UPDATE: Because I needed something right away, I've created a simple shader wrapper that does the sort of thing I need. You can find it here: ShaderManager on GitHub. Note that it's designed for Objective-C / iOS, so may not be useful to everyone. If you have any suggestions for design improvements, please let me know!

Original Problem:

I'm new to using GLSL shaders. I'm familiar enough with the GLSL language and the OpenGL interface, but I'm having trouble designing a simple API through which to use shaders.

OpenGL's C interface to interact with shaders seems cumbersome. I can't seem to find any tutorials on the net that cover the API design of such things.

My question is this: does any one have a good, simple, API design or pattern to wrap the OpenGL shader program API?

Take the following simple example. Say I have one vertex shader that just emulates fixed functionality, and two fragment shaders - one for drawing smooth rectangles and one for drawing smooth circles. I have the following files:

Shader.vsh : Simple vertex shader, with the following inputs/outputs:
    -- Uniforms: mat4 Model, mat4 View, mat4 Projection
    -- Attributes: vec4 Vertex, vec2 TexCoord, vec4 Color
    -- Varying: vec4 vColor, vec2 vTexCoord

Square.fsh : Fragment shader for drawing squares based on tex coord / color
Circle.fsh : Fragment shader for drawing circles based on tex coord / color

Basic Linking

Now what is the standard way to use these? Do I link the above shaders into two OpenGL shader programs? That is: 

Shader.vsh + Square.fsh = SquareProgram
Shader.vsh + Circle.fsh = CircleProgram

Or do I instead create one big program where the fragment shaders check some conditional uniform variables and call out to a shader function to generate their result. E.g:


                    
                    

                        
                        ios
                        
                        opengl
                        
                        wrapper
                        
                        glsl
                        
                    

                    

                        
                        
                        
                        
                        
                        Edit
                        
                        
                        

                            
                        

                        
                        Report