title: OpenGL - skybox and frustum clipping
body: <p>I want to create skybox, which is just textured cube around camera. But actually i don't understand how this can work, because the camera viewing volume is frustum and the skybox is cube. According to this source: </p>
  
  <p><a href="http://www.songho.ca/opengl/gl_projectionmatrix.html" rel="nofollow">http://www.songho.ca/opengl/gl_projectionmatrix.html</a></p>
  
  <blockquote>
    <p>Note that the frustum culling (clipping) is performed in the clip
    coordinates, just before dividing by wc. The clip coordinates, xc, yc
    and zc are tested by comparing with wc. If any clip coordinate is less
    than -wc, or greater than wc, then the vertex will be discarded.</p>
  </blockquote>
  
  <p>vertexes of skybox faces should be clipped, if they are outside of frustum.
  So it looks for me that the cube should be actually a frustum and should match exactly the gl frustum faces, so my whole scene is wrapped inside of that skybox, but i am sure this is bad. Is there any way how to fill whole screen with something, that wraps whole gl frustum?</p>