|void||Trim_NURBS_Surface_By_Poly (int cpcount, const float *points)|
|Inserts a polyline into the trim list and applies the trim to a surface. More...|
|const float *||points|
Inserts a polyline into the trim list and applies the trim to a surface.
cpcount - Number of valid points in points. points - Vector of u-v tuples for the coordinates of the control . (A simple N x 2 array may also be used.) Passed by reference always. length should be 2 x cpcount x sizeof(float).
These functions are not legal except when there is a valid NURBS Surface that has been opened with a call to Open_Geometry() . Trim_NURBS_Surface_By_Curve() and Trim_NURBS_Surface_By_Poly() cut away a region from a NURBS Surface. The trim region can be defined either by a polygon or NURBS curve. Such 2d trim regions are defined in u,v parametric space.
NURBS Surfaces in HOOPS effectively have a parameterization from [0..1, 0..1], for he purposes of specifying trim regions. The uvpoints (for polys) and uvcontrol_points (for curves) are in the order [u1,v1,u2,v2, ... , u(N-1),v(N-1),uN,vN].
The last point of the trim will be implicitly connected to the first to form a closed region. Trim objects are normally each interpreted as independent closed regions, but can be combined using trim collections (see Create_Trim_Collection() ). Portions of the NURBS surface that fall within that closed region are cut away or saved, depending on the operation type set in Set_Trim_Operation() . The process of trimming a NURBS surface is thus a boolean subtract.
Trim objects are prepended to the front of the trim list, meaning that trim list offset 0 is the most recently inserted.
Here's some pseudocode:
key = HC_Insert_NURBS_Surface(...) HC_Open_Gometry( key ) HC_Trim_Surface_By_Poly(...) HC_Close_Geometry()