Changeset 11127 for OpenSceneGraph/trunk/src/osg/OcclusionQueryNode.cpp

Timestamp:

02/26/10 11:13:28 (3 years ago)

Author:

robert

Message:

From Paul Martz, "The changes are very similar to Magne's, except they now take the near plane into account. The changes are:

• Change OcclusionQueryNode::getPassed to take a NodeVisitor? rather than the distance from BS center to the eye point. Change where CullVisitor? calls this method to use the new parameters.
  
• getPassed now exits early and returns true to avoid blinking / blink-in of geometry for the first frame or for out-of-range LOD children coming back into view.
  
• getPassed now considers the distance from the near plane to the bounding sphere (rather than eye point to bounding sphere) when determining if the viewer is "inside" the bounding sphere or not."
  

Files:

• OpenSceneGraph/trunk/src/osg/OcclusionQueryNode.cpp (modified) (3 diffs)

OpenSceneGraph/trunk/src/osg/OcclusionQueryNode.cpp

@@ -553 +553 @@
 
 bool
-OcclusionQueryNode::getPassed( const osg::Camera* camera, float distanceToEyePoint )
+OcclusionQueryNode::getPassed( const osg::Camera* camera, osg::NodeVisitor& nv )
 {
     if ( !_enabled )
@@ -560 +560 @@
         return true;
 
+    {
+        // Two situations where we want to simply do a regular traversal:
+        //  1) it's the first frame for this camers
+        //  2) we haven't rendered for an abnormally long time (probably because we're an out-of-range LOD child)
+        // In these cases, assume we're visible to avoid blinking.
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock( _frameCountMutex );
+        const int& lastQueryFrame( _frameCountMap[ camera ] );
+        if( ( lastQueryFrame == 0 ) ||
+            ( (nv.getTraversalNumber() - lastQueryFrame) >  (_queryFrameCount + 1) ) )
+            return true;
+    }
+
     if (_queryGeode->getDrawable( 0 ) == NULL)
     {
@@ -569 +581 @@
     QueryGeometry* qg = static_cast< QueryGeometry* >( _queryGeode->getDrawable( 0 ) );
 
-    // If the distance to the bounding sphere shell is positive, retrieve
-    //   the results. Others (we're inside the BS shell) we are considered
+    // Get the near plane for the upcoming distance calculation.
+    float nearPlane;
+    const osg::Matrix& proj( camera->getProjectionMatrix() );
+    if( ( proj(3,3) != 1. ) || ( proj(2,3) != 0. ) || ( proj(1,3) != 0. ) || ( proj(0,3) != 0.) )
+        nearPlane = proj(3,2) / (proj(2,2)-1.);  // frustum / perspective
+    else
+        nearPlane = (proj(3,2)+1.) / proj(2,2);  // ortho
+
+    // If the distance from the near plane to the bounding sphere shell is positive, retrieve
+    //   the results. Otherwise (near plane inside the BS shell) we are considered
     //   to have passed and don't need to retrieve the query.
     const osg::BoundingSphere& bs = getBound();
-    float distance = distanceToEyePoint  - bs._radius;
+    float distanceToEyePoint = nv.getDistanceToEyePoint( bs._center, false );
+
+    float distance = distanceToEyePoint - nearPlane - bs._radius;
     _passed = ( distance <= 0.f );
     if (!_passed)