Can someone give me a way to find the normal for each primitive using my class structure. My fragmented structure:

Object: holds an array of verts and an array of primitives that make up object.

Primitive: holds indices that make up this primitive.

VERTEX: x, y, z coordinates

I've been coding for quite awhile today and i just can't think how to get this w/ my class structure. I'd like to have a method in my Primitive class that calculates the normal for that particular primitive, it it possible to do so with just indices and no verts? Ideas and suggestionns please!!??

Thanks

Frank