From 1e0af3590094905a59a7a5cf172e375e4a908729 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Tue, 15 May 2007 17:04:57 +0000
Subject: [PATCH] Added code to better compute the view frustum that is
 appropriate for a traversed subgraph.

---
 include/osgUtil/CullVisitor |  5 +++
 src/osgSim/OverlayNode.cpp  | 76 +++++++++++++++++++++++++++++++++++--
 src/osgUtil/CullVisitor.cpp | 14 +++++--
 3 files changed, 88 insertions(+), 7 deletions(-)

diff --git a/include/osgUtil/CullVisitor b/include/osgUtil/CullVisitor
index a51951d6f..cf1c4eb67 100644
--- a/include/osgUtil/CullVisitor
+++ b/include/osgUtil/CullVisitor
@@ -188,6 +188,11 @@ class OSGUTIL_EXPORT CullVisitor : public osg::NodeVisitor, public osg::CullStac
         /** Add an attribute which is positioned relative to the modelview matrix.*/
         inline void addPositionedTextureAttribute(unsigned int textureUnit, osg::RefMatrix* matrix,const osg::StateAttribute* attr);
 
+
+        /** compute near plane based on the polgon intersection of primtives in near plane candidate list of drawables.
+          * Note, you have to set ComputeNearFarMode to COMPUTE_NEAR_FAR_USING_PRIMITIVES to be able to near plane candidate drawables to be recorded by the cull traversal. */ 
+        void computeNearPlane();
+
         /** Re-implement CullStack's popProjectionMatrix() adding clamping of the projection matrix to
           * the computed near and far.*/
         virtual void popProjectionMatrix();
diff --git a/src/osgSim/OverlayNode.cpp b/src/osgSim/OverlayNode.cpp
index e8990626e..194025310 100644
--- a/src/osgSim/OverlayNode.cpp
+++ b/src/osgSim/OverlayNode.cpp
@@ -11,6 +11,7 @@
  * OpenSceneGraph Public License for more details.
 */
 
+#include <osg/ComputeBoundsVisitor>
 #include <osg/Texture2D>
 #include <osg/CoordinateSystemNode>
 #include <osg/TexEnv>
@@ -337,7 +338,7 @@ void OverlayNode::traverse_OBJECT_DEPENDENT_WITH_ORTHOGRAPHIC_OVERLAY(osg::NodeV
 
 void OverlayNode::traverse_VIEW_DEPENDENT_WITH_ORTHOGRAPHIC_OVERLAY(osg::NodeVisitor& nv)
 {
-    osg::notify(osg::NOTICE)<<"OverlayNode::traverse() - VIEW_DEPENDENT_WITH_ORTHOGRAPHIC_OVERLAY"<<std::endl;
+    // osg::notify(osg::NOTICE)<<"OverlayNode::traverse() - VIEW_DEPENDENT_WITH_ORTHOGRAPHIC_OVERLAY"<<std::endl;
 
 
     if (nv.getVisitorType() != osg::NodeVisitor::CULL_VISITOR)
@@ -355,9 +356,78 @@ void OverlayNode::traverse_VIEW_DEPENDENT_WITH_ORTHOGRAPHIC_OVERLAY(osg::NodeVis
     
     OverlayData& overlayData = getOverlayData(cv);
 
-    Group::traverse(nv);
+    if (_overlaySubgraph.valid()) 
+    {
+        // get the bounds of the model.    
+        osg::ComputeBoundsVisitor cbbv(osg::NodeVisitor::TRAVERSE_ACTIVE_CHILDREN);
+        _overlaySubgraph->accept(cbbv);
+        
+        Group::traverse(nv);    
 
