title: GLSL Problem: Multiple shaders in one program
body: <p>I must have misunderstood something with shaders:</p>
  
  <p>I thought that as you can attach multiple shaders to one program, you'd be able to simply attach more than one fragment shader, as an example: A crate texture rendered with a color modulation <strong>and</strong> refraction.</p>
  
  <p>But apparently this is not the case, as you can have only one main function per program.</p>
  
  <ul>
  <li>How can I work around the main function limit and allow for any dynamic combination of multiple fragment shaders which are in the same program and called after each other?</li>
  </ul>