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