   Creating a shader framework
  Hi,I'm nearing the completion of my fixed-function engine in OpenGL, and I'm starting to add a Cg shader framework, and I have some questions.It's currently designed like this:MODEL class - contains one Mesh object, position, rotation, etcMESH class - contains a vector of mesh Subset objects, and functions for loading from proprietary file formatSUBSET class - contains vertex/face array, one Material objectMATERIAL class - contains one Texture object, one Shader object, UV coords, colours, etcSHADER class - contains CGeffect object, functions to get passes, set current technique and set parametersMaterials are loaded from a proprietary format, containing the shader filename and a list of parameters to apply. The rendering steps are as follows:- For each Model:   - For each mesh subset: - Apply material - Apply shader parameters - For each shader pass:    - Set pass    - Render subset    - Get next passHow can I allow for post-effect shaders? I'm trying to figure out the rendering steps to allow for both post-effects per model (i.e. glow), as well as full scene effects (i.e. cel shading), but I'm unsure as to how I should design it. I know I need to add support for render-to-texture (framebugger in OGL?)Could someone give me a brief bullet point list of the rendering steps to perform?   