When importing models to a game engine, you may notice a difference in vertex count. Figure 1-9 shows three spheres with 48 tris. The first sphere is smoothed where vertices are shared between multiple faces. The middle sphere has hard edges, so only vertices on co-planar faces can be shared. The last sphere is smoothed but has been unwrapped. Because the same vertex cannot exist in multiple places on the unwrap texture, vertex numbers are also higher than the smooth sphere, with no mapping coordinates.