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Chapter 13: Modeling with Polygons and Patches

FIGURE 13.32
The organic look for this tooth is accomplished with NURMS.

Introducing Patch Grids

Because patches have splines along their edges, a patch can be deformed in ways that a normal polygon
cannot. For example, a polygon always needs to be coplanar, meaning that if you look at it on edge, it
appears as a line. A patch doesn’t have this requirement and can actually bend, which permits greater con-
trol over the surface and makes it better for modeling things like clothes and natural objects like leaves.

Cross-Ref
Patches have many similarities to the NURBS modeling type. NURBS stands for Non-Uniform Rational B-Spline.
Coverage of NURBS is presented in Bonus Chapter 3 on the DVD. n
Another key advantage of Patch objects is that they efficiently represent the object geometry. If you examine
some mesh objects, you’ll notice that they contain a discrete vertex at the intersection of every edge at the
corner of every face. Patch grids, on the other hand, have a vertex only at the corner of every patch. Each
patch can consist of several faces. This reduction of vertices makes patches much cleaner and less cumber-
some objects to work with.

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