PEXOCCGeoNormFillAreaSet Utility

Synopsis

 
   int PEXOCCGeoNormFillAreaSet(
       PEXOCC context,
       unsigned int count,
       PEXPointer occ_facet_data,
       PEXListOfVertexData *occ_vertex_data,
       int handedness
   )

 
   int PEXGeoNormFillAreaSet(
       unsigned int facet_attributes,
       unsigned int vertex_attributes,
       int color_type,
       unsigned int count,
       PEXFacetData *facet_data,
       PEXListOfVertex *vertex_lists
   )

Arguments

context: An OC context returned by a successful PEXCreateOCC call.
facet_attributes (OCC): A mask indicating the facet attributes provided. It should contain the bit PEXGANormal.
vertex_attributes (OCC): A mask indicating the vertex attributes provided.
color_type (OCC): The type of color data provided.
facet_fp_data_count (OCC): The number of optional floating-point numbers for each facet.
surface_vertex_fp_data_count (OCC): The number of optional floating-point numbers for each vertex.
count: The number of fill areas in the set.
occ_facet_data: A pointer to facet data. This function adds the geometric normal to this data. See Facet / Vertex Data Formats.
facet_data: An array of facet data. This function adds the geometric normal to this data.
occ_vertex_data: A pointer to the list of vertex arrays defining each contour of the fill area set. See Facet / Vertex Data Formats.
vertex_lists: A pointer to the list of vertex arrays defining each contour of the fill area set.
data_model (OCC): Specifies the data model used to represent the geometric data.
data_model_specs (OCC): Offset and size data for the PEXDataStride or PEXDataUnpacked data models.
handedness: Orientation of the coordinate system assumed by the vertex data (PEXVertexOrderRightHand, PEXVertexOrderLeftHand).

Returns

Zero if successful; otherwise, one of the following:

PEXBadPrimitive: A normal cannot be computed because all fill areas in the set are degenerate or because the vertices of all the fill areas are colinear.

Description

Invoke PEXOCCGeoNormFillAreaSet to compute the geometric normal of a fill area set and store it in the specified facet data.

The normal is computed by finding the first three non- colinear points in a fill area of the set, beginning with the first fill area and searching until three such points are found in a single fill area. Two vectors are formed from these points: one vector from the first point to the second point, and one vector from the first point to the third point. The geometric normal returned is the normalized cross product of those two vectors.

The three points, A, B, and C are selected as follows. Point A is the first point in the first list of vertices. Point B is the next point in that same list that is not coincident with A. Point C is the next point in that same list that is not colinear with A and B. If it is not possible to find three such points in the first list, then the rest of the lists are searched in order to select three appropriate points from a single list. If it is still not possible to find three such points in any list, the functions returns unsuccessfully.

PEXGeoNormFillAreaSet assumes the handedness is PEXVertexOrderRightHand.

Specify the handedness argument to generate normals that match the orientation of the coordinate system that the vertex data uses. PEXVertexOrderRightHand indicates that the coordinate system is right-handed, and PEXVertexOrderLeftHand indicates that the normals are to be "flipped" from the right-handed orientation to match a left-handed coordinate system.

If the facet attributes does not contain the bit PEXGANormal, then this utility does not compute the geometric normal. However, this utility still returns successfully.

Errors