If I don't want to use IBL and just want to use skybox, how should I modify the code
If I don't want to use IBL and just want to use skybox, how should I modify the code
If you mean a normal cubemap skybox (6 textures) then the engine currently doesn't have that, I think its better do it myself since the renderer code is a bit different then the one in the repository and I'm updating it soon anyway.
If you really want to modify the code, you will have to make your own "SkyboxCube" class thats loads the shader and the textures and renderers them...etc and then use it from the renderer class in the "Renderer::RenderScene" function, though I don't encourage you to do that :)
If I want to import the model from the outside, the model itself has texture mapping, and I changed the model.cpp and mesh.cpp, I'd like to know render.cpp how should be changed