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

#include <Inventor/nodes/SoShapeHints.h>

Inheritance diagram for SoShapeHints:

Public Types
enum	FaceType { UNKNOWN_FACE_TYPE = SoShapeHintsElement::UNKNOWN_FACE_TYPE , CONVEX = SoShapeHintsElement::CONVEX }

enum	ShapeType { UNKNOWN_SHAPE_TYPE = SoShapeHintsElement::UNKNOWN_SHAPE_TYPE , SOLID = SoShapeHintsElement::SOLID }

enum	VertexOrdering { UNKNOWN_ORDERING = SoShapeHintsElement::UNKNOWN_ORDERING , CLOCKWISE = SoShapeHintsElement::CLOCKWISE , COUNTERCLOCKWISE = SoShapeHintsElement::COUNTERCLOCKWISE }

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
	SoShapeHints (void)

virtual void	callback (SoCallbackAction *action)

virtual void	doAction (SoAction *action)

virtual void	getBoundingBox (SoGetBoundingBoxAction *action)

virtual SoType	getTypeId (void) const

virtual void	GLRender (SoGLRenderAction *action)

virtual void	pick (SoPickAction *action)

Public Member Functions inherited from SoNode
virtual SoNode *	addToCopyDict (void) const

virtual SbBool	affectsState (void) const

virtual void	audioRender (SoAudioRenderAction *action)

virtual SoNode *	copy (SbBool copyconnections=FALSE) const

virtual void	copyContents (const SoFieldContainer *from, SbBool copyconnections)

virtual SoFieldContainer *	copyThroughConnection (void) const

virtual SoChildList *	getChildren (void) const

virtual void	getMatrix (SoGetMatrixAction *action)

SbUniqueId	getNodeId (void) const

NodeType	getNodeType (void) const

virtual void	getPrimitiveCount (SoGetPrimitiveCountAction *action)

virtual void	GLRenderBelowPath (SoGLRenderAction *action)

virtual void	GLRenderInPath (SoGLRenderAction *action)

virtual void	GLRenderOffPath (SoGLRenderAction *action)

virtual void	grabEventsCleanup (void)

virtual void	grabEventsSetup (void)

virtual void	handleEvent (SoHandleEventAction *action)

SbBool	isOverride (void) const

virtual void	notify (SoNotList *l)

virtual void	rayPick (SoRayPickAction *action)

virtual void	search (SoSearchAction *action)

void	setNodeType (const NodeType type)

void	setOverride (const SbBool state)

virtual void	startNotify (void)

virtual void	write (SoWriteAction *action)

virtual void	writeInstance (SoOutput *out)

Public Member Functions inherited from SoFieldContainer
virtual void	addWriteReference (SoOutput *out, SbBool isfromfield=FALSE)

void	copyFieldValues (const SoFieldContainer *container, SbBool copyconnections=FALSE)

SbBool	enableNotify (const SbBool flag)

SbBool	fieldsAreEqual (const SoFieldContainer *container) const

void	get (SbString &fielddata)

void	get (SbString &fielddata, SoOutput *out)

virtual int	getAllFields (SoFieldList &l) const

virtual SoField *	getEventIn (const SbName &name) const

virtual SoField *	getEventOut (const SbName &name) const

virtual SoField *	getField (const SbName &name) const

SbBool	getFieldName (const SoField *const field, SbName &name) const

virtual int	getFields (SoFieldList &l) const

virtual void	getFieldsMemorySize (size_t &managed, size_t &unmanaged) const

SbBool	getIsBuiltIn (void) const

void *	getUserData (void) const

SbBool	hasDefaultValues (void) const

SbBool	isNotifyEnabled (void) const

SbBool	set (const char *const fielddata)

SbBool	set (const char fielddata, SoInput input)

void	setToDefaults (void)

void	setUserData (void *userdata) const

virtual SbBool	validateNewFieldValue (SoField field, void newval)

Public Member Functions inherited from SoBase
void	addAuditor (void *const auditor, const SoNotRec::Type type)

void	assertAlive (void) const

const SoAuditorList &	getAuditors (void) const

virtual SbName	getName (void) const

int32_t	getRefCount (void) const

SbBool	isOfType (SoType type) const
	Returns `TRUE` if the type of this object is either of the same type or inherited from type.