-    osg::notify(osg::NOTICE)<<"   "<<&overlayData<<std::endl;
+        osg::Matrix pm = *(cv->getProjectionMatrix());
+        
+        osgUtil::CullVisitor::value_type znear = cv->getCalculatedNearPlane();
+        osgUtil::CullVisitor::value_type zfar = cv->getCalculatedFarPlane();
+        
+        // osg::notify(osg::NOTICE)<<" before znear ="<<znear<<"\t zfar ="<<zfar<<std::endl;
+        
+        cv->computeNearPlane();
+        
+        znear = cv->getCalculatedNearPlane();
+        zfar = cv->getCalculatedFarPlane();
+
+        // osg::notify(osg::NOTICE)<<" after znear ="<<znear<<"\t zfar ="<<zfar<<std::endl;
+
+        // osg::notify(osg::NOTICE)<<" before clamp pm="<<pm<<std::endl;
+
+        cv->clampProjectionMatrixImplementation(pm, znear,zfar);
+        
+        // osg::notify(osg::NOTICE)<<" after clamp pm="<<pm<<std::endl;
+        
+        osg::Matrix MVP = *(cv->getModelViewMatrix()) * pm;
+        osg::Matrix inverseMVP;
+        inverseMVP.invert(MVP);
+        
+        // osg::notify(osg::NOTICE)<<" MVP="<<MVP<<std::endl;
+        // osg::notify(osg::NOTICE)<<" inverseMVP="<<inverseMVP<<std::endl;
+        
+        typedef std::vector<osg::Vec3d> Corners;
+        Corners corners;
+        corners.push_back(osg::Vec3d(-1.0,-1.0,-1.0));
+        corners.push_back(osg::Vec3d(1.0,-1.0,-1.0));
+        corners.push_back(osg::Vec3d(1.0,1.0,-1.0));
+        corners.push_back(osg::Vec3d(-1.0,1.0,1.0));
+        corners.push_back(osg::Vec3d(-1.0,-1.0,1.0));
+        corners.push_back(osg::Vec3d(1.0,-1.0,1.0));
+        corners.push_back(osg::Vec3d(1.0,1.0,1.0));
+        corners.push_back(osg::Vec3d(-1.0,1.0,1.0));
+        
+        
+        osg::Vec3d center;
+        for(Corners::iterator itr = corners.begin();
+            itr != corners.end();
+            ++itr)
+        {
+            *itr = *itr * inverseMVP;
+            center += *itr;
+            // osg::notify(osg::NOTICE)<<"    corner ="<<*itr<<std::endl;
+        }
+        
+        center /= 8.0;
+        
+        double diagonal = (corners[0]-corners[7]).length();
+        
+        osg::notify(osg::NOTICE)<<"    center ="<<center<<" diagonal ="<<diagonal<<std::endl;
+        
+
+    }
+    else
+    {
+        Group::traverse(nv);    
+    }
+    
+
+    // osg::notify(osg::NOTICE)<<"   "<<&overlayData<<std::endl;
 }
 
 void OverlayNode::traverse_VIEW_DEPENDENT_WITH_PERSPECTIVE_OVERLAY(osg::NodeVisitor& nv)
diff --git a/src/osgUtil/CullVisitor.cpp b/src/osgUtil/CullVisitor.cpp
index 2ea7caf43..665bd2773 100644
--- a/src/osgUtil/CullVisitor.cpp
+++ b/src/osgUtil/CullVisitor.cpp
@@ -173,13 +173,12 @@ float CullVisitor::getDistanceFromEyePoint(const osg::Vec3& pos, bool withLODSca
     else return dist;
 }
 
-void CullVisitor::popProjectionMatrix()
+void CullVisitor::computeNearPlane()
 {
-
     if (!_nearPlaneCandidateMap.empty())
     { 
     
-        // osg::Timer_t start_t = osg::Timer::instance()->tick();
+        osg::Timer_t start_t = osg::Timer::instance()->tick();
         
         // update near from defferred list of drawables
         unsigned int numTests = 0;
@@ -197,9 +196,16 @@ void CullVisitor::popProjectionMatrix()
             }
         } 
 
-        // osg::Timer_t end_t = osg::Timer::instance()->tick();
+        osg::Timer_t end_t = osg::Timer::instance()->tick();
         // osg::notify(osg::NOTICE)<<"Took "<<osg::Timer::instance()->delta_m(start_t,end_t)<<"ms to test "<<numTests<<" out of "<<_nearPlaneCandidateMap.size()<<std::endl;
+
+        _nearPlaneCandidateMap.clear();
     }
+}
+
+void CullVisitor::popProjectionMatrix()
+{
+    computeNearPlane();
 
     if (_computeNearFar && _computed_zfar>=_computed_znear)
     {