Node that provides hints about shapes. More...
#include <Inventor/nodes/SoShapeHints.h>
Public Types | |
enum | VertexOrdering { UNKNOWN_ORDERING = SoShapeHintsElement::UNKNOWN_ORDERING , CLOCKWISE = SoShapeHintsElement::CLOCKWISE , COUNTERCLOCKWISE = SoShapeHintsElement::COUNTERCLOCKWISE } |
Hints about ordering of face vertices: if ordering of all vertices of all faces is known to be consistent when viewed from "outside" shape or not. More... | |
enum | ShapeType { UNKNOWN_SHAPE_TYPE = SoShapeHintsElement::UNKNOWN_SHAPE_TYPE , SOLID = SoShapeHintsElement::SOLID } |
Hints about entire shape: if shape is known to be a solid object, as opposed to a surface. More... | |
enum | FaceType { UNKNOWN_FACE_TYPE = SoShapeHintsElement::UNKNOWN_FACE_TYPE , CONVEX = SoShapeHintsElement::CONVEX } |
Hints about faces of shape: if all faces are known to be convex or not. More... | |
enum | WindingType { NO_WINDING_TYPE = SoShapeHintsElement::NO_WINDING_TYPE , ODD_TYPE = SoShapeHintsElement::ODD_TYPE , NON_ZERO_TYPE = SoShapeHintsElement::NON_ZERO_TYPE , POSITIVE_TYPE = SoShapeHintsElement::POSITIVE_TYPE , NEGATIVE_TYPE = SoShapeHintsElement::NEGATIVE_TYPE , ABS_GEQ_TWO_TYPE = SoShapeHintsElement::ABS_GEQ_TWO_TYPE } |
Winding type possible values. More... | |
Public Member Functions | |
virtual SoType | getTypeId () const |
Returns the type identifier for this specific instance. | |
SoShapeHints () | |
Creates a shape hints node with default settings. | |
virtual void | setOverride (const SbBool state) |
Set the state of the override field. | |
virtual SbBool | isOverride () const |
Returns the state of the override field. | |
Public Member Functions inherited from SoNode | |
virtual SoNode * | copy (SbBool copyConnections=FALSE) const |
Creates and returns an exact copy of the node. | |
virtual SbBool | affectsState () const |
Returns TRUE if a node has an effect on the state during traversal. | |
virtual void | touch () |
Marks an instance as modified, simulating a change to it. | |
Public Member Functions inherited from SoFieldContainer | |
void | setToDefaults () |
Sets all fields in this object to their default values. | |
SbBool | hasDefaultValues () const |
Returns TRUE if all of the object's fields have their default values. | |
SbBool | fieldsAreEqual (const SoFieldContainer *fc) const |
Returns TRUE if this object's fields are exactly equal to fc's fields. | |
void | copyFieldValues (const SoFieldContainer *fc, SbBool copyConnections=FALSE) |
Copies the contents of fc's fields into this object's fields. | |
SoNONUNICODE SbBool | set (const char *fieldDataString) |
Sets one or more fields in this object to the values specified in the given string, which should be a string in the Open Inventor file format. | |
SbBool | set (const SbString &fieldDataString) |
Sets one or more fields in this object to the values specified in the given string, which should be a string in the Open Inventor file format. | |
void | get (SbString &fieldDataString) |
Returns the values of the fields of this object in the Open Inventor ASCII file format in the given string. | |
virtual int | getFields (SoFieldList &list) const |
Appends references to all of this object's fields to resultList, and returns the number of fields appended. | |
virtual int | getAllFields (SoFieldList &list) const |
Returns a list of fields, including the eventIn's and eventOut's. | |
virtual SoField * | getField (const SbName &fieldName) const |
Returns a the field of this object whose name is fieldName. | |
virtual SoField * | getEventIn (const SbName &fieldName) const |
Returns a the eventIn with the given name. | |
virtual SoField * | getEventOut (const SbName &fieldName) const |
Returns the eventOut with the given name. | |
SbBool | getFieldName (const SoField *field, SbName &fieldName) const |
Returns the name of the given field in the fieldName argument. | |
SbBool | enableNotify (SbBool flag) |
Notification at this Field Container is enabled (if flag == TRUE) or disabled (if flag == FALSE). | |
SbBool | isNotifyEnabled () const |
Notification is the process of telling interested objects that this object has changed. | |
virtual void | setUserData (void *data) |
Sets application data. | |
void * | getUserData (void) const |
Gets user application data. | |
Public Member Functions inherited from SoBase | |
virtual SbName | getName () const |
Returns the name of an instance. | |
virtual void | setName (const SbName &name) |
Sets the name of an instance. | |
void | setSynchronizable (const bool b) |
Sets this to be a ScaleViz synchronizable object. | |
bool | isSynchronizable () const |
Gets the ScaleViz synchronizable state of this object. | |
Public Member Functions inherited from SoRefCounter | |
void | ref () const |
Adds a reference to an instance. | |
void | unref () const |
Removes a reference from an instance. | |
void | unrefNoDelete () const |
