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SoShapeHints Class Reference

The SoShapeHints class is a node containing hints about how to render geometry. More...

#include <Inventor/nodes/SoShapeHints.h>

Inheritance diagram for SoShapeHints:
SoNode SoFieldContainer SoBase

Public Types

enum  ShapeType { UNKNOWN_SHAPE_TYPE = SoShapeHintsElement::UNKNOWN_SHAPE_TYPE, SOLID = SoShapeHintsElement::SOLID }
enum  FaceType { UNKNOWN_FACE_TYPE = SoShapeHintsElement::UNKNOWN_FACE_TYPE, CONVEX = SoShapeHintsElement::CONVEX }
enum  WindingType { NO_WINDING_TYPE = 0 }
- Public Types inherited from SoNode
enum  NodeType {
  INVENTOR = 0x0000, VRML1 = 0x0001, VRML2 = 0x0002, INVENTOR_1 = 0x0004,
  INVENTOR_2_0 = 0x0008, INVENTOR_2_1 = 0x0010, INVENTOR_2_5 = 0x0020, INVENTOR_2_6 = 0x0040,
  COIN_1_0 = 0x0080, COIN_2_0 = 0x0100, EXTENSION = 0x0200, COIN_2_2 = 0x0400,
  COIN_2_3 = 0x0800, COIN_2_4 = 0x1000, INVENTOR_5_0 = 0x2000, COIN_2_5 = 0x4000,
  COIN_3_0 = 0x8000, INVENTOR_6_0 = 0x10000, COIN_4_0 = 0x20000

Public Member Functions

virtual SoType getTypeId (void) const
 Returns the type identification of an object derived from a class inheriting SoBase. This is used for runtime type checking and "downward" casting. More...
 SoShapeHints (void)
virtual void doAction (SoAction *action)
virtual void GLRender (SoGLRenderAction *action)
virtual void callback (SoCallbackAction *action)
virtual void getBoundingBox (SoGetBoundingBoxAction *action)
virtual void pick (SoPickAction *action)
- Public Member Functions inherited from SoNode
void setOverride (const SbBool state)
SbBool isOverride (void) const
void setNodeType (const NodeType type)
NodeType getNodeType (void) const
virtual SoNodecopy (SbBool copyconnections=FALSE) const
virtual SbBool affectsState (void) const
virtual void GLRenderBelowPath (SoGLRenderAction *action)
virtual void GLRenderInPath (SoGLRenderAction *action)
virtual void GLRenderOffPath (SoGLRenderAction *action)
virtual void getMatrix (SoGetMatrixAction *action)
virtual void handleEvent (SoHandleEventAction *action)
virtual void rayPick (SoRayPickAction *action)
virtual void search (SoSearchAction *action)
virtual void write (SoWriteAction *action)
virtual void audioRender (SoAudioRenderAction *action)
virtual void getPrimitiveCount (SoGetPrimitiveCountAction *action)
virtual void grabEventsSetup (void)
virtual void grabEventsCleanup (void)
virtual void startNotify (void)
virtual void notify (SoNotList *l)
SbUniqueId getNodeId (void) const
virtual SoChildListgetChildren (void) const
virtual void writeInstance (SoOutput *out)
virtual SoNodeaddToCopyDict (void) const
virtual void copyContents (const SoFieldContainer *from, SbBool copyconnections)
virtual SoFieldContainercopyThroughConnection (void) const
- Public Member Functions inherited from SoFieldContainer
void setToDefaults (void)
SbBool hasDefaultValues (void) const
SbBool fieldsAreEqual (const SoFieldContainer *container) const
void copyFieldValues (const SoFieldContainer *container, SbBool copyconnections=FALSE)
SbBool set (const char *const fielddata)
void get (SbString &fielddata)
virtual int getFields (SoFieldList &l) const
virtual int getAllFields (SoFieldList &l) const
virtual SoFieldgetField (const SbName &name) const
virtual SoFieldgetEventIn (const SbName &name) const
virtual SoFieldgetEventOut (const SbName &name) const
SbBool getFieldName (const SoField *const field, SbName &name) const
SbBool enableNotify (const SbBool flag)
SbBool isNotifyEnabled (void) const
SbBool set (const char *fielddata, SoInput *input)
void get (SbString &fielddata, SoOutput *out)
virtual SbBool validateNewFieldValue (SoField *field, void *newval)
virtual void addWriteReference (SoOutput *out, SbBool isfromfield=FALSE)
SbBool getIsBuiltIn (void) const
virtual void getFieldsMemorySize (size_t &managed, size_t &unmanaged) const
void setUserData (void *userdata) const
void * getUserData (void) const
- Public Member Functions inherited from SoBase
void ref (void) const
void unref (void) const
void unrefNoDelete (void) const
int32_t getRefCount (void) const
void touch (void)
SbBool isOfType (SoType type) const
 Returns TRUE if the type of this object is either of the same type or inherited from type. More...
virtual SbName getName (void) const
virtual void setName (const SbName &newname)
void addAuditor (void *const auditor, const SoNotRec::Type type)
void removeAuditor (void *const auditor, const SoNotRec::Type type)
const SoAuditorListgetAuditors (void) const
SbBool shouldWrite (void)
void assertAlive (void) const

