sync the code files and rebuild the project files locally.

Opening Projects in the Development Environment

If your project is already open in the Unreal Editor, you can easily open it in Visual Studio by selecting Open Visual Studio from the Tools menu.

You can also open the project in Visual Studio through Windows Explorer or Visual Studio's File > Open > Project/Solution.

If your project is inside the UE root directory:

* Open the UE5.sln Visual Studio solution located in the UE root directory.

If your project is outside of the UE root directory:

* Open the PROJECT_NAME.sln Visual Studio solution located in the root of the project's directory.

If your project is already open in the editor, you can easily open it in Xcode by selecting Open in Xcode from the File menu.

You can also open the project in Xcode through Finder or Xcode's File > Open.

* Open the PROJECT_NAME.xcodeproj Xcode project located in the root of the project's directory.

Generating Project Files

The project files are considered intermediate files - located in PROJECT_DIRECTORY\Intermediate\ProjectFiles. This means if you delete your Intermediate folder, you must regenerate the project files.

.uproject files

If your project is outside of the UE root directory:

1. Navigate to the location of PROJECT_NAME.uproject in Windows Explorer.

1. Ensure that PROJECT_NAME.uproject is highlighted by Left-clicking once. Now, Right-click on the PROJECT_NAME.uproject file and select Generate Visual Studio Files.

1. UnrealBuildTool updates the project files and the solution, including generating Intellisense data.

1. Open the PROJECT_NAME.sln Visual Studio solution located in the root of the project's directory to view the game project in Visual Studio.

1. Navigate to the location of PROJECT_NAME.uproject in Finder.

1. Right-click on the PROJECT_NAME.uproject file and select Generate Xcode Files.

1. UnrealBuildTool updates the project

1. Open the PROJECT_NAME.xcodeproj Xcode project located in the root of the project's directory to view the game project in Xcode.