Open Inventor Release 2024.1.1
 
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SoDepthOffset Class Reference

VSG extension Property node that applies a depth offset. More...

#include <Inventor/nodes/SoDepthOffset.h>

+ Inheritance diagram for SoDepthOffset:

Public Member Functions

virtual SoType getTypeId () const
 Returns the type identifier for this specific instance.
 
 SoDepthOffset ()
 Constructor.
 
- Public Member Functions inherited from SoNode
virtual void setOverride (const SbBool state)
 Turns the override flag on or off.
 
virtual SbBool isOverride () const
 Returns the state of the override flag.
 
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 offset
 Offset to apply to the projection matrix.
 
SoSFBool on
 Enables depth offset.
 

Detailed Description

VSG extension Property node that applies a depth offset.

This node can be used to offset shapes that are co-planar, in order to resolve depth buffer artifacts, commonly called z-buffer "stitching".

The effect is similar to SoPolygonOffset but this node uses a different algorithm (based on Lengyel's method from Game Programming Gems and improved by VSG) in which the projection matrix is modified to offset subsequent geometry. As a result it has advantages over SoPolygonOffset in some cases. Specifically, SoDepthOffset applies its offset value to all types of geometry, not just polygons, and does not require any additional per-vertex calculations on the GPU.

The offset value is accumulated in the traversal state. For example:

Note that if the accumulation of offset values during the traversal is greater than 1, the accumulated offset value is normalized so that, in this case, the offset values are not absolute but relative to each other.

SoDepthOffset has two limitations. First, since it modifies the projection matrix during traversal, it may prevent building a render cache for part of the scene graph. Second, the offset does not take into account the depth slope of the geometry (as SoPolygonOffset does), so a larger offset may be required for geometry that is not perpendicular to the view vector (facing the camera).

The presence of a SoDepthOffset node in the scene graph causes depth buffer values to be different, even if 'offset' is equal to 0.

The render caching issue is easily handled, by adjusting your scene graph structure, just as you would for any non-cacheable node, to ensure that the actual shape nodes are cached even if the parent group node cannot cache:
For example, using this scene graph structure:

instead of this one:

FILE FORMAT/DEFAULT

    DepthOffset {
    offset 0.001
    on TRUE
    }

ACTION BEHAVIOR

SEE ALSO

SoPolygonOffset, SoDepthBuffer, SoOverlayGroup

Definition at line 91 of file SoDepthOffset.h.

Constructor & Destructor Documentation

◆ SoDepthOffset()

SoDepthOffset::SoDepthOffset ( )

Constructor.

Member Function Documentation

◆ getClassTypeId()

static SoType SoDepthOffset::getClassTypeId ( )
static

Returns the type identifier for this class.


◆ getTypeId()

virtual SoType SoDepthOffset::getTypeId ( ) const
virtual

Returns the type identifier for this specific instance.

Reimplemented from SoNode.

Member Data Documentation

◆ offset

SoSFFloat SoDepthOffset::offset

Offset to apply to the projection matrix.


Positive values move geometry toward the camera (the opposite of SoPolygonOffset). Offset value must be in the range [-0.5 .. 0.5] (normalized depth coordinates). Default is 0.001

Definition at line 107 of file SoDepthOffset.h.

◆ on

SoSFBool SoDepthOffset::on

Enables depth offset.

NOTE: field available since Open Inventor 8.1

Definition at line 113 of file SoDepthOffset.h.


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