SoShadowGroup Class Reference

Shadow casting group node More...

#include <Inventor/nodes/SoShadowGroup.h>

Inheritance diagram for SoShadowGroup:

Public Types
enum	VisibilityFlag {   ABSOLUTE_RADIUS ,   LONGEST_BBOX_EDGE_FACTOR }
	visibilityRadius interpretation More...
enum	ShadowingMethod { VARIANCE_SHADOW_MAP }
	Shadowing techniques. More...

Public Member Functions
virtual SoType	getTypeId () const
	Returns the type identifier for this specific instance.
	SoShadowGroup ()
	Default constructor.
	SoShadowGroup (int nChildren)
	Constructor that takes approximate number of children.
Public Member Functions inherited from SoGroup
	SoGroup ()
	Creates an empty group node.
	SoGroup (int nChildren)
	Constructor that takes approximate number of children.
virtual void	addChild (SoNode *child)
	Adds a child as last one in group.
virtual void	insertChild (SoNode *child, int newChildIndex)
	Adds a child so that it becomes the one with the given index.
virtual SoNode *	getChild (int index) const
	Returns pointer the child node with the given index.
virtual int	findChild (const SoNode *child) const
	Finds index of given child within group.
virtual int	getNumChildren () const
	Returns number of children.
virtual void	removeChild (int index)
	Removes child with given index from group.
virtual void	removeChild (SoNode *child)
	Removes first instance of given child from group.
virtual void	removeAllChildren ()
	Removes all children from group.
virtual void	replaceChild (int index, SoNode *newChild)
	Replaces child with given index with new child.
virtual void	replaceChild (SoNode *oldChild, SoNode *newChild)
	Replaces first instance of given child with new child.
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 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 SbBool	isSupported (SoShadowGroup::ShadowingMethod method=SoShadowGroup::VARIANCE_SHADOW_MAP)
	Indicates if shadow casting is supported by your graphic board.
Static Public Member Functions inherited from SoGroup
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
SoSFBool	isActive
	Activates/deactivates the shadowing.
SoSFFloat	intensity
	Specifies the intensity of the shadow.
SoSFFloat	precision
	Specifies the precision of the shadow.
SoSFFloat	quality
	Specifies the quality of the shadow.
SoSFBool	shadowCachingEnabled
	Indicates if a cache should be used for computing the shadows.
SoSFFloat	visibilityRadius
	Shadows are only computed within "visibility radius" distance from the camera position.
SoSFEnum	visibilityFlag
	Specifies how visibilityRadius is interpreted.
SoSFInt32	smoothFactor
	Set the smoothness of shadows.
SoSFFloat	minVariance
	Increasing this value will decrease possible self-shadowing artifacts but will make shadows fade away.
SoSFFloat	lightBleedingReduction
	In some cases, a halo may appear around shadows intersecting each other.
SoSFEnum	method
	Specifies the shadowing technique to use.
Public Attributes inherited from SoGroup
SoSFBool	boundingBoxIgnoring
	Whether to ignore this node during bounding box traversal.

Detailed Description

Shadow casting group node

This group node performs real-time shadow casting. Because shadows depends on a lot of OpenInventor elements, it is recommended to put children of this group under a SoSeparator in order to have a cache. Each shape within this group will be included in the shadow casting computation. A shape may cast a shadow on other shapes or on itself (self-shadowing), and/or may be shadowed by other shapes within the group. The current shadow style is used to determine if shapes cast a shadow and/or can be shadowed (see SoShadowStyle).

This class defines a single shadowing method. The method field allows for future shadowing methods to be added.

• VARIANCE_SHADOW_MAP : This mode allows to display soft shadows. The smoothFactor field can be used to increase or decrease the softness. Aliasing won't be displayed, but on large scenes shadows will progressively fade away. Increasing quality will reduce this problem. Only the last on state directional light is used during rendering, other lights are ignored.

  Shaders
  Only the VARIANCE_SHADOW_MAP method is available with shaders (custom or internal). In order to use shadows with user defined GLSL shaders (SoShaderProgram or SoVolumeShader), the following functions must be used in the shader programs.
  In the vertex shader:

  • void OivSetupShadowVertex(): Must be called in the vertex shader.

  In the fragment shader:

  • float OivComputeShadow(): Returns a scalar in [0-1]. 0 means fragment is fully shadowed, 1 means no shadow. Should be used to modify the fragment color.
  • void OivGenerateShadowMap(): Must be called during the shadowmap pass in order to create the shadowmap. During this pass, the shader must not write to gl_FragColor. Use the uniform OivShadowPass to know when the shadowmap is being computed.

