source files: [xc]shp.[ch]
(XG.3D-INSERT-FRUSTUM :THING <thing> [ :TRANSFORM <xtfm> ] [ :X <num> ] [ :Y <num> ] [ :Z <num> ] [ :SCALE <num> ] [ :SCALE-X <num> ] [ :SCALE-Y <num> ] [ :SCALE-Z <num> ] )
The <thing> must be a 'thing' in the :DRAW <camera> sense, a disembodied propertylist containing a :POINT-RELATION, and also a :FACET-RELATION. Both must be rank-1.
This call inserts eight X-Y-Z points in :POINT-RELATION, defining the corners of a frustum, and also five four-sided facets in :FACET-RELATION. (Currently, the back face is not inserted.)
Before SCALING, the resulting frustum is centered on :X :Y :Z, facing you as you look toward positive Z, of width 1.0 in x and y, and depth 0.1.
If :TRANSFORM is supplied, it must be an instance of CLASS-MATRIX44, and will be used to transform the frustum exactly as if by XG.3D-TRANSFORM-THING.