Rebuild Options

When (All Patches) is selected in the Patch ID box, each time the Apply button on the Patch Options dialog is clicked, the entire surface is rebuilt. These checkboxes give the user the ability to preserve certain characteristics of the old surface in the rebuilt surface.

If the user has made changes to individual patches, they are likely to want to preserve these in the rebuilt surface. For example, the surface must be rebuilt in order to change the patch boundary topology (for example, adding or removing a patch boundaries by introducing or removing an active curve). Checking Preserve patch settings preserves individual patch options that differ from the default settings. Checking Preserve patch geometry preserves manual changes that have been made to control point positions. The settings and geometry cannot be preserved for the patches that are directly affected by the addition or removal of boundaries.

Building a surface involves two stages. First, the network of patch boundaries is found from the intersecting network of active curves. Each patch boundary curve approximates the shape of the active curve segment that it corresponds to - the exact shape of the boundary curve is determined by the settings used when the surface was last built, particularly whether or not data points are enabled for building the surface. Sometimes it is desirable to rebuild the internal geometry of all the patches without rebuilding the patch boundary curves. This is achieved by checking the Preserve boundary network box.

Note that it is not possible to check all three boxes, as this would mean that nothing about the current surface would be changed. These options are not available for rebuilding individual patches.