  The following uniform is available in vertex and fragment shaders:

  • uniform bool OivShadowPass: Is true if the shadowmap is currently being rendered

  The following code can be used as a skeleton for a GLSL shader that works with shadows:

  // The vertex shader:
  void OivSetupShadowVertex();
  void main()
  {
    ..userCode..
    //Needed for shadowing
    OivSetupShadowVertex();
  }
   
  // The fragment shader:
  //If true we are in shadowmap generation pass
  uniform bool OivShadowPass;
   
  void OivGenerateShadowMap();
  float OivComputeShadow();
  void main()
  {
    if ( !OivShadowPass ) {
      ..compute fragment color here..
      // Define the final color
      gl_FragColor.xyz = fragColor.xyz * OivComputeShadow();
      gl_FragColor.w = fragColor.w;
    }
    else {
      // Output the shadowmap during the shadow map pass
      OivGenerateShadowMap();
    }
  } 

  Transparency:
  Transparent objects are treated as follows, depending on the transparency type:

  • NO_SORT: Transparent objects cast a shadow and are shadowed but the shadow intensity doesn't depend on the transparency value (the same shadow is displayed for full transparent shapes and opaque shapes).
  • OPAQUE_FIRST, SORTED_OBJECT and SORTED_PIXEL: Same as previous case for VARIANCE_SHADOW_MAP.

  Texture units:
  In VARIANCE_SHADOW_MAP mode, this node reserves texture unit OIV_SHADOW_TEXTURE_UNIT0 for its rendering (see SoPreferences to set these). If this value is not set the application can specify which texture units OpenInventor should automatically use by setting environment variables (see SoPreferences). The texture units between OIV_FIRST_RESERVED_TEXTURE_UNIT and OIV_FIRST_RESERVED_TEXTURE_UNIT + SoShaderProgram::getNumReservedTextures() -1 inclusive are reserved for internal OpenInventor use. If OIV_FIRST_RESERVED_TEXTURE_UNIT is not set, its default value is SoFragmentShader::getMaxTextureImageUnit()-SoShaderProgram::getNumReservedTextures(). Note: The value returned by SoShaderProgram::getNumReservedTextures() may change between OpenInventor versions. The total number of available texture units depends on the graphics hardware.

  Hardware requirements:
  The Shadow and Depth Texture OpenGL extensions (standard in OpenGL 1.4) are used if they are available and generally improve performance.
  In order to increase quality and performance of the shadows, OpenGL PBuffers are used. PBuffers are a limited resource on some systems. Set OIV_PBUFFER_ENABLE to 0 to disallow use of PBuffers.

  A DirectX 10 graphics board is needed to support VARIANCE_SHADOW_MAP.

  Use the isSupported() static method to determine if the current graphics board supports shadowing.

  Limitations

  • SoShadowGroup cannot be nested by design.

  Notes:

  • Geometry cannot receive shadows if lighting is disabled.
    For example if an SoLightModel node sets the lighting model to BASE_COLOR.
  • Geometry cannot receive shadows if a texture is applied using the DECAL or REPLACE models.

FILE FORMAT/DEFAULT

ShadowGroup {

isActive	TRUE
isShapesBefore	FALSE
intensity	0.5
precision	0.5
quality	0.5
shadowCachingEnabled	TRUE
visibilityRadius	1.0
visibilityFlag	LONGEST_BBOX_EDGE_FACTOR
smoothFactor	1
minVariance	1e-5
method	VARIANCE_SHADOW_MAP
lightBleedingReduction	0.01

}

SEE ALSO

SoShadowStyle

Definition at line 180 of file SoShadowGroup.h.

Member Enumeration Documentation

ShadowingMethod

enum SoShadowGroup::ShadowingMethod

Shadowing techniques.

Enumerator
VARIANCE_SHADOW_MAP	Shadows with soft edges.

Definition at line 209 of file SoShadowGroup.h.

VisibilityFlag

enum SoShadowGroup::VisibilityFlag

visibilityRadius interpretation

Enumerator
ABSOLUTE_RADIUS	visibilityRadius is interpreted as an absolute value.
LONGEST_BBOX_EDGE_FACTOR	The longest edge of the scene bounding box will be multiplied by the value of visibilityRadius. The resulting value will be the radius within which shadows are computed.

Definition at line 189 of file SoShadowGroup.h.

Constructor & Destructor Documentation

SoShadowGroup() [1/2]

SoShadowGroup::SoShadowGroup

(

)

Default constructor.

SoShadowGroup() [2/2]

SoShadowGroup::SoShadowGroup

(

int

nChildren

)

Constructor that takes approximate number of children.

