The texture may be defined along with the object as discussed earlier, or it may be declared and assigned a name. Review the section on textures if the texture definitions are confusing. Triangles Triangles are also fairly simple objects, constructed by listing the three vertices of the triangle, and its texture. The triangle vertices are listed as V1, V2, and V3 each one is an X, Y, Z coordinate. Smoothed Triangles Smoothed triangles are just like regular triangles, except that the surface normal for each of the three vertexes is used to determine the surface normal across the triangle by linear interpolation.
Smoothed triangles yield curved looking objects and have nice reflections.
Infinite Planes Useful for things like desert floors, backgrounds, skies etc, the infinite plane is pretty easy to use. The center of the plane is just any point on the plane such that the point combined with the surface normal define the equation for the plane. As with triangles, planes are double sided. Rings are simply an infinite plane cut into a washer shaped ring, infinitely thing just like a plane. A ring only requires two more pieces of information than an infinite plane does, an inner and outer radius.