title: OpenGL glMatrixMode help
body: <p>I'm starting to work a little on OpenGL stuff, and I'm seeing a lot of examples that make calls to the <code>glMatrixMode</code> function. </p>
  
  <p>From what I've gathered, setting this to either GL_MODELVIEW or GL_PROJECTION (etc) will activate that specific transformation matrix and all subsequent calls to matrix transformation functions (glTranslatef, glPushMatrix, glLoadIdentity, glLoadMatrix etc) will affect the active matrix only.</p>
  
  <p>What I don't get is why are there 3 (4 in some cases) different matrices?  Which one should I use? (I'm probably going to get a lot of "Use Shaders", but I can't.  Limited by school...) When should I switch and activate a different matrix?  What is the benefit of utilizing all of them as opposed to only using one?</p>
  
  <p>Thanks for any help :)</p>