unrefNoDelete() should be called when it is desired to decrement the reference count, but not delete the instance if this brings the reference count to zero. | |
int | getRefCount () const |
Returns current reference count. | |
void | lock () const |
lock this instance. | |
void | unlock () const |
unlock this instance. | |
Public Member Functions inherited from SoTypedObject | |
SbBool | isOfType (const SoType &type) const |
Returns TRUE if this object is of the type specified in type or is derived from that type. | |
template<typename TypedObjectClass > | |
SbBool | isOfType () const |
Returns TRUE if this object is of the type of class TypedObjectClass or is derived from that class. | |
Static Public Member Functions | |
static SoType | getClassTypeId () |
Returns the type identifier for this class. | |
static SbBool | isVBOSupported () |
Indicates if Vertex Buffer Object (VBO) is supported by your graphics board. | |
Static Public Member Functions inherited from SoNode | |
static SoType | getClassTypeId () |
Returns the type identifier for this class. | |
static SoNode * | getByName (const SbName &name) |
A node's name can be set using SoBase::setName(). | |
static int | getByName (const SbName &name, SoNodeList &list) |
A node's name can be set using SoBase::setName(). | |
Static Public Member Functions inherited from SoFieldContainer | |
static SoType | getClassTypeId () |
Returns the type of this class. | |
Static Public Member Functions inherited from SoBase | |
static SoType | getClassTypeId () |
Returns type identifier for this class. | |
Static Public Member Functions inherited from SoTypedObject | |
static SoType | getClassTypeId () |
Returns the type identifier for this class. | |
Public Attributes | |
SoSFEnum | vertexOrdering |
Indicates how the vertices of faces are ordered. | |
SoSFEnum | shapeType |
Indicates whether the shape is known to enclose a volume (SOLID) or not. | |
SoSFEnum | faceType |
Indicates whether each face is convex. | |
SoSFEnum | windingType |
Indicates the winding rule used to define holes in a polygon. | |
SoSFBool | useVBO |
This field controls whether subsequent shapes in the scene graph can use OpenGL Vertex Buffer Objects (VBO) to speed up rendering. | |
SoSFFloat | creaseAngle |
Indicates the minimum angle (in radians) between two adjacent face normals required to form a sharp crease at the edge when normal vectors are computed automatically by Open Inventor. | |
SoSFFloat | neighborTolerance |
Specifies the tolerance value to use when default normals are computed. | |
Node that provides hints about shapes.
By default, Open 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 Open 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, Open 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.
Summary:
Note: Two-sided lighting is automatically enabled for VolumeViz "slice" primitives, such as SoOrthoSlice and SoVolumeSkin.
This node allows the creation of polygons with holes. See the windingType field description, SoIndexedFaceSet, and SoFaceSet for details.
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.
creaseAngle = 0 | creaseAngle = 0.5 | creaseAngle = PI |
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Smooth shaded means that the normal vectors of all the faces that share a vertex are averaged together to compute the normal vector for that vertex.
Normal averaging |
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Normal generation is fastest when the creaseAngle is 0 (the default), producing one normal per facet. However, if a vertex is shared by two (or more) faces that should be faceted, the result of normal generation will be multiple normal vectors (one for each face) associated with that vertex. This is in conflict with using OpenGL Vertex Buffer Objects (VBO), which usually provide the best performance. VBO rendering only allows per-vertex (not per-face) normal vectors and only one normal vector per vertex. Some high-level shapes, like SoIndexedFaceSet, will automatically reorganize the geometry data to produce the requested appearance and still use VBOs for rendering. Lower level shapes like SoBufferedShape will ignore the creaseAngle field and compute normals using a crease angle of Pi in order to use VBOs for rendering. A creaseAngle of Pi produces one averaged normal per vertex.
See SoVertexShape for more information about Vertex Buffer Objects and shape rendering.
vertexOrdering | UNKNOWN_ORDERING |
shapeType | UNKNOWN_SHAPE_TYPE |
faceType | CONVEX |
windingType | NO_WINDING_TYPE |
creaseAngle | 0 |
neighborTolerance | 1e-6 |
useVBO | TRUE |
SoVertexShape SoIndexedFaceSet SoFaceSet
Definition at line 171 of file SoShapeHints.h.
Hints about faces of shape: if all faces are known to be convex or not.
Enumerator | |
---|---|
UNKNOWN_FACE_TYPE | Nothing is known about faces. |
CONVEX | All faces are convex. |
Definition at line 212 of file SoShapeHints.h.
