Ubuntu Manpage: SoShapeHints — node that provides hints about shapes

Provided by: inventor-doc_2.1.5-10-18_all

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
     }