Provided by: libcoin80-doc_3.1.4~abc9f50-4ubuntu2_all bug

NAME

       SoShadowGroup -

       The SoShadowGroup node is a group node used for shadow rendering.

       Children of this node can recieve shadows, and cast shadows on other children. Use the
       SoShadowStyle node to control shadow casters and shadow receivers.

SYNOPSIS

       #include <FXViz/nodes/SoShadowGroup.h>

       Inherits SoSeparator.

   Public Types
       enum VisibilityFlag { ABSOLUTE_RADIUS, LONGEST_BBOX_EDGE_FACTOR,
           PROJECTED_BBOX_DEPTH_FACTOR }

   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.
       SoShadowGroup (void)
       virtual void GLRenderBelowPath (SoGLRenderAction *action)
       virtual void GLRenderInPath (SoGLRenderAction *action)
       virtual void notify (SoNotList *nl)
       void enableSubgraphSearchOnNotify (const SbBool onoff)

   Static Public Member Functions
       static SoType getClassTypeId (void)
       static void initClass (void)
       static void init (void)
       static SbBool isSupported (void)

   Public Attributes
       SoSFBool isActive
       SoSFFloat intensity
       SoSFFloat precision
       SoSFFloat quality
       SoSFFloat smoothBorder
       SoSFBool shadowCachingEnabled
       SoSFFloat visibilityNearRadius
       SoSFFloat visibilityRadius
       SoSFEnum visibilityFlag
       SoSFFloat epsilon
       SoSFFloat threshold

   Protected Member Functions
       virtual const SoFieldData * getFieldData (void) const
       virtual ~SoShadowGroup ()

   Static Protected Member Functions
       static const SoFieldData ** getFieldDataPtr (void)

   Additional Inherited Members

Detailed Description

       The SoShadowGroup node is a group node used for shadow rendering.

       Children of this node can recieve shadows, and cast shadows on other children. Use the
       SoShadowStyle node to control shadow casters and shadow receivers.

       Please note that all shadow casters will be rendered twice. Once to create the shadow map,
       and once for normal rendering. If you're having performance issues, you should consider
       reducing the number of shadow casters.

       The algorithm used to render the shadows is Variance Shadow Maps
       (http://www.punkuser.net/vsm/). As an extra bonus, all geometry rendered with shadows can
       also be rendered with per fragment phong lighting.

       This node will search its subgraph and calculate shadows for all SoSpotLight nodes. The
       node will use one texture unit for each spot light, so for this node to work 100%, you
       need to have num-spotlights free texture units while rendering the subgraph.

       Currently, we only support scenes with maximum two texture units active while doing shadow
       rendering (unit 0 and unit 1). This is due to the fact that we emulate the OpenGL shading
       model in a shader program, and we're still working on creating a solution that updates the
       shader program during the scene graph traversal. Right now a shader program is created
       when entering the SoShadowGroup node, and this is used for the entire subgraph.

       FILE FORMAT/DEFAULTS:

       SoShadowGroup {
         isActive TRUE
         intensity 0.5
         precision 0.5
         quality 0.5
         shadowCachingEnabled TRUE
         visibilityRadius -1.0
         visibilityFlag LONGEST_BBOX_EDGE_FACTOR

         epsilon 0.00001
         threshold 0.1
         smoothBorder 0.0

       }

       Example scene graph:

       #Inventor V2.1 ascii

       # to get some lighting when headlight is turned off in the viewer
       DirectionalLight { direction 0 0 -1 intensity 0.2 }

       ShadowGroup {
         quality 1 # to get per pixel lighting

         ShadowStyle { style NO_SHADOWING }

         SpotLight {
           location -8 -8 8.0
           direction 1 1 -1
           cutOffAngle 0.35
           dropOffRate 0.7
         }

         ShadowStyle { style CASTS_SHADOW_AND_SHADOWED }

         Separator {
           Complexity { value 1.0 }
           Material { diffuseColor 1 1 0 specularColor 1 1 1 shininess 0.9 }
           Shuttle { translation0 -3 1 0 translation1 3 -5 0 speed 0.25 on TRUE }
           Translation { translation -5 0 2 }
           Sphere { radius 2.0 }
         }

         Separator {
           Material { diffuseColor 1 0 0 specularColor 1 1 1 shininess 0.9 }
           Shuttle { translation0 0 -5 0 translation1 0 5 0 speed 0.15 on TRUE }
           Translation { translation 0 0 -3 }
           Cube { depth 1.8 }
         }
         Separator {
           Material { diffuseColor 0 1 0 specularColor 1 1 1 shininess 0.9 }
           Shuttle { translation0 -5 0 0 translation1 5 0 0 speed 0.3 on TRUE }
           Translation { translation 0 0 -3 }
           Cube { }
         }

         ShadowStyle { style SHADOWED }
         Coordinate3 { point [ -10 -10 -3, 10 -10 -3, 10 10 -3, -10 10 -3 ] }
         Material { specularColor 1 1 1 shininess 0.9 }

         Complexity { textureQuality 0.1 }
         Texture2 { image 2 2 3 0xffffff 0x225588 0x225588 0xffffff }
         Texture2Transform { scaleFactor 4 4 }
         FaceSet { numVertices 4 }
       }

       Since:
           Coin 2.5

Constructor & Destructor Documentation

   SoShadowGroup::SoShadowGroup (void)
       Default constructor.

   SoShadowGroup::~SoShadowGroup () [protected],  [virtual]
       Destructor.

Member Function Documentation

   SoType SoShadowGroup::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.

       Reimplemented from SoSeparator.

   const SoFieldData * SoShadowGroup::getFieldData (void) const [protected],  [virtual]
       Returns a pointer to the class-wide field data storage object for this instance. If no
       fields are present, returns NULL.