Hints about entire shape: if shape is known to be a solid object, as opposed to a surface.
Enumerator | |
---|---|
UNKNOWN_SHAPE_TYPE | Nothing is known about the shape. |
SOLID | The shape encloses a volume. |
Definition at line 200 of file SoShapeHints.h.
Hints about ordering of face vertices: if ordering of all vertices of all faces is known to be consistent when viewed from "outside" shape or not.
Definition at line 181 of file SoShapeHints.h.
Winding type possible values.
Definition at line 224 of file SoShapeHints.h.
SoShapeHints::SoShapeHints | ( | ) |
Creates a shape hints node with default settings.
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static |
Returns the type identifier for this class.
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virtual |
Returns the type identifier for this specific instance.
Reimplemented from SoNode.
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inlinevirtual |
Returns the state of the override field.
Reimplemented from SoNode.
Definition at line 388 of file SoShapeHints.h.
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static |
Indicates if Vertex Buffer Object (VBO) is supported by your graphics board.
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inlinevirtual |
Set the state of the override field.
see SoNode::setOverride doc.
Reimplemented from SoNode.
Definition at line 382 of file SoShapeHints.h.
SoSFFloat SoShapeHints::creaseAngle |
Indicates the minimum angle (in radians) between two adjacent face normals required to form a sharp crease at the edge when normal vectors are computed automatically by Open Inventor.
It has no effect when normal vectors are explicitly provided by the application.
Definition at line 349 of file SoShapeHints.h.
SoSFEnum SoShapeHints::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. Use enum FaceType. Default is CONVEX.
Definition at line 280 of file SoShapeHints.h.
SoSFFloat SoShapeHints::neighborTolerance |
Specifies the tolerance value to use when default normals are computed.
The default is 1e-6.
Specifically it determines which (other) points in the shape are close enough to influence the normal at each vertex.
Setting a smaller tolerance value will select a smaller number of points and can reduce the time required for computing normals on very large, very dense geometry.
If the OIV_NORMGEN_TOLERANCE environment variable is set, the default is 1/OIV_NORMGEN_TOLERANCE.
NOTE: field available since Open Inventor 8.0
Definition at line 366 of file SoShapeHints.h.
SoSFEnum SoShapeHints::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. Use enum ShapeType. Default is UNKNOWN_SHAPE_TYPE.
Definition at line 272 of file SoShapeHints.h.
SoSFBool SoShapeHints::useVBO |
This field controls whether subsequent shapes in the scene graph can use OpenGL Vertex Buffer Objects (VBO) to speed up rendering.
Default is TRUE (since Open Inventor 8.1). The default value can be set using the OIV_FORCE_USE_VBO environment variable (see SoPreferences).
In most cases there is no reason to set this field. Open Inventor will automatically choose the best rendering strategy. For example, VBOs generally provide the best performance for large shapes (many vertices), but not necessarily for small shapes. In specific cases it may be useful to influence these decisions using this field and/or the related environment variables including OIV_MIN_VERTEX_VBO and OIV_MIN_VERTEX_VAVBO_NOCACHE. See SoVertexShape for more discussion about shape rendering strategy.
NOTE: field available since Open Inventor 5.0
Definition at line 341 of file SoShapeHints.h.
SoSFEnum SoShapeHints::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). Use enum VertexOrdering. Default is UNKNOWN_ORDERING.
Definition at line 265 of file SoShapeHints.h.
SoSFEnum SoShapeHints::windingType |
Indicates the winding rule used to define holes in a polygon.
It is used by SoIndexedFaceSet and SoFaceSet to determine which parts of the polygon are on the interior and which are on the exterior and should not be filled. By default this field value is NO_WINDING_TYPE, that is, no winding rules are used, so there are no holes. Use enum WindingType.
For a single contour, the winding number of a point is the signed number of revolutions we make around that point while traveling once around the contour (where a counterclockwise revolution is positive and a clockwise revolution is negative). When there are several contours, the individual winding numbers are summed. This procedure associates a signed integer value with each point in the plane. Note that the winding number is the same for all points in a single region.
The following figure shows three sets of contours and winding numbers for points inside those contours. In the left set, all three contours are counterclockwise, so each nested interior region adds one to the winding number. For the middle set, the two interior contours are drawn clockwise, so the winding number decreases and actually becomes negative.
br |
br |
NOTE: In LINES drawing style (see SoDrawStyle), if windingType is not NO_WINDING_TYPE, or if faceType is UNKNOWN_FACE_TYPE, the edges of the tessellated triangles will be drawn.
NOTE: field available since Open Inventor 4.0
Definition at line 323 of file SoShapeHints.h.