Depth Buffering
Algorithm:
    Cast a ray from the viewpoint through each pixel to find the closest surface


    Rendering Loop:

      set depth of all pixels to ZMAX
      foreach primitive in scene
        determine pixels touched
          foreach pixel in primitive
            compute z at pixel
            if (z < depth) then
              pixel = object color
              depth = z
            endif
          endfor
        endfor
Lecture 15   Slide 12   6.837 Fall '00