ai wrote:Well backface culling, or 'normals' as it is also called, need to point in the same direction, outward. If it points inward the faces could be invisible.
Right, so your system doesn't have to draw those. It only draws the faces that are facing the camera, so you don't want to have so many of these that it has to draw twice as much area as the model takes up on your screen, because it has so many hidden surfaces that are just going to waste anyway.
One can also delete the faces that are not visible or hidden within the model.
Right, unless parts of that face are in plain sight. Then to get rid of the hidden surface area you have to add more geometry than just the one face.