GLKit Effects Constants
Overview
GLKit effects implement shaders to perform their calculations. These shaders require vertex data to be provided by your application. All of the effects provided by GLKit use a consistent set of indices to reference vertex data provided by your application. When your application enables a vertex attribute array by calling the glEnableVertexAttribArray function, or specifies the vertex attribute pointer by calling the glVertexAttribPointer function, it uses one of these constants to specify the index parameter.