230 lines
10 KiB
Plaintext
230 lines
10 KiB
Plaintext
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/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
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*
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* This library is open source and may be redistributed and/or modified under
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* the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
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* (at your option) any later version. The full license is in LICENSE file
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* included with this distribution, and on the openscenegraph.org website.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* OpenSceneGraph Public License for more details.
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*
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* ViewDependentShadow codes Copyright (C) 2008 Wojciech Lewandowski
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* Thanks to to my company http://www.ai.com.pl for allowing me free this work.
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*/
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#ifndef OSGSHADOW_VIEWDEPENDENTSHADOWTECHINIQUE
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#define OSGSHADOW_VIEWDEPENDENTSHADOWTECHINIQUE 1
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#include <osgShadow/ShadowTechnique>
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#include <map>
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#include <osgShadow/Export>
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namespace osgShadow {
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/**
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META_ViewDependentShadowTechniqueData macro defines initViewDependentData
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method used by derived shadow techniques to initialize their specific
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ViewData objects. initViewDependentData will be called from
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ViewDependentShadowTechnique base class to init derived class
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*/
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#define META_ViewDependentShadowTechniqueData( ShadowTechnique, TechniqueData )\
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virtual ViewDependentShadowTechnique::ViewData * initViewDependentData \
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( osgUtil::CullVisitor *cv, ViewDependentShadowTechnique::ViewData * vd ) \
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{ \
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TechniqueData* td = dynamic_cast<TechniqueData*>( vd ); \
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if ( !td ) td = new TechniqueData; \
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td->init( this, cv ); \
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return td; \
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}
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/**
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ViewDependentShadowTechnique is a base class for all
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View Dependent Shadow techniques. It defines fundamental object structure
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and methods to manage separate shadow resources for each view of the scene.
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By view we understand osg::View or SceneView instance and their associated
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Camera. Typical osg application has one or more such views. View Dependent
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Shadow techniques manage shadow generation for them.
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View Dependent Shadow techniques are used to optimize shadow algorithms for
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part of the scene seen on the view. If rest of the scene is behind view
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frustum, there is no sense in computing shadows for it. Since in practice we
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often use 3d databases extending far beyond current camera frustum View
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Dependent Shadow approach may produce much better shadows.
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The other goal is to provide framework for thread safe rendering of
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the shadows. It allows to use shadows with different OSG threading models.
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Conceptually ViewDependentShadowTechnique is similar to osgSim::OverlayNode.
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Its a container class for number of ViewData (or ViewData derived) objects
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doing actual shadow work for each of the scene views.
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But ViewDependentShadowTechnique is intended as foundation layer for all
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derived classes so in some way it extends osgSim::OverlayNode approach a bit.
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HOW IT WORKS:
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ViewDependendentShadowTechnique is derived from osgShadow::ShadowTechnique
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and as such overrides virtual methods of osgShadow::ShadowTechnique.
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But most of the shadow dirty work is done by ViewData objects,
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ViewDependendentShadowTechnique::cull is the only osgShadow::ShadowTechnique
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method where ViewDependendentShadowTechnique does something significant:
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What ViewDependentShadowTechnique::cull( CullVisitor & cv ) does ?
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It identifies View. CullVisitor ptr is used as View identificator.
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In practice we do not check and interpret what are actual Views and SceneViews
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set up by application. We focus on Camera and CullVisitors as a identificators
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of views. We can safely do this because each such view will have associated
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unique CullVisitor used to cull the scene in every frame.
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Based on CullVisitor ptr passed to cull method, associated Technique::ViewData
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object is created (if neccessary) and then seleced. Then control is passed to
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this ViewData object. So, each view has its associated unique ViewData
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(or derived) object performing dirty work of shadow resources management and
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shadow generation for the view.
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To support creation of classes derived from ViewDependentShadowTechnique it
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was neccessary to provide mechanism to override ViewData and allow for
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initialization of new derived ViewData objects. Creation and initialization
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is performed when ViewDependendentShadowTechnique::cull gets called with
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CullVistor ptr which does not yet have associated ViewData object. When it
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happens, virtual initViewDependentData method is called to give
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derived techniques a chance to allocate and iniitalize its specific
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resources as new ViewData derived instance. In practice initViewDependentData
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in derived techniques should look the same as in base class so as a convenience
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it was defined as META_ViewDependentShadowTechnique macro. Derived techniques
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use this macro to override initViewDependentData method for their usage.
