title: How to know the plane size in units?
body: <p>Well the thing is, that I wan't to picture mazes with a different width and height. I'm drawing them in units and my question is, how can I get the plane viewable dimensions in units that I would know how deep inside the screen I would have to draw my maze in order it would be fully seeable. For perspective view I use "::gluPerspective(45.0f, (GLfloat)width / (GLfloat)height, 1.0f, 100.0f);" </p>
  
  <p><img src="https://i.stack.imgur.com/aEwwS.png" alt="perspective"></p>
  
  <p>For example how I get the near plane dimensions(width and height) in OpenGL units or the far plane or any plane between those planes. If I want to picture something entirely seeable I need to know the plane dimensions in OpenGL units or is there another way?</p>