SoPolygonOffset Class Reference

Property node that sets the polygon offset. More...

#include <Inventor/nodes/SoPolygonOffset.h>

Inheritance diagram for SoPolygonOffset:

Public Types
enum	Style {   FILLED = SoPolygonOffsetElement::FILLED ,   LINES = SoPolygonOffsetElement::LINES ,   POINTS = SoPolygonOffsetElement::POINTS }
	Offset style. More...

Public Member Functions
virtual SoType	getTypeId () const
	Returns the type identifier for this specific instance.
	SoPolygonOffset ()
	Constructor.
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 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
SoSFFloat	factor
	Specifies a scale factor that is used to create a variable depth offset for each polygon.
SoSFFloat	units
	Is multiplied by an OpenGL implementation-specific value to create a constant depth offset.
SoSFBitMask	styles
	A bit-wise combination of FILLED, LINES, and POINTS that determines which polygon modes should be offset.
SoSFBool	on
	Enables/disables polygon offset.

Detailed Description

Property node that sets the polygon offset.

This class encapsulates the OpenGL 1.1 glPolygonOffset() function. This node can be used to offset polygons that are at the exact same depth to avoid depth buffer artifacts, commonly called z-buffer stitching.

NOTE: SoPolygonOffset, as its name implies, only works with polygonal geometry.

SoPolygonOffset affects filled primitives such as SoFaceSet and SoTriangleStripSet.
It also affects lines and points in the limited sense that it affects polygonal primitives when the draw style is set to LINES or POINTS. However, because polygon offset does not affect non-polygonal geometry, primitives such as SoLineSet and SoPointSet cannot be offset with SoPolygonOffset(). To avoid depth buffer artifacts with mixed polygonal and non-polygonal geometry, you should "push" the polygonal geometry away from the camera.

Note: There is only one offset value (combination of factor and units) in the traversal state at any given time.

The value of the offset is factor * z + r * units, where

• z is a measurement of the change in depth relative to the screen area of the polygon (commonly called the depth slope), and
• r is the smallest value that is guaranteed to produce a resolvable offset for a given OpenGL implementation.

So units produces a constant depth offset and factor produces a variable depth offset which is zero when a polygon is perpendicular to the view vector (parallel to the view plane) and increases as the depth slope increases.

Both factor and units may be either positive or negative. A positive offset value pushes primitives away from the camera and a negative value pulls them closer. Generally a small value, like 1.0, is sufficient for both parameters.

FILE FORMAT/DEFAULT

PolygonOffset {

factor	1
units	100
styles	FILLED
on	TRUE

}

ACTION BEHAVIOR

SoGLRenderAction
Calls glPolygonOffset and enables or disables the polygon offset feature as specified. Sets: SoPolyonOffsetElement.

SEE ALSO

SoDepthOffset, SoDepthBuffer, SoOverlayGroup

Definition at line 100 of file SoPolygonOffset.h.

Member Enumeration Documentation

Style

enum SoPolygonOffset::Style

Offset style.

Enumerator
FILLED	Filled.
LINES	Lines.
POINTS	Points.

Definition at line 107 of file SoPolygonOffset.h.

Constructor & Destructor Documentation

SoPolygonOffset()

SoPolygonOffset::SoPolygonOffset

(

)

Constructor.

Member Function Documentation

getClassTypeId()

static SoType SoPolygonOffset::getClassTypeId ( )

static

Returns the type identifier for this class.

getTypeId()

virtual SoType SoPolygonOffset::getTypeId ( ) const

virtual

Returns the type identifier for this specific instance.

Reimplemented from SoNode.

isOverride()

virtual SbBool SoPolygonOffset::isOverride ( ) const

inlinevirtual

Returns the state of the override field.

Reimplemented from SoNode.

Definition at line 157 of file SoPolygonOffset.h.

setOverride()

virtual void SoPolygonOffset::setOverride ( const SbBool  state )

inlinevirtual

Set the state of the override field.

see SoNode::setOverride doc.

Reimplemented from SoNode.

Definition at line 151 of file SoPolygonOffset.h.

Member Data Documentation

factor

SoSFFloat SoPolygonOffset::factor

Specifies a scale factor that is used to create a variable depth offset for each polygon.

Positive values push polygons away from the camera (opposite of SoDepthOffset). Default = 1.0.

Definition at line 122 of file SoPolygonOffset.h.

on

SoSFBool SoPolygonOffset::on

Enables/disables polygon offset.

Default = TRUE.

Definition at line 140 of file SoPolygonOffset.h.

styles

SoSFBitMask SoPolygonOffset::styles

A bit-wise combination of FILLED, LINES, and POINTS that determines which polygon modes should be offset.

Default = FILLED.

Definition at line 135 of file SoPolygonOffset.h.

units

SoSFFloat SoPolygonOffset::units

Is multiplied by an OpenGL implementation-specific value to create a constant depth offset.

Positive values push polygons away from the camera (oppsite of SoDepthOffset). Default = 100.0.

Definition at line 129 of file SoPolygonOffset.h.

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

• Inventor/nodes/SoPolygonOffset.h