       Reimplemented from SoSeparator.

   SbBool SoShadowGroup::isSupported (void) [static]
       Reports whether or not the shadow nodes can be used successfully on the current system.

       The result will depend on the specific qualities of the graphics card and OpenGL driver on
       the system.

       An important note about this function:

       The API design of this function has a serious shortcoming, as features of OpenGL should be
       tested within an OpenGL context, and this function does not provide any means of
       specifying the context. It is implemented in this manner to match the function signature
       in TGS Inventor, for compatibility reasons.

       (A temporary offscreen OpenGL context is set up for the feature tests. This should usually
       be sufficient to decide whether or not the graphics driver / card supports the features
       needed for rendering shadows.)

       Since:
           Coin 3.1

   void SoShadowGroup::GLRenderBelowPath (SoGLRenderAction *action) [virtual]
       SGI Open Inventor v2.1 obsoleted support for SoGLRenderAction::addMethod(). Instead,
       GLRender() might be called directly, and to optimize traversal, the SoSeparator node calls
       GLRenderBelowPath whenever the path code is BELOW_PATH or NO_PATH (path code is guaranteed
       not to change). To be compatible with SGI's Inventor (and thereby also TGS') we have
       chosen to follow their implementation in this respect.

       SoSeparator::GLRenderBelowPath() do not traverse its children using
       SoChildList::traverse(), but calls GLRenderBelowPath() directly for all its children.

       Reimplemented from SoSeparator.

   void SoShadowGroup::GLRenderInPath (SoGLRenderAction *action) [virtual]
       Implements the SoAction::IN_PATH traversal method for the rendering action.

       Reimplemented from SoSeparator.

   void SoShadowGroup::notify (SoNotList *l) [virtual]
       Notifies all auditors for this instance when changes are made.

       Reimplemented from SoSeparator.

   void SoShadowGroup::enableSubgraphSearchOnNotify (const SbBoolonoff)
       By default, the SoShadowGroup node will search its subgraph for new spot lights whenever a
       group node under it is touched. However, this might lead to bad performance in some cases
       so it's possible to disable this feature using this method. If you do disable this
       feature, make sure you enable it again before inserting a new spot light, or insert all
       spot lights in the scene graph before you render the scene once, and just set 'on' to
       FALSE if you want to toggle spot lights on/off on the fly.

       Since:
           Coin 2.6

Member Data Documentation

   SoSFBool SoShadowGroup::isActive
       Use this field to turn shadow rendering for the subgraph on/off. Default value is TRUE.

   SoSFFloat SoShadowGroup::intensity
       Not used yet. Provided for TGS Inventor compatibility.

   SoSFFloat SoShadowGroup::precision
       Use to calculate the size of the shadow map. A precision of 1.0 means the maximum shadow
       buffer size will be used (typically 2048x2048 on current graphics cards). Default value is
       0.5.

   SoSFFloat SoShadowGroup::quality
       Can be used to tune the shader program complexity. A higher value will mean that more
       calculations are done per-fragment instead of per-vertex. Default value is 0.5.

   SoSFInt32 SoShadowGroup::smoothBorder
       SoShadowGroup::VisibilityFlag SoShadowGroup::ABSOLUTE_RADIUS

       The absolute values of visibilityNearRadius and visibilityRadius will be used.

       SoShadowGroup::VisibilityFlag SoShadowGroup::LONGEST_BBOX_EDGE_FACTOR

       The longest bbox edge will be used to determine near and far clipping planes.

       SoShadowGroup::VisibilityFlag SoShadowGroup::PROJECTED_BBOX_DEPTH_FACTOR

       The bbox depth (projected to face the camera) will be used to calculate the clipping
       planes.

       We have some problems with this feature so it's not supported at the moment.

       Used to add shadow border smoothing. This is currently done as a post processing step on
       the shadow map. The algorithm used is Gauss Smoothing, but in the future we'll probably
       change this, and use a summed area sampling merhod instead. The value should be a number
       between 0 (no smoothing), and 1 (max smoothing).

       If you want to enable smoothing, choosing a low value (~0.1) works best in the current
       implementation.

       Default value is 0.0.

   SoSFBool SoShadowGroup::shadowCachingEnabled
       Not used yet. Provided for TGS Inventor compatibility.

   SoSFFloat SoShadowGroup::visibilityNearRadius
       Can be used to manually set the near clipping plane of the shadow maps. If a negative
       value is provided, the group will calculate a near plane based on the bounding box of the
       children. Default value is -1.0.

       See Also:
           visibilityFlag

   SoSFFloat SoShadowGroup::visibilityRadius
       Can be used to manually set the far clipping plane of the shadow maps. If a negative value
       is provided, the group will calculate a near plane based on the bounding box of the
       children. Default value is -1.0.

       See Also:
           visibilityFlag

   SoSFEnum SoShadowGroup::visibilityFlag
       Determines how visibilityRadius and visibilitNearRadius is used to calculate near and far
       clipping planes for the shadow volume.

   SoSFFloat SoShadowGroup::epsilon
       Epsilon is used to offset the shadow map depth from the model depth. Should be set to as
       low a number as possible without causing flickering in the shadows or on non-shadowed
       objects. Default value is 0.00001.

   SoSFFloat SoShadowGroup::threshold
       Can be used to avoid light bleeding in merged shadows cast from different objects.

       A threshold to completely eliminate all light bleeding can be computed from the ratio of
       overlapping occluder distances from the light's perspective. See
       http://forum.beyond3d.com/showthread.php?t=38165 for a discussion about this problem.

Author

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