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After ViewData derived object is construted and selected, control is passed
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to this object by call to virtual ViewData::cull method. The rest of work
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is the done by this object. ViewDependentShadowTechnique::ViewData is intended
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as a base class so it does nothing. In practice the rest of dirty work will
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do new ViewData classes implemented in derived techniques.
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*/
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class OSGSHADOW_EXPORT ViewDependentShadowTechnique
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: public osgShadow::ShadowTechnique
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{
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public:
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/**
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osgShadow::ShadowTechnique equivalent methods for view dependent techniques
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*/
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/** Classic OSG constructor */
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ViewDependentShadowTechnique( void );
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/** Classic OSG cloning constructor */
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ViewDependentShadowTechnique(
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const ViewDependentShadowTechnique& vdst,
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const osg::CopyOp& copyop=osg::CopyOp::SHALLOW_COPY );
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/** Declaration of standard OSG object methods */
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META_Object( ViewDependentShadow, ViewDependentShadowTechnique );
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/** Dirty view data bits and force update of view data resources */
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virtual void dirty();
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/** Initialize the ShadowedScene and some data structures.*/
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virtual void init();
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/** Run the update traversal of the ShadowedScene and update any local cached data structures.*/
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virtual void update(osg::NodeVisitor& nv);
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/** Run the cull traversal of the ShadowedScene and set up the rendering for this ShadowTechnique.*/
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virtual void cull(osgUtil::CullVisitor& cv);
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/** Clean scene graph from any shadow technique specific nodes, state and drawables.*/
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virtual void cleanSceneGraph();
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/** Traverse shadow scene graph.*/
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virtual void traverse(osg::NodeVisitor& nv);
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protected:
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/** Classic protected OSG destructor */
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~ViewDependentShadowTechnique( void );
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/**
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Base container class for view dependent shadow resources.
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Techniques based on ViewDependentShadowTechnique will usually define
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similar struct and derive it from ViewData to contain their specufic resources.
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*/
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struct ViewData: public osg::Referenced
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{
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/**
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Method called upon ViewData instance to initialize internal variables
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*/
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virtual void init
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( ViewDependentShadowTechnique *st, osgUtil::CullVisitor *cv );
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/**
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Method called by ViewDependentShadowTechnique to allow ViewData
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do the hard work computing shadows for its associated view
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*/
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virtual void cull();
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/**
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Dirty is called by parent ViewDependentShadowTechnique to force
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update of resources after some of them were modified in parent technique
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*/
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virtual void dirty( bool flag );
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/**
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Simple constructor zeroing all variables.
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*/
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ViewData(): _dirty( true ), _cv( NULL ), _st( NULL ) { };
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/**
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Mutex used to guard _dirty flag from override in case when parent technique calls
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dirty() simultaneously with ViewData while it is updating resources inside init method.
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*/
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OpenThreads::Mutex _mutex;
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/**
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View's CullVisitor associated with this ViewData instance
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*/
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osg::observer_ptr< osgUtil::CullVisitor > _cv;
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/**
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Parent ViewDependentShadowTechnique
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*/
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osg::observer_ptr< ViewDependentShadowTechnique > _st;
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/**
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Dirty flag tells this instance to update its resources
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*/
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bool _dirty;
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};
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/**
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Map of view dependent data per view cull visitor (CVs are used as indices)
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ViewDependentShadowTechnique uses this map to find VieData for each cull vitior
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*/
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typedef std::map< osg::ref_ptr< osgUtil::CullVisitor >,
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osg::ref_ptr< ViewData > > ViewDataMap;
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ViewDataMap _viewDataMap;
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/**
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Mutex used to serialize accesses to ViewDataMap
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*/
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OpenThreads::Mutex _viewDataMapMutex;
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/** Return view dependent data for the cull visitor */
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virtual ViewDependentShadowTechnique::ViewData * getViewDependentData( osgUtil::CullVisitor * cv );
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/** Define view dependent data for the cull visitor */
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virtual void setViewDependentData( osgUtil::CullVisitor * cv, ViewDependentShadowTechnique::ViewData * data );
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/**
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Declare standard initViewDependentData method.
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*/
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META_ViewDependentShadowTechniqueData( ViewDependentShadowTechnique, ViewData )
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};
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} // namespace osgShadow
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#endif
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