NAME

C SPECIFICATION

#include <cx/Geometry.h>

cxGeo cxGeoPolysDefine(
 int npoint,
 float *point,
 int nindex,
 long *index )

FORTRAN SPECIFICATION

integer function cxGeoPolysDefine(n,point, nindex,INDEX)
integer npoint
real point(3, npoint)
integer nindex
integer index(nindex)

PARAMETERS

npoint

Number of points.

point

An array of XYZ triples for vertices.

nindex

Number of indices.

index

Indices into the points array.

DESCRIPTION

Indexing of vertices is zero-based, i.e. the first vertex is referenced by index 0, and the last by npoint - 1. An index element value of -1 indicates the end of a polygon.

The return value is a tag for this object that may be used to reference it at a later time with cxGeoFocus(3E).

Valid attributes are colors, normals, and transparencies. Attribute distribution may be CX_GEO_PER_OBJECT, CX_GEO_PER_FACE, CX_GEO_PER_VERTEX, or CX_GEO_PER_VERTEX_INDEXED.

Polygons specified by cxGeoPolysDefine must have their vertices supplied in a counter-clockwise fashion so that the implicit frontfacing/backfacing normal for the polygon is computed correctly according to the "right-hand rule". Specifying a normal for the polygon using cxGeoNormalAdd will not override this frontfacing/backfacing normal computation for purposes of rendering. If you do not adhere to this ordering, you may get unexpected results when the polygon is rendered in 3-D rendering modules which display the geometry.

SEE ALSO