UnReal Engine Core documentation

Hi All,
I’ve come to the conclusion that the UnReal Engine will not allow me to add my own c++/OpenGL code to an existing development through standard mechanisms. Therefore I am forced to consider opening the code and pulling it in that way.

Is there any good documentation on the design of the Engine code itself?

Thanks in advance,

You can add C++ code by right clicking anywhere in the content brower and clicking Add C++ class

There is a custom expression node available in the material editor; although you might want to make your own .usf (unreal shader file) in order to ensure cross-compilation (HLSL only). If you only want to use OpenGL on your material , your code is only going to run into devices that only use ogl (like android).