void	ref (void) const

void	removeAuditor (void *const auditor, const SoNotRec::Type type)

virtual void	setName (const SbName &newname)

SbBool	shouldWrite (void)

void	touch (void)

void	unref (void) const

void	unrefNoDelete (void) const

Static Public Member Functions
static SoType	getClassTypeId (void)

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 Public Member Functions inherited from SoNode
static void	audioRenderS (SoAction action, SoNode node)

static void	callbackS (SoAction action, SoNode node)

static int	getActionMethodIndex (const SoType type)

static void	getBoundingBoxS (SoAction action, SoNode node)

static SoNode *	getByName (const SbName &name)

static int	getByName (const SbName &name, SoNodeList &l)

static SoType	getClassTypeId (void)

static uint32_t	getCompatibilityTypes (const SoType &nodetype)

static void	getMatrixS (SoAction action, SoNode node)

static SbUniqueId	getNextNodeId (void)

static void	getPrimitiveCountS (SoAction action, SoNode node)

static void	GLRenderS (SoAction action, SoNode node)

static void	handleEventS (SoAction action, SoNode node)

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 void	initClasses (void)

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 Public Member Functions inherited from SoFieldContainer
static void	addCopy (const SoFieldContainer orig, const SoFieldContainer copy)

static SoFieldContainer *	checkCopy (const SoFieldContainer *orig)

static void	cleanupClass (void)

static void	copyDone (void)

static SoFieldContainer *	findCopy (const SoFieldContainer *orig, const SbBool copyconnections)

static SoType	getClassTypeId (void)
	This static method returns the SoType object associated with objects of this class.

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 void	initCopyDict (void)

Static Public Member Functions inherited from SoBase
static void	addName (SoBase const base, const char const name)

static SbBool	connectRoute (SoInput *input, const SbName &fromnodename, const SbName &fromfieldname, const SbName &tonodename, const SbName &tofieldname)

static void	decrementCurrentWriteCounter (void)

static SoType	getClassTypeId (void)
	This static method returns the SoType object associated with objects of this class.

static SoBase *	getNamedBase (const SbName &name, SoType type)

static int	getNamedBases (const SbName &name, SoBaseList &baselist, SoType type)

static SbBool	getTraceRefs (void)

static void	incrementCurrentWriteCounter (void)

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 SbBool	read (SoInput input, SoBase &base, SoType expectedtype)

static SbBool	readRoute (SoInput *input)

static void	removeName (SoBase const base, const char const name)

static void	setInstancePrefix (const SbString &c)

static void	setTraceRefs (SbBool trace)

Public Attributes
SoSFFloat	creaseAngle

SoSFEnum	faceType

SoSFEnum	shapeType

SoSFBool	useVBO

SoSFEnum	vertexOrdering

SoSFEnum	windingType

Protected Member Functions
virtual	~SoShapeHints ()

virtual const SoFieldData *	getFieldData (void) const

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 SoNotRec	createNotRec (void)

virtual void	destroy (void)

virtual const char *	getFileFormatName (void) const

SbBool	hasMultipleWriteRefs (void) const

void	writeFooter (SoOutput *out) const

SbBool	writeHeader (SoOutput *out, SbBool isgroup, SbBool isengine) const

Static Protected Member Functions
static const SoFieldData **	getFieldDataPtr (void)

Static Protected Member Functions inherited from SoNode
static const SoFieldData **	getFieldDataPtr (void)

static int	getNextActionMethodIndex (void)

static void	incNextActionMethodIndex (void)

static void	setCompatibilityTypes (const SoType &nodetype, const uint32_t bitmask)

static void	setNextActionMethodIndex (int index)

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 int	nextActionMethodIndex = 0

static SbUniqueId	nextUniqueId = 1

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;
  root->addChild(drawStyle);
 
  // back-face culling
  SoShapeHints * shapeHints = new SoShapeHints;
  shapeHints->vertexOrdering = SoShapeHints::COUNTERCLOCKWISE;
  shapeHints->shapeType = SoShapeHints::SOLID;
  root->addChild(shapeHints);
 
  // keep a solid color
  SoLightModel * lightModel = new SoLightModel;
  lightModel->model = SoLightModel::BASE_COLOR;
  root->addChild(lightModel);
 
  // a cone
  SoCone * cone = new SoCone;
  root->addChild(cone);
 
  // set up a window
  SoWinExaminerViewer * viewer = new SoWinExaminerViewer(window);
  SbViewportRegion vpRegion = viewer->getViewportRegion();
  viewer->setSceneGraph(root);
  viewer->show();
 
  SoWin::mainLoop();
  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.

