pfHit(3pf) OpenGL Performer 3.2.2 libpr C Reference Pages pfHit(3pf)NAME
pfQueryHit, pfMQueryHit, pfGetHitClassType - Intersection and bounding
operations on drawable geometry
FUNCTION SPECIFICATION
#include <Performer/pr.h>
int pfQueryHit(pfHit *hit, uint which, void *dst);
int pfMQueryHit(pfHit *hit, uint *which, void *dst);
pfType * pfGetHitClassType(void);
DESCRIPTIONpfQueryHit and pfMQueryHit read out information from the pfHit object.
pfQueryHit copies an item from the object into the location specified by
dst. which specifies the item to be copied using one of the PFHIT_
tokens listed above. pfMQueryHit copies a series of items sequentially
into the buffer specified by dst. The items and their order are defined
by a NULL-terminated array of query tokens pointed to by which. For both
functions, the return value is the number of bytes written to the
destination buffer.
PFQHIT_FLAGS returns a bit vector indicating the validity of information
in the structure. It is formed by a bitwise OR-ing of the PFHIT_POINT,
PFHIT_NORM, PFHIT_PRIM, PFHIT_TRI, PFHIT_VERTS and PFHIT_XFORM symbols.
Flags Bit Validity
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PFHIT_POINT Point of intersection
PFHIT_NORM Polygon normal
PFHIT_PRIM Index of primitive in pfGeoSet
PFHIT_TRI Index of triangle within primitive
PFHIT_VERTS Triangle vertices
PFHIT_XFORM Non-identity transformation matrix
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Other queried quantities are valid if non-NULL.
PFQHIT_POINT, PFQHIT_NORM and PFQHIT_SEG query the point of intersection,
the normal of the triangle at that point, and the current segment as
clipped by the intersection process. All are in local coordinates, i.e.
they do not include the transformations of pfSCSes and pfDCSes above them
in the scene graph. When intersecting with primitives inside a pfGeoSet,
PFQHIT_PRIM, PFQHIT_TRI and PFQHIT_VERTS provide the index of the
primitive within the pfGeoSet, the triangle within the primitive, and the
vertices of the intersected triangle, respectively. PFQHIT_GSET returns
the GeoSet. PFQHIT_NODE returns the parent pfGeode.
PFQHIT_PATH returns a pfPath* denoting the traversal path. Like the
pfHit object it is reused and should not be freed.
pfGetHitClassType returns the pfType* for the class pfHit. The pfType*
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pfHit(3pf) OpenGL Performer 3.2.2 libpr C Reference Pages pfHit(3pf)
returned by pfGetHitClassType is the same as the pfType* returned by
invoking pfGetType on any instance of class pfHit. Because OpenGL
Performer allows subclassing of built-in types, when decisions are made
based on the type of an object, it is usually better to use pfIsOfType to
test if an object is of a type derived from a Performer type rather than
to test for strict equality of the pfType*'s.
SEE ALSO
pfCylAroundSegs, pfNodeIsectSegs, pfGeoSet, pfObject, pfSeg
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