I was about to create a some classes to create primitives in order to help me with debugging. However, I don't know if each primitive should share its vertices. For example, a cube should not share its vertices because the normals would be inadequate for lighting and the uv coordinates wouldn't fit for a cubemap. However, for a sphere the normals would be better with shared vertices but what about the uv's? Would it work or should I not share the vertices for a sphere and instead calculate the normals as if they were shared?