FlowVis/shader.h

#ifndef _SHADER_HPP_
#define _SHADER_HPP_

#include <GLEW/GLEW.h>
#include <iostream>
#include <fstream>
#include <string>

using std::string;
using std::cerr;
using std::cout;
using std::endl;

// This is a very simple shader class

class Shader
{
public:

        Shader(const string &path);

        Shader(const string &path, bool geometryShader, GLenum inputType, 
                GLenum outputType, GLint maxOutVertices);

        ~Shader();

        // Bind the shader to the OGL state-machine
        void bind() const
        {
                glUseProgram(_program);
        }

        // Unbind the shader
        void unbind() const
        {
                glUseProgram(0);
        }

        // Query the location of a vertex attribute inside the shader.
        GLint get_attrib_location(const std::string &name) const
        {
                return glGetAttribLocation(_program, name.c_str());
        }

        // Query the location of a uniform variable inside the shader.
        GLint get_uniform_location(const std::string &name) const
        {
                return glGetUniformLocation(_program, name.c_str());
        }

        // Query OpenGL errors and print error messages to STDERR.
        static void get_errors(void);

        // Define the name of the variable inside the shader which represents the final color for each fragment.
        //void bind_frag_data_location(const std::string &name)
        //{
        //      if(_program > 0)
        //      {
        //              glBindFragDataLocation(_program, 0, name.c_str() );
        //              link();
        //      }
        //}

        // A little cast helper.
        // With this you can simply do "if (shader) {...}" to test if a
        // shader has been compiled successfully.
        operator bool ()
        {
                return _success;
        }

private:

        bool _success;

        GLuint _vertex_shader;
        GLuint _geometry_shader;
        GLuint _fragment_shader;
        GLuint _program;

        bool init(const string &path, bool geometryShader, GLenum inputType, 
                GLenum outputType, GLint maxOutVertices);

        GLuint compile(GLenum type, const string &source);
        void link (bool geometryShader, GLenum inputType, 
                GLenum outputType, GLint maxOutVertices);

        void shader_log(GLuint shader);
        void program_log(GLuint program);

        bool file_exists(const string &filename);

        string read_file(const string &filename);
};

#endif //#ifndef _SHADER_HPP_