SoShapeHints(3IV)

NAME
     SoShapeHints - node that provides hints about shapes

INHERITS FROM
     SoBase > SoFieldContainer > SoNode > SoShapeHints

SYNOPSIS
     #include <Inventor/nodes/SoShapeHints.h>

     enum VertexOrdering {
          SoShapeHints::UNKNOWN_ORDERING
                                   Ordering of vertices is unknown
          SoShapeHints::CLOCKWISE  Face vertices are ordered clockwise (from
                                        the outside)
          SoShapeHints::COUNTERCLOCKWISE
                                   Face vertices are ordered counterclockwise
                                        (from the outside)
     }

     enum ShapeType {
          SoShapeHints::UNKNOWN_SHAPE_TYPE
                               Nothing is known about the shape
          SoShapeHints::SOLID  The shape encloses a volume
     }

     enum FaceType {
          SoShapeHints::UNKNOWN_FACE_TYPE
                                Nothing is known about faces
          SoShapeHints::CONVEX  All faces are convex
     }

          Fields from class SoShapeHints:

     SoSFEnum            vertexOrdering
     SoSFEnum            shapeType
     SoSFEnum            faceType
     SoSFFloat           creaseAngle

          Methods from class SoShapeHints:

                         SoShapeHints()
     static SoType       getClassTypeId()

          Methods from class SoNode:

     void                setOverride(SbBool state)
     SbBool              isOverride() const
     SoNode *            copy(SbBool copyConnections = FALSE) const
     virtual SbBool      affectsState() const
     static SoNode *     getByName(const SbName &name)
     static int          getByName(const SbName &name, SoNodeList &list)

          Methods from class SoFieldContainer:

     void                setToDefaults()
     SbBool              hasDefaultValues() const
     SbBool              fieldsAreEqual(const SoFieldContainer *fc) const
     void                copyFieldValues(const SoFieldContainer *fc, SbBool
                              copyConnections = FALSE)
     SbBool              set(const char *fieldDataString)
     void                get(SbString &fieldDataString)
     virtual int         getFields(SoFieldList &resultList) const
     virtual SoField *   getField(const SbName &fieldName) const
     SbBool              getFieldName(const SoField *field, SbName &fieldName)
                              const
     SbBool              isNotifyEnabled() const
     SbBool              enableNotify(SbBool flag)

          Methods from class SoBase:

     void                ref()
     void                unref() const
     void                unrefNoDelete() const
     void                touch()
     virtual SoType      getTypeId() const
     SbBool              isOfType(SoType type) const
     virtual void        setName(const SbName &name)
     virtual SbName      getName() const


DESCRIPTION
     By default, Inventor assumes very little about the shapes it renders. You
     can use the SoShapeHints node to indicate that vertex-based shapes (those
     derived from SoVertexShape) are solid, contain ordered vertices, or
     contain convex faces. For fastest rendering, specify SOLID,
     COUNTERCLOCKWISE, CONVEX shapes.

     These hints allow Inventor 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, Inventor turns on backface culling and turns off
     two-sided lighting. If the object is not solid but has ordered vertices,
     it turns off backface culling and turns on two-sided lighting. In all
     other cases, both backface culling and two-sided lighting are off.

     The SoShapeHints node also affects how default normals are generated.
     When a node derived from SoVertexShape has to generate default normals,
     it uses the creaseAngle field to determine which edges should be smooth-
     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 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. Normal generation is fastest when the creaseAngle is 0 (the
     default), producing one normal per facet.  A creaseAngle of pi produces
     one averaged normal per vertex.

FIELDS
     SoSFEnum            vertexOrdering
          Indicates how the vertices of faces are ordered. CLOCKWISE ordering
          means that the vertices of each face form a clockwise loop around
          the face, when viewed from the outside (the side toward which the
          normal points).

     SoSFEnum            shapeType
          Indicates whether the shape is known to enclose a volume (SOLID) or
          not. If the inside (the side away from the surface normal) of any
          part of the shape is visible, the shape is not solid.

     SoSFEnum            faceType
          Indicates whether each face is convex. Because the penalty for non-
          convex faces is very steep (faces must be triangulated expensively),
          the default assumes all faces are convex. Therefore, shapes with
          concave faces may not be displayed correctly unless this hint is set
          to UNKNOWN_FACE_TYPE.

     SoSFFloat           creaseAngle
          Indicates the minimum angle (in radians) between two adjacent face
          normals required to form a sharp crease at the edge when default
          normals are computed and used.


METHODS
                         SoShapeHints()
          Creates a shape hints node with default settings.

     static SoType       getClassTypeId()
          Returns type identifier for this class.


ACTION BEHAVIOR
     SoGLRenderAction, SoCallbackAction, SoRayPickAction,
     SoGetBoundingBoxAction
          Sets the state to contain the hints; sets up optimizations based on
          the hints.


FILE FORMAT/DEFAULTS
     ShapeHints {
          vertexOrdering  UNKNOWN_ORDERING
          shapeType       UNKNOWN_SHAPE_TYPE
          faceType        CONVEX
          creaseAngle     0
     }

SEE ALSO
     SoVertexShape