OpenGL Fragment Shader

gistfile1.cpp

void InitShading(){

  //Fragment shader we want to use
  GLuint oddRowShaderId = glCreateShader(GL_FRAGMENT_SHADER);
  std::cout << "Creating the fragment shader with id " << oddRowShaderId << std::endl;

  const GLchar *source =
      "void main(){"
      "  if (mod(gl_FragCoord.y-0.5, 2.0) == 1.0){"
      "    gl_FragColor = gl_Color;"
      "  } else {"
      "    gl_FragColor = vert4(0.0, 0.0, 0.0, 1.0);"
      "  }"
      "}";

  std::cout << "Shader source:\n" << source << std::endl;

  std::cout << "Gathering shader source code" << std::endl;
  glShaderSource(oddRowShaderId, 1, &source, 0);
  
  std::cout << "Compiling the shader" << std::endl;
  glCompileShader(oddRowShaderId);
  
  std::cout << "Creating new glCreateProgram() program" << std::endl;
  GLuint shaderProgramId = glCreateProgram();    //Shader program id
  
  std::cout << "Attaching shader to the new program" << std::endl;
  glAttachShader(shaderProgramId, oddRowShaderId); //Add the fragment shader to the program
  
  std::cout << "Linking the program " << std::endl;
  glLinkProgram(shaderProgramId);                //Link the program
  
  std::cout << "Using the program for rendering" << std::endl;
  glUseProgram(shaderProgramId);                  //Start using the shader
}