cxGeo cxGeoPolysDefine( int npoint, float *point, int nindex, int *index )
integer function cxGeoPolysDefine(n,point, nindex,INDEX) integer npoint real point(3, npoint) integer nindex integer index(nindex)
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.