From Paul Martz, Introduced osg::OcclusionQueryNode with support for OpenGL occlusion query extension

include/osg/OcclusionQueryNode

@@ -0,0 +1,113 @@
+//
+// Copyright (C) 2007 Skew Matrix Software LLC (http://www.skew-matrix.com)
+//
+// This library is open source and may be redistributed and/or modified under  
+// the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
+// (at your option) any later version.  The full license is in LICENSE file
+// included with this distribution, and on the openscenegraph.org website.
+// 
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
+// OpenSceneGraph Public License for more details.
+//
+
+#ifndef OSG_OCCLUSION_QUERY_NODE
+#define OSG_OCCLUSION_QUERY_NODE 1
+
+#include <osg/Export>
+#include <osg/CopyOp>
+#include <osg/Group>
+
+
+
+namespace osg {
+
+
+// This Node performs occlusion query testing on its children.
+//   You can use it directly to occlusion query test a portion
+//   of your scene graph, or you can use it implicitly with an
+//   OcclusionQueryRoot, which places OcclusionQueryNodes where
+//   needed and acts as a master control.
+class OSG_EXPORT OcclusionQueryNode : public osg::Group
+{
+public:
+    OcclusionQueryNode();
+
+    // Copy constructor using CopyOp to manage deep vs shallow copy.
+    OcclusionQueryNode( const OcclusionQueryNode& oqn, const osg::CopyOp& copyop=osg::CopyOp::SHALLOW_COPY );
+
+    META_Node( osg, OcclusionQueryNode );
+
+    virtual osg::BoundingSphere computeBound() const;
+
+    // When disabled, OQN doesn't perform occlusion queries, and simply
+    //   renders its children.
+    void setQueriesEnabled( bool enable=true );
+    bool getQueriesEnabled() const { return _enabled; }
+
+
+    // Sets/gets the visibility threshold. If the test indicates that
+    //   the number of visible pixels is less than the specified
+    //   threshold, don't draw the actual geometry.
+    void setVisibilityThreshold( unsigned int pixels ) { _visThreshold = pixels; }
+    unsigned int getVisibilityThreshold() const { return _visThreshold; }
+
+    // Specifies how many frames to wait before issuing another query.
+    void setQueryFrameCount( int frames ) { _queryFrameCount = frames; }
+    int getQueryFrameCount() const { return _queryFrameCount; }
+
+    // Indicate whether or not the bounding box used in the occlusion query test
+    //   should be rendered. Handy for debugging and development.
+    // Should only be called outside of cull/draw. No thread issues.
+    void setDebugDisplay( bool enable );
+    bool getDebugDisplay() const;
+
+
+    // Set the StateSets used by the OQN when rendering OQ geometry
+    //   or debug bounding geometry.
+    void setQueryStateSets( osg::StateSet* ss, osg::StateSet* ssDebug );
+
+    // For statistics gathering, e.g., by a NodeVisitor.
+    bool getPassed() const;
+    
+    
+    // These methods are public so that osgUtil::CullVisitor can access them.
+    // Not intended for application use.
+    bool getPassed( const osg::Camera* camera, float distanceToEyePoint );
+    void traverseQuery( const osg::Camera* camera, osg::NodeVisitor& nv );
+    void traverseDebug( osg::NodeVisitor& nv );
+
+protected:
+    virtual ~OcclusionQueryNode();
+
+    void createSupportNodes();
+
+    osg::ref_ptr< osg::Geode > _queryGeode;
+    osg::ref_ptr< osg::Geode > _debugGeode;
+
+    bool _enabled;
+
+    // Tracks the last frame number that we performed a query.
+    // User can set how many times  (See setQueryFrameCount).
+    typedef std::map< const osg::Camera*, int > FrameCountMap;
+    FrameCountMap _frameCountMap;
+    mutable OpenThreads::Mutex _frameCountMutex;
+
+    // For statistics gathering
+    bool _passed;
+
+    // User-settable variables
+    unsigned int _visThreshold;
+    int _queryFrameCount;
+    bool _debugBB;
+
+
+    // Required to ensure that computeBound() is thread-safe.
+    mutable OpenThreads::Mutex _computeBoundMutex;
+};
+
+}
+
+
+#endif