Ray-Casting
Algorithm:
    Cast a ray from the viewpoint through each pixel to find the closest surface


    Rendering Loop:

      foreach pixel in image
        compute ray for pixel
        set depth = ZMAX;
        foreach primitive in scene
          if (ray intersects primitive) then
            if (distance < depth) then
              pixel = object color
              depth = distance to object
            endif
          endif
        endfor
      endfor
Lecture 15   Slide 9   6.837 Fall '00