For an overview about Utilities, see PEXlib Utilities.
The Utilities for Computing Geometric Normals include:
These utilities compute the geometric normal vectors of the following complex PEX output primitives Their input arguments are identical to the arguments of the corresponding output command function. The facet-data return argument is filled in with the computed geometric normal of each facet.
These utilities are augmented for PEXlib 5.2 to include the OCC form of the functions that were in PEXlib 5.1, allowing the three new PEXlib 5.2 data models to be used with these primitives. In addition, functions using the OCC form are provided for the new primitives. The non-OCC versions do not exist for these new primitives. Therefore, the functions appearing in PEXlib 5.1 have OCC counterparts specified on the same page.
A new "handedness" argument is added to the OCC forms of the functions for PEXlib 5.2. This argument allows you to generate normals for imported data that assumed a left-handed coordinate system, instead of needing to "flip" the normals yourself after they are generated. The non-OCC versions of the functions do not have the handedness argument and assume a right-handed coordinate system.
Use caution when using these utilities with fill areas that may possibly be concave, since it is possible to generate normals that point opposite to the intended direction if a concave portion of the fill area is used to generate the normal. In some cases, it may be possible to present the fill area vertices in a different order to obtain the intended result.