Controls: Drag with the mouse to move the scene; use the mouse wheel to move the camera forward and back.

This demo contains a wireframe view volume of a perspective projection and two rows of spheres. Note that initially, the spheres approach the center of the screen as their depth increases. As you move the scene with your mouse, you will see how the spheres are placed in relation to the projected view volume. (Note that the view volume shown is smaller than the one that results by the scene's actual projection, in order to show the effect better.) Some of the spheres would be clipped out by the wireframe volume.