Static Public Member Functions

static SoType getClassTypeId (void)
static void initClass (void)
- Static Public Member Functions inherited from SoNode
static uint32_t getCompatibilityTypes (const SoType &nodetype)
static SoType getClassTypeId (void)
static SoNodegetByName (const SbName &name)
static int getByName (const SbName &name, SoNodeList &l)
static void initClass (void)
static void initClasses (void)
static SbUniqueId getNextNodeId (void)
static int getActionMethodIndex (const SoType type)
static void getBoundingBoxS (SoAction *action, SoNode *node)
static void GLRenderS (SoAction *action, SoNode *node)
static void callbackS (SoAction *action, SoNode *node)
static void getMatrixS (SoAction *action, SoNode *node)
static void handleEventS (SoAction *action, SoNode *node)
static void pickS (SoAction *action, SoNode *node)
static void rayPickS (SoAction *action, SoNode *node)
static void searchS (SoAction *action, SoNode *node)
static void writeS (SoAction *action, SoNode *node)
static void audioRenderS (SoAction *action, SoNode *node)
static void getPrimitiveCountS (SoAction *action, SoNode *node)
- Static Public Member Functions inherited from SoFieldContainer
static void initClass (void)
static SoType getClassTypeId (void)
static void cleanupClass (void)
static void initCopyDict (void)
static void addCopy (const SoFieldContainer *orig, const SoFieldContainer *copy)
static SoFieldContainercheckCopy (const SoFieldContainer *orig)
static SoFieldContainerfindCopy (const SoFieldContainer *orig, const SbBool copyconnections)
static void copyDone (void)
- Static Public Member Functions inherited from SoBase
static void initClass (void)
 Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system.
static SoType getClassTypeId (void)
 This static method returns the SoType object associated with objects of this class.
static void addName (SoBase *const base, const char *const name)
static void removeName (SoBase *const base, const char *const name)
static void incrementCurrentWriteCounter (void)
static void decrementCurrentWriteCounter (void)
static SoBasegetNamedBase (const SbName &name, SoType type)
static int getNamedBases (const SbName &name, SoBaseList &baselist, SoType type)
static SbBool read (SoInput *input, SoBase *&base, SoType expectedtype)
static void setInstancePrefix (const SbString &c)
static void setTraceRefs (SbBool trace)
static SbBool getTraceRefs (void)
static SbBool connectRoute (SoInput *input, const SbName &fromnodename, const SbName &fromfieldname, const SbName &tonodename, const SbName &tofieldname)
static SbBool readRoute (SoInput *input)

Public Attributes

SoSFEnum vertexOrdering
SoSFEnum shapeType
SoSFEnum faceType
SoSFEnum windingType
SoSFBool useVBO
SoSFFloat creaseAngle

Protected Member Functions

virtual const SoFieldDatagetFieldData (void) const
virtual ~SoShapeHints ()
- Protected Member Functions inherited from SoNode
 SoNode (void)
virtual ~SoNode ()
virtual SbBool readInstance (SoInput *in, unsigned short flags)
- Protected Member Functions inherited from SoFieldContainer
 SoFieldContainer (void)
virtual ~SoFieldContainer ()
- Protected Member Functions inherited from SoBase
 SoBase (void)
virtual ~SoBase ()
virtual void destroy (void)
SbBool hasMultipleWriteRefs (void) const
SbBool writeHeader (SoOutput *out, SbBool isgroup, SbBool isengine) const
void writeFooter (SoOutput *out) const
virtual const char * getFileFormatName (void) const
virtual SoNotRec createNotRec (void)

Static Protected Member Functions

static const SoFieldData ** getFieldDataPtr (void)
- Static Protected Member Functions inherited from SoNode
static const SoFieldData ** getFieldDataPtr (void)
static void setNextActionMethodIndex (int index)
static int getNextActionMethodIndex (void)
static void incNextActionMethodIndex (void)
static void setCompatibilityTypes (const SoType &nodetype, const uint32_t bitmask)
- Static Protected Member Functions inherited from SoBase
static uint32_t getCurrentWriteCounter (void)
static void staticDataLock (void)
static void staticDataUnlock (void)

