For polygonal meshes that describe a closed shape (for example, a sphere), it is often wasteful to spend any time rendering the polygons whose normal vector faces away from the eye because it is known that the polygons whose normals face toward the eye will obscure those back-facing polygons. Therefore, for efficiency, it may be beneficial to employ back-face culling, which is simply the process of choosing to skip the rasterization of any polygons whose normal vector faces away from the eye.
On an IDLgrPolygon object, set the REJECT property to a value of 1 to enable back-face culling.