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