How can I modify core Unreal Engine 4 files?

If I have a current project how am I able to modify core Unreal Engine 4 files such as those that translate the Unreal Engine library to iOS or Windows or Steam such as these files documented in the following links:

and the Windows, Mac, iOS variants that adapt and implement the GenericPlatform.

In source code which you can pull from git hub, made github account and add it in to unreal profile. Most optimal way is to make plugin, but if you want to edit such core elements as platform support i think only way is to edit source code direcly.

Yep I have the source code downloaded so do I just add the modified files to the Visual Studio code base? Or the Unreal Editor? Or do I do something to specify it during deployment to Android or iOS etc?

Install 2nd copy of UE4 (2nd sourcecode) and modify as you like, it all gonna be used inside packaged game, as for platfrom that depends what portion of the game you operate with. If you make some good modifications you try to pull request so it gonna be included in main source :slight_smile: You might also conider making plugin:

but as i said the you mgiht not able to modify any platfrom stuff from it… but i’m no sure wha you planing to do, maybe theres other way for thing you why to do

So what exactly you trying o do?

Mix android native GUI elements with the unreal engine 3D rendering. Basically have a sidebar that is native android GUI (which I can easily do through the JNI) and then have a Android View that is then used by Unreal to draw on. However I am unable to find where Unreal translates the local OS drawing methods to a standard Unreal engine can use (I know of Android Window but thats as far as i got).

Basically I want an Android View to act as the full screen as far as Unreal is concerned so I can then use the rest for native gui widgets.

Then why dont you just modify Java portion of code? You can find it in engine/build/android/java and implement you ui stuff there. Also you dont need UE4 source code for that as java code is ala avable in prebuild version

Because as I understand it Unreal Engine expects to get a native window.

But cant you implement ui from java part?

Yes that is my understanding but what I am concerned about is how do I modify the NativeWindow that android gets? I assume by modifying the java code and maybe AndroidWindow.cpp. That is what my question is about is how do I access those files in the project, change them, and recompile them?

Ok I figured it out

When you build your program in the Unreal Editor it uses the library files located in your Program Files directory. (You can find them by searching in the Unreal Engine app folder). From this you can modify these files and run the program to add java code or modify core files. Note some of these files may be in the project build file, do not modify these, as they will be overwritten with copies from the Program Files folder.

Does anyone know how to keep it project local, so it doesn’t modify every project when you build? (e.g import them into the project and use local copies?)

This thread is good though has some dead links it mentions the file removing problem as well as using a plugin to load java code: Android Java Libraries in UE4 Game (OUYA SDK, Google Play Game Services, etc.) - Mobile - Epic Developer Community Forums

I was trying to modify ConstraintTypes.h and even if I add a new blank line I am getting this:

Error C4430 missing type specifier - int assumed. Note: C++ does not support default-int UE_4.18\Engine\Source\Runtime\Engine\Classes\PhysicsEngine\ConstraintTypes.h 95

I am trying to modify the source to allow for a custom linear constraint axis. Any ideas why this is happening?