Additional Inherited Members

- Protected Types inherited from SoBase
enum  BaseFlags { IS_ENGINE = 0x01, IS_GROUP = 0x02 }
- Protected Attributes inherited from SoNode
SbUniqueId uniqueId
- Protected Attributes inherited from SoFieldContainer
SbBool isBuiltIn
- Static Protected Attributes inherited from SoNode
static SbUniqueId nextUniqueId = 1
static int nextActionMethodIndex = 0

Detailed Description

The SoShapeHints class is a node containing hints about how to render geometry.

The SoShapeHints node is used to set up clues to the rendering subsystem about how particular aspects of the subsequent geometry in the scene graph should be drawn.

Here is an example on how to display a scene in wireframe mode which only shows the triangles facing towards the camera.

#include <Inventor/nodes/SoCone.h>
#include <Inventor/nodes/SoDrawStyle.h>
#include <Inventor/nodes/SoLightModel.h>
#include <Inventor/nodes/SoSeparator.h>
#include <Inventor/nodes/SoShapeHints.h>
#include <Inventor/Win/SoWin.h>
#include <Inventor/Win/viewers/SoWinExaminerViewer.h>
int main(int, char * argv[])
HWND window = SoWin::init(argv[0]);
SoSeparator * root = new SoSeparator;
// wireframe
SoDrawStyle * drawStyle = new SoDrawStyle;
drawStyle->style = SoDrawStyle::LINES;
// back-face culling
SoShapeHints * shapeHints = new SoShapeHints;
// keep a solid color
SoLightModel * lightModel = new SoLightModel;
// a cone
SoCone * cone = new SoCone;
// set up a window
SoWinExaminerViewer * viewer = new SoWinExaminerViewer(window);
SbViewportRegion vpRegion = viewer->getViewportRegion();
delete viewer;
return 0;

The default settings of the rendering system are tuned towards programmer convenience. For instance, the default is to render both sides of all polygons to make sure we avoid any "holes" in the geometry if the vertex ordering should happen to differ for different polygons.

If the programmer gives up some of this convenience and uses SoShapeHints nodes to more closely specify information about the scene graph geometry, the clues given by the SoShapeHints node(s) will then be used by the rendering subsystem to avoid certain costly operations. Significant gains in rendering speed could be seen as a result.

Be aware that the way backface culling and two-sided lighting is decided by the rendering system is not at all intuitive. Here are the common rules of how primitive shapes will render themselves with regard to how the SoShapeHints::vertexOrdering and SoShapeHints::shapeType fields are set:

  • vertexOrdering == CLOCKWISE or COUNTERCLOCKWISE, shapeType == SOLID: causes primitives to be backface culled and rendered with one-sided lighting.

  • vertexOrdering == CLOCKWISE or COUNTERCLOCKWISE, shapeType == UNKNOWN_SHAPE_TYPE: primitives are not backface culled, and they are rendered with two-sided lighting.

  • vertexOrdering == UNKNOWN_ORDERING, any shapeType: primitives are not backface culled, and they are rendered with one-sided lighting. The OpenGL vertex ordering will be set to counterclockwise ordering.

The UNKNOWN_ORDERING enum has a special and non-intuitive meaning. The ordering is really set to counterclockwise – in OpenGL and when generating normals. However, if you want to render your geometry with one-sided lighting and backface culling disabled, you have to use this enum value, and your polygons need to be in counterclockwise ordering.


Member Enumeration Documentation

◆ VertexOrdering

Enumeration of available ways to specify ordering of vertices for a polygon.


Ordering not known, render both sides of the polygon.


Vertices are specified in a clockwise order.


Vertices are specified in a counterclockwise order.

◆ ShapeType

Enumeration of different shape types.


Nothing known about the shape, be conservative when rendering.


The subsequent shapes in the graph are all known to be completely "closed", solid 3D shapes. Backface culling will be done if vertexOrdering is known.

◆ FaceType

Enumeration of polygon face types.


Signifies: nothing is known about subsequent polygon data, be conservative when rendering.

All polygons in the scene will be analyzed to see if they need to be tessellated (broken up) into triangles before passed on to the underlying immediate mode rendering system.

The OpenGL rendering system handles most complex polygon types, but not all: it can for instance have problems with many-sided, concave polygons (concave polygons are "hollow", that is: rounded inwards). Coin's internal tessellator will most often handle the cases that OpenGL fails on.

