I have a very large OpenGL application that doesn't use shaders. We use almost all the non-shader gl functionality in this application. We recently found the need to add some functionality for which we will need to add shaders.
My question: if I add shaders do I have to recreate all the functionality I already have (it's a lot!) just to be able to add one more piece of functionality? It feels almost like rewriting the entire code again. For example, lighting and texturing.