How to Edit Engine Source code?

I am trying to edit some internal classes in the engine but none of my changes are being compiled. I even tried typing random syntax errors and I still can’t get the engine to fail to compile (I tried a clean and make and everything). I assume this is because somewhere the makefile is set to ignore changes to the engine code? Can someone please point me in the right direction?

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Sanity checks:

Did you…

  • check the source code out from Github?
  • compile the source code by following the instructions on Github (including running Setup and GenerateProjectFiles)?
  • run the version of the engine that you compiled?
  • quit the running editor, then recompile changes you made to the engine source code, then start the engine that you compiled?

As a side note, what Operating System are you on?

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Hi thanks for the response.

I’m running on windows 10, UE4.14.3. New to UE4 but experienced with c++. I didn’t know I needed to check the source code out from Github in order to modify the engine code. Is this not something that is done via the epic games launcher when you download the engine and create a c++ project? I am able to see all of the source code in addition to my code, so I assumed that meant I had and could therefore modify the source code… Thanks

Hi Ian,

The version of the Engine that is installed by the Launcher is a pre-compiled binary version of the Engine. The source code is included there for reference only, and the only thing that is actually being compiled in Visual Studio when you perform a build is your project code.

If you want to be able to actually make changes to Engine source code, as CleanCut mentioned, you will need to download the source code from GitHub and build the Engine yourself. When you have built the Engine from source code, any subsequent edits that you make to the source code will result in those changes being built into the Engine.

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Thanks guys! I’ll go ahead and get the source from github.