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. More...

#include <Inventor/nodes/SoShapeHints.h>

Inheritance diagram for SoShapeHints:

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

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 run-time 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 SoNode *	copy (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)

uint32_t	getNodeId (void) const

virtual SoChildList *	getChildren (void) const

virtual void	writeInstance (SoOutput *out)

virtual SoNode *	addToCopyDict (void) const

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

virtual SoFieldContainer *	copyThroughConnection (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 SoField *	getField (const SbName &name) const

virtual SoField *	getEventIn (const SbName &name) const

virtual SoField *	getEventOut (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 SoAuditorList &	getAuditors (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 SoNode *	getByName (const SbName &name)

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

static void	initClass (void)

static void	initClasses (void)

static uint32_t	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 SoFieldContainer *	checkCopy (const SoFieldContainer *orig)

static SoFieldContainer *	findCopy (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 SoBase *	getNamedBase (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 SoFieldData *	getFieldData (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
uint32_t	uniqueId

Protected Attributes inherited from SoFieldContainer
SbBool	isBuiltIn

Static Protected Attributes inherited from SoNode
static uint32_t	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;
  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 is 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 counter clockwise ordering.

The UNKNOWN_ORDERING enum has a special and non-intuitive meaning. The ordering is really set to counter clockwise – 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 counter clockwise ordering.

FILE FORMAT/DEFAULTS:

ShapeHints {
    vertexOrdering UNKNOWN_ORDERING
    shapeType UNKNOWN_SHAPE_TYPE
    faceType CONVEX
    creaseAngle 0
}

Member Enumeration Documentation

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 counter-clockwise order.

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.

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 needs 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 noticable effect on your particular scenegraph, 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 inconvex 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 ( void )

Constructor.

SoShapeHints::~SoShapeHints ( )

protectedvirtual

Destructor.

Member Function Documentation

SoType SoShapeHints::getTypeId ( void ) const

virtual

Returns the type identification of an object derived from a class inheriting SoBase. This is used for run-time 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 pre-defined 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 toplevel superclasses for the various class groups.

Implements SoBase.

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.

void SoShapeHints::doAction ( SoAction * action )

virtual

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

Reimplemented from SoNode.

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 who wants to throw geometry primitives at OpenGL overrides this method.

Reimplemented from SoNode.

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.

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 calculates their bounding box also overrides this method to change the relevant state variables.

Reimplemented from SoNode.

void SoShapeHints::pick ( SoPickAction * action )

virtual

Action method for SoPickAction.

Does common processing for SoPickAction action instances.

Reimplemented from SoNode.

Member Data Documentation

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.

SoSFEnum SoShapeHints::shapeType

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

SoSFEnum SoShapeHints::faceType

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

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 flatshading.

If the angle between the normals of two neighboring faces is less than the value of this field, the faces will be smoothshaded 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:

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

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation