defines a ShapeHints node of VRML specifying properties of geometry and its appearance.
The ShapeHints node indicates that IndexedFaceSets are solid, contain ordered vertices, or
contain convex faces.
These hints allow VRML implementations to optimize certain rendering features.
Optimizations that may be performed include enabling back-face culling and disabling
two-sided lighting. For example, if an object is solid and has ordered vertices, an
implementation may turn on backface culling and turn off two-sided lighting. To ensure
that an IndexedFaceSet can be viewed from either direction, set shapeType to be
UNKNOWN_SHAPE_TYPE.
If you know that your shapes are closed and will alwsys be viewed from the outside, set
vertexOrdering to be either CLOCKWISE or COUNTERCLOCKWISE (depending on
how you built your object), and set shapeType to be SOLID. Placing this near the top of
your VRML file will allow the scene to be rendered much faster.
The ShapeHints node also affects how default normals are generated. When an
IndexedFaceSet has to generate default normals, it uses the creaseAngle field to determine
which edges should be smoothly shaded and which ones should have a sharp crease. The
crease angle is the angle between surface normals on adjacent polygons. For example, a
crease angle of .5 radians (the default value) means that an edge between two adjacent
polygonal faces will be smooth shaded if the normals to the two faces form an angle that is
less than .5 radians (about 30 degrees). Otherwise, it will be faceted.
#include <Vrml_ShapeHints.hxx>
Constructor & Destructor Documentation
Member Function Documentation
void Vrml_ShapeHints::SetFaceType |
( |
const Vrml_FaceType |
aFaceType | ) |
|
The documentation for this class was generated from the following file: