View source for Create Custom engine classes for your game module

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== Introduction ==

Creating, custom Engine classes is actually very easy, and there is not much work needed.
Why would you want to create custom Engine class ?
It's useful, when you need to initialize some data before game or editor will be loaded, during engine initialization, so that data will be accessible after game starts.

== Adding Classes ==
To get started you will need to add two new classes to your project. Note the "U" prefix, which is required for any non-Actor UCLASS. An actor uses "A":

<code>
<syntaxhighlight lang="cpp">
#include "Engine.h"
#include "YourGameEngine.generated.h"

UCLASS()
class UYourGameEngine : public UGameEngine
{
	GENERATED_BODY()
}
</syntaxhighlight>
</code>

and 

<code>
<syntaxhighlight lang="cpp">
#include "UnrealEd.h"
#include "YourGameEditorEngine.generated.h"

UCLASS()
class UYourGameEditorEngine : public UUnrealEdEngine
{
	GENERATED_BODY()
}
</syntaxhighlight>
</code>

Along with standard blank implementation in CPP files.

== Add UnrealEd dependency  ==
In your Build.cs file, you will find PublicDependencyModuleNames.
Add UnrealEd in it, like this:

<code>
<syntaxhighlight lang="csharp">
PublicDependencyModuleNames.AddRange(
    new string[] { 
        "Core", 
        "CoreUObject", 
        "Engine", 
        "InputCore", 
        "UnrealEd"
    });
 
</syntaxhighlight>
</code>

== Edit DefaultEngine.ini ==

Now you need to edit DefaultEngine.ini in your project config folder. Open file and add these lines:

<code>
[/Script/Engine.Engine]<br />
GameEngine=/Script/YourModuleName.YourGameEngine<br />
EditorEngine=/Script/UnrealEd.EditorEngine<br />
UnrealEdEngine=/Script/YourModuleName.YourGameEditorEngine<br />
</code>

That is it! Now when you compile and run you project, new classes will be used.

If you're creating a custom editor engine, there are some more set-ups that need to be done to ensure a proper building of both game and editor. Refer to https://answers.unrealengine.com/questions/41509/extending-editor-engine.html for it.

== UE4 Answer Hub Related posts ==

== Extending the editor engine ==
https://answers.unrealengine.com/questions/41509/extending-editor-engine.html

== How to Include files from another module ==
https://answers.unrealengine.com/questions/54681/how-to-include-files-from-another-module.html

== Linking error when exporting component ==
https://answers.unrealengine.com/questions/31640/linking-error-when-exporting-component.html

== How can I set up multiple modules so that they can interact? (theoretical explanation)==
https://answers.unrealengine.com/questions/39838/classinterface-multiple-modules-confusion.html



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