252 Chapter 4 Scene Graphs
The type itself is stored in the data member
Type. It is in public scope because there
are no side effects in reading or writing it. However, the block is marked for internal
use by the engine. There is no need for an application writer to manipulate the type.
The value
GT_POLYPOINT indicates that the object is a collection of points. The
value
GT_TRIMESH indicates that the object is a triangle mesh. The three values with
POLYLINE as part of their names are used for collections of line segments. GT_
POLYLINE_SEGMENTS
is for a set of line segments with no connections between them.
GT_POLYLINE_OPEN is for a polyline, a set of line segments where each segment end-
point is shared by at most two lines. The initial and final segments ...