From 559219f519580b81da8497d1b62b5b736cffc1b7 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Thu, 8 Sep 2005 13:10:04 +0000
Subject: [PATCH] Added initial interface for computing intersections between
 sphere segments and terrain.

---
 examples/osgsimulation/osgsimulation.cpp       |  2 +-
 examples/osgspheresegment/osgspheresegment.cpp | 12 ++++++++++++
 include/osgSim/SphereSegment                   |  7 +++++++
 src/osgSim/SphereSegment.cpp                   |  7 +++++++
 4 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/examples/osgsimulation/osgsimulation.cpp b/examples/osgsimulation/osgsimulation.cpp
index 03eec7117..452e3bb63 100644
--- a/examples/osgsimulation/osgsimulation.cpp
+++ b/examples/osgsimulation/osgsimulation.cpp
@@ -323,7 +323,7 @@ int main(int argc, char **argv)
             
             // tell the overlay node to continously update its overlay texture
             // as we know we'll be tracking a moving target.
-            // overlayNode->setContinousUpdate(true);
+            overlayNode->setContinousUpdate(true);
         }
         
         
diff --git a/examples/osgspheresegment/osgspheresegment.cpp b/examples/osgspheresegment/osgspheresegment.cpp
index 4d139ed87..6c9312a88 100644
--- a/examples/osgspheresegment/osgspheresegment.cpp
+++ b/examples/osgspheresegment/osgspheresegment.cpp
@@ -272,6 +272,16 @@ void build_world(osg::Group *root)
         root->addChild(ss.get());
     }
 
+    osgSim::SphereSegment::LineList lines = ss->computeIntersection(terrainGeode.get(), osg::Matrixd::identity());
+    if (!lines.empty())
+    {
+       osg::notify(osg::NOTICE)<<"We've found intersections!!!!"<<std::endl;
+    }
+    else
+    {
+       osg::notify(osg::NOTICE)<<"No intersections found"<<std::endl;
+    }
+
 #if 1
 
 
@@ -285,6 +295,8 @@ void build_world(osg::Group *root)
     overlayNode->addChild(terrainGeode.get());
 
     root->addChild(overlayNode);
+    
+    
 #else
     root->addChild(terrainGeode);
 #endif
diff --git a/include/osgSim/SphereSegment b/include/osgSim/SphereSegment
index 1542c4b45..b759ba841 100644
--- a/include/osgSim/SphereSegment
+++ b/include/osgSim/SphereSegment
@@ -19,6 +19,7 @@
 #include <osg/Vec3>
 #include <osg/Vec4>
 #include <osg/Geode>
+#include <osg/Matrixd>
 #include <osg/BlendFunc>
 
 namespace osgSim{
@@ -226,6 +227,12 @@ public:
     void setAllColors(const osg::Vec4& c);
 
     META_Node(osgSim, SphereSegment);
+    
+    /** A list of vertex arrays representing a list of lines.*/
+    typedef std::vector< osg::ref_ptr<osg::Vec3Array> > LineList;
+    
+    /** Compute the interesection lines between specified geometry and this sphere segment.*/
+    LineList computeIntersection(osg::Node* subgraph, const osg::Matrixd& transform);
 
 private:
 
diff --git a/src/osgSim/SphereSegment.cpp b/src/osgSim/SphereSegment.cpp
index 93c7a18e4..ab596b155 100644
--- a/src/osgSim/SphereSegment.cpp
+++ b/src/osgSim/SphereSegment.cpp
@@ -960,3 +960,10 @@ void SphereSegment::setAllColors(const osg::Vec4& c)
     setEdgeLineColor(c);
     setSideColor(c);
 }
+
+SphereSegment::LineList SphereSegment::computeIntersection(osg::Node* subgraph, const osg::Matrixd& transform)
+{
+    osg::notify(osg::NOTICE)<<"Creating line intersection between sphere segment and subgraph."<<std::endl;
+    SphereSegment::LineList lines;
+    return lines;
+}