FILE FORMAT/DEFAULTS:

ShapeHints {
    vertexOrdering UNKNOWN_ORDERING
    shapeType UNKNOWN_SHAPE_TYPE
    faceType CONVEX
    creaseAngle 0
}

Member Enumeration Documentation

◆ FaceType

enum SoShapeHints::FaceType

Enumeration of polygon face types.

Enumerator

UNKNOWN_FACE_TYPE

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.

CONVEX

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.

◆ ShapeType

enum SoShapeHints::ShapeType

Enumeration of different shape types.

Enumerator
UNKNOWN_SHAPE_TYPE	Nothing known about the shape, be conservative when rendering.
SOLID	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.

◆ VertexOrdering

enum SoShapeHints::VertexOrdering

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

Enumerator
UNKNOWN_ORDERING	Ordering not known, render both sides of the polygon.
CLOCKWISE	Vertices are specified in a clockwise order.
COUNTERCLOCKWISE	Vertices are specified in a counterclockwise order.

◆ WindingType

enum SoShapeHints::WindingType

Enumeration of different winding types.

Enumerator
NO_WINDING_TYPE	Draw without holes.

Constructor & Destructor Documentation

◆ SoShapeHints()

SoShapeHints::SoShapeHints ( void )

Constructor.

◆ ~SoShapeHints()

SoShapeHints::~SoShapeHints ( )

protectedvirtual

Destructor.

Member Function Documentation

◆ callback()

void SoShapeHints::callback ( SoCallbackAction * action )

virtual

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.

◆ doAction()

void SoShapeHints::doAction ( SoAction * action )

virtual

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

Reimplemented from SoNode.

◆ getBoundingBox()

void SoShapeHints::getBoundingBox ( SoGetBoundingBoxAction * action )

virtual

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.

◆ getClassTypeId()

SoType SoShapeHints::getClassTypeId ( void )

static

This static method returns the SoType object associated with objects of this class.

◆ getFieldData()

const SoFieldData * SoShapeHints::getFieldData ( void ) const

protectedvirtual

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

Reimplemented from SoFieldContainer.

◆ getFieldDataPtr()

const SoFieldData ** SoShapeHints::getFieldDataPtr ( void )

staticprotected

This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

Returns the SoFieldData class which holds information about fields in this node.

◆ getTypeId()

SoType SoShapeHints::getTypeId ( void ) const

virtual

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

Implements SoBase.

◆ GLRender()

void SoShapeHints::GLRender ( SoGLRenderAction * action )

virtual

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.

◆ pick()

void SoShapeHints::pick ( SoPickAction * action )

virtual

Action method for SoPickAction.

Does common processing for SoPickAction action instances.

Reimplemented from SoNode.

Member Data Documentation

◆ 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.

◆ faceType

SoSFEnum SoShapeHints::faceType

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

◆ shapeType

SoSFEnum SoShapeHints::shapeType

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

◆ 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.

◆ windingType

SoSFEnum SoShapeHints::windingType

Hint about the winding type that is used to define holes in a polygon. Default value is SoShapeHints::NO_WINDING_TYPE, i.e. no winding type is used and therefore no holes are drawn. Up to now Coin does not support other winding types than the default.

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

SoShapeHints.h
SoShapeHints.cpp

Public Types

Public Member Functions

Static Public Member Functions

Public Attributes

Protected Member Functions

Static Protected Member Functions

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ FaceType

◆ ShapeType

◆ VertexOrdering

◆ WindingType

Constructor & Destructor Documentation

◆ SoShapeHints()

◆ ~SoShapeHints()

Member Function Documentation

◆ callback()

◆ doAction()

◆ getBoundingBox()

◆ getClassTypeId()

◆ getFieldData()

◆ getFieldDataPtr()

◆ getTypeId()

◆ GLRender()

◆ pick()

Member Data Documentation

◆ creaseAngle

◆ faceType

◆ shapeType

◆ vertexOrdering

◆ windingType