Open Inventor Release 2023.2.3
 
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SoPolygonOffset Class Reference

VSG extension 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 SoNodecopy (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 SoFieldgetField (const SbName &fieldName) const
 Returns a the field of this object whose name is fieldName.
 
virtual SoFieldgetEventIn (const SbName &fieldName) const
 Returns a the eventIn with the given name.
 
virtual SoFieldgetEventOut (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 SoNodegetByName (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

VSG extension 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

Definition at line 100 of file SoPolygonOffset.h.

Member Enumeration Documentation

◆ 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.


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