The following illustration shows a camera and the frustum with the near plane and the far plane. The light grey objects are outside the frustum, the black objects are inside the frustum, and the dark grey objects are partially inside the frustum.
Rendering objects that are outside the frustum would be a waste of performance. Even triangles that are not on the screen because objects are partially outside the frustum should better not be rendered.
Culling is the process of identifying what is totally or partially inside the frustum and getting rid of what is not inside (in the illustration, the light grey objects and parts of the dark grey objects). Papervision3D includes culling and does not render objects and triangles that are outside the frustum, which increases performance. Before we examine how we can tell Papervision3D to apply culling, let's see which types of culling are generally used in 3D computer graphics.