Member Function Documentation

getClassTypeId()

static SoType SoShadowGroup::getClassTypeId ( )

static

Returns the type identifier for this class.

getTypeId()

virtual SoType SoShadowGroup::getTypeId ( ) const

virtual

Returns the type identifier for this specific instance.

Reimplemented from SoGroup.

isSupported()

static SbBool SoShadowGroup::isSupported ( SoShadowGroup::ShadowingMethod  method = SoShadowGroup::VARIANCE_SHADOW_MAP )

static

Indicates if shadow casting is supported by your graphic board.

When using a debug build of Open Inventor, some "no context available" warning messages may be generated. You can ignore them or see SoGLExtension for an example of using SoGLContext to avoid them.

Member Data Documentation

intensity

SoSFFloat SoShadowGroup::intensity

Specifies the intensity of the shadow.

0 = lowest intensity (the shadow is invisible), 1 = highest intensity (the shadow is solid black).

Definition at line 240 of file SoShadowGroup.h.

isActive

SoSFBool SoShadowGroup::isActive

Activates/deactivates the shadowing.

If deactivated, this SoShadowGroup behaves like an SoGroup.

Definition at line 233 of file SoShadowGroup.h.

lightBleedingReduction

SoSFFloat SoShadowGroup::lightBleedingReduction

In some cases, a halo may appear around shadows intersecting each other.

Increasing this value will decrease this effect. Default value is safe for most scenes. Default is 0.01 and range is [0-1].

NOTE: field available since Open Inventor 8.1

Definition at line 322 of file SoShadowGroup.h.

method

SoSFEnum SoShadowGroup::method

Specifies the shadowing technique to use.

Use enum ShadowingMethod. Default is VARIANCE_SHADOW_MAP.

NOTE: field available since Open Inventor 8.1

Definition at line 330 of file SoShadowGroup.h.

minVariance

SoSFFloat SoShadowGroup::minVariance

Increasing this value will decrease possible self-shadowing artifacts but will make shadows fade away.

The default value is safe for most scenes. Increasing the quality field is also preferable before tweaking this value. A special case is for SoVolumeRender node which has a minimum of 0.001 or IVVR_SHADOW_MIN_VARIANCE if set. Default is 1e-5 and range is [0-1].

NOTE: field available since Open Inventor 8.1

Definition at line 312 of file SoShadowGroup.h.

precision

SoSFFloat SoShadowGroup::precision

Specifies the precision of the shadow.

0 = lowest precision, 1 = highest precision. With lower precisions, some parts of the scene may be unlit where they should be lit, or vice versa. Increasing the precision will reduce performance.

NOTE: If your graphics driver does not support the required OpenGL extensions, you may see low precision results even when this field is set to the highest precision.

Definition at line 253 of file SoShadowGroup.h.

quality

SoSFFloat SoShadowGroup::quality

Specifies the quality of the shadow.

The texture used for shadowmap rendering will be of size 2*quality*ViewportSize. Increasing the quality will reduce performance and increase memory consumption.

Definition at line 261 of file SoShadowGroup.h.

shadowCachingEnabled

SoSFBool SoShadowGroup::shadowCachingEnabled

Indicates if a cache should be used for computing the shadows.

Using a cache will improve rendering performance if the lights of your scene and your scene under this group node do not change.

Definition at line 268 of file SoShadowGroup.h.

smoothFactor

SoSFInt32 SoShadowGroup::smoothFactor

Set the smoothness of shadows.

Higher values give smoother shadows. Default is 1.

NOTE: field available since Open Inventor 8.1

Definition at line 300 of file SoShadowGroup.h.

visibilityFlag

SoSFEnum SoShadowGroup::visibilityFlag

Specifies how visibilityRadius is interpreted.

Use enum VisibilityFlag. Default is LONGEST_BBOX_EDGE_FACTOR.

Definition at line 291 of file SoShadowGroup.h.

visibilityRadius

SoSFFloat SoShadowGroup::visibilityRadius

Shadows are only computed within "visibility radius" distance from the camera position.

This radius equals:

• the longest edge of the bounding box of the scene multiplied by visibilityRadius if visibilityFlag equals LONGEST_BBOX_EDGE_FACTOR.
• visibilityRadius if visibilityFlag equals ABSOLUTE_RADIUS.

When visibilityRadius = 1 and visibilityFlag = LONGEST_BBOX_EDGE_FACTOR (default values), shadowing is computed throughout the entire scene.

Note: With VARIANCE_SHADOW_MAP method, try to increase the quality field first.

Definition at line 285 of file SoShadowGroup.h.

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

• Inventor/nodes/SoShadowGroup.h