Modifying the surface

The shape of patches are defined by the positions of their control points, which lie within an n x n network called the control point net (the value n is set on the General Page of the Patch Options dialog). This section describes how to use the tools PACE provides for managing the control point nets of individual patches. These tools support three mechanisms for doing this:

• Controlling the options used when automatically generating patch shape

• Controlling the tangency conditions along individual patch boundaries

• Interactively moving patch control points

As a general guide, the user should seek as much improvement in surface quality as possible by iteratively rebuilding the surface whilst changing the boundary curve network and global patch options. Once a stage is reached where this yields no further improvement, the user can refine the surface by interacting with individual patches, using the tools described in this section.