So if you are seeing weird artifacts in how complex polygons are rendered, try to change the SoShapeHints::faceType field to this value and see if they are then rendered correctly.

Beware that turning on this functionality might have the effect of making the rendering performance worse. If it has a noticeable effect on your particular scene graph, we advise that you investigate whether you could change how the polygons are generated for Coin rendering and then avoid using this flag.


Subsequent faces are all convex, so turn off the check for and tessellation of not convex faces.

Subsequent polygons from faceset-type nodes (like SoFaceSet and SoIndexedFaceSet) will be sent unmodified to OpenGL, thereby assuming that the polygons are in a form handled by OpenGL.

Constructor & Destructor Documentation

◆ SoShapeHints()

SoShapeHints::SoShapeHints ( void  )


◆ ~SoShapeHints()

SoShapeHints::~SoShapeHints ( )


Member Function Documentation

◆ getTypeId()

SoType SoShapeHints::getTypeId ( void  ) const

Returns the type identification of an object derived from a class inheriting SoBase. This is used for runtime type checking and "downward" casting.

Usage example:

void foo(SoNode * node)
if (node->getTypeId() == SoFile::getClassTypeId()) {
SoFile * filenode = (SoFile *)node; // safe downward cast, knows the type

For application programmers wanting to extend the library with new nodes, engines, nodekits, draggers or others: this method needs to be overridden in all subclasses. This is typically done as part of setting up the full type system for extension classes, which is usually accomplished by using the predefined macros available through for instance Inventor/nodes/SoSubNode.h (SO_NODE_INIT_CLASS and SO_NODE_CONSTRUCTOR for node classes), Inventor/engines/SoSubEngine.h (for engine classes) and so on.

For more information on writing Coin extensions, see the class documentation of the top level superclasses for the various class groups.

Implements SoBase.

◆ getFieldData()

const SoFieldData * SoShapeHints::getFieldData ( void  ) const

Returns a pointer to the class-wide field data storage object for this instance. If no fields are present, returns NULL.

Reimplemented from SoFieldContainer.

◆ doAction()

void SoShapeHints::doAction ( SoAction action)

This function performs the typical operation of a node for any action.

Reimplemented from SoNode.

◆ GLRender()

void SoShapeHints::GLRender ( SoGLRenderAction action)

Action method for the SoGLRenderAction.

This is called during rendering traversals. Nodes influencing the rendering state in any way or want to throw geometry primitives at OpenGL override this method.

Reimplemented from SoNode.

◆ callback()

void SoShapeHints::callback ( SoCallbackAction action)

Action method for SoCallbackAction.

Simply updates the state according to how the node behaves for the render action, so the application programmer can use the SoCallbackAction for extracting information about the scene graph.

Reimplemented from SoNode.

◆ getBoundingBox()

void SoShapeHints::getBoundingBox ( SoGetBoundingBoxAction action)

Action method for the SoGetBoundingBoxAction.

Calculates bounding box and center coordinates for node and modifies the values of the action to encompass the bounding box for this node and to shift the center point for the scene more towards the one for this node.

Nodes influencing how geometry nodes calculate their bounding box also override this method to change the relevant state variables.

Reimplemented from SoNode.

◆ pick()

void SoShapeHints::pick ( SoPickAction action)

Action method for SoPickAction.

Does common processing for SoPickAction action instances.

Reimplemented from SoNode.

Member Data Documentation

◆ vertexOrdering

SoSFEnum SoShapeHints::vertexOrdering

Specifies how vertices are ordered for polygon faces.

Set this field to SoShapeHints::CLOCKWISE or SoShapeHints::COUNTERCLOCKWISE if possible to turn on backface culling and thereby optimize rendering.

Default value is SoShapeHints::UNKNOWN_ORDERING.

◆ shapeType

SoSFEnum SoShapeHints::shapeType

Hint about whether or not shapes are known to be "closed". Default value is SoShapeHints::UNKNOWN_SHAPE_TYPE.

◆ faceType

SoSFEnum SoShapeHints::faceType

Hint about whether or not polygon faces are known to be convex. Default value is SoShapeHints::CONVEX.

◆ creaseAngle

SoSFFloat SoShapeHints::creaseAngle

When normals are automatically generated by Coin (i.e. SoNormal nodes are not used), this is the smallest angle between two faces where we would still calculate normals to do flat shading.

If the angle between the normals of two neighboring faces is less than the value of this field, the faces will be smooth shaded around their common edge.

The angle is specified in radians, and the default value is 0.0, meaning no smoothing will be done by default.

The documentation for this class was generated from the following files: