From Chris Hanson:

Spelling fixes in include/osg/LOD

   Negated priority in PagedLOD when using _rangeMode==PIXEL_SIZE_ON_SCREEN

   Added clampedPixelSize() methods to CullStack and CullingSet to return fabs()ed values.

   Changed LOD and PagedLOD ::traverse to use clampedPixelSize() methods.

include/osg/CullStack

@@ -65,6 +65,18 @@ class OSG_EXPORT CullStack : public osg::CullSettings
             return pixelSize(bs.center(),bs.radius());
         }
 
+        /** Compute the pixel size of an object at position v, with specified radius. fabs()ed to always be positive. */
+        float clampedPixelSize(const Vec3& v,float radius) const
+        {
+            return getCurrentCullingSet().clampedPixelSize(v,radius);
+        }
+        
+        /** Compute the pixel size of the bounding sphere. fabs()ed to always be positive. */
+        float clampedPixelSize(const BoundingSphere& bs) const
+        {
+            return clampedPixelSize(bs.center(),bs.radius());
+        }
+
         inline void disableAndPushOccludersCurrentMask(NodePath& nodePath)
         {
             getCurrentCullingSet().disableAndPushOccludersCurrentMask(nodePath);

include/osg/CullingSet

@@ -18,6 +18,8 @@
 #include <osg/ShadowVolumeOccluder>
 #include <osg/Referenced>
 
+#include <math.h>
+
 
 namespace osg {
 
@@ -172,6 +174,12 @@ class OSG_EXPORT CullingSet : public Referenced
         /** Compute the pixel of a bounding sphere.*/
         float pixelSize(const BoundingSphere& bs) const { return bs.radius()/(bs.center()*_pixelSizeVector); }
 
+        /** Compute the pixel of an object at position v, with specified radius. fabs()ed to always be positive. */
+        float clampedPixelSize(const Vec3& v,float radius) const { return fabs(pixelSize(v, radius)); }
+
+        /** Compute the pixel of a bounding sphere. fabs()ed to always be positive. */
+        float clampedPixelSize(const BoundingSphere& bs) const { return fabs(pixelSize(bs)); }
+
 
         inline bool isCulled(const std::vector<Vec3>& vertices)
         {

include/osg/LOD

@@ -55,17 +55,17 @@ class OSG_EXPORT LOD : public Group
         typedef std::pair<float,float>  MinMaxPair;
         typedef std::vector<MinMaxPair> RangeList;
       
-        /** Modes which control how the center of object should be determined when computed which child is active.*/
+        /** Modes which control how the center of object should be determined when computing which child is active.*/
         enum CenterMode
         {
             USE_BOUNDING_SPHERE_CENTER,
             USER_DEFINED_CENTER
         };
 
-        /** Set how the center of object should be determined when computed which child is active.*/
+        /** Set how the center of object should be determined when computing which child is active.*/
         void setCenterMode(CenterMode mode) { _centerMode=mode; }
 
-        /** Get how the center of object should be determined when computed which child is active.*/
+        /** Get how the center of object should be determined when computing which child is active.*/
         CenterMode getCenterMode() const { return _centerMode; }
 
         /** Sets the object-space point which defines the center of the osg::LOD.  

src/osg/LOD.cpp

@@ -54,7 +54,7 @@ void LOD::traverse(NodeVisitor& nv)
                 osg::CullStack* cullStack = dynamic_cast<osg::CullStack*>(&nv);
                 if (cullStack)
                 {
-                    required_range = cullStack->pixelSize(getBound());
+                    required_range = cullStack->clampedPixelSize(getBound());
                 }
                 else
                 {
@@ -104,7 +104,7 @@ bool LOD::addChild( Node *child )
         if (_children.size()>_rangeList.size()) 
         {
             float maxRange = !_rangeList.empty()?
-                 _rangeList.back().second : 0.0f;
+                 maxRange=_rangeList.back().second : 0.0f;
 
             _rangeList.resize(_children.size(),MinMaxPair(maxRange,maxRange));
         }

src/osg/PagedLOD.cpp

@@ -126,7 +126,7 @@ void PagedLOD::traverse(NodeVisitor& nv)
                 osg::CullStack* cullStack = dynamic_cast<osg::CullStack*>(&nv);
                 if (cullStack)
                 {
-                    required_range = cullStack->pixelSize(getBound());
+                    required_range = cullStack->clampedPixelSize(getBound());
                 }
                 else
                 {
@@ -170,12 +170,18 @@ void PagedLOD::traverse(NodeVisitor& nv)
                     _children[numChildren-1]->accept(nv);
                 }
                 
-                // now request the loading of the next unload child.
+                // now request the loading of the next unloaded child.
                 if (nv.getDatabaseRequestHandler() && numChildren<_perRangeDataList.size())
                 {
                     // compute priority from where abouts in the required range the distance falls.
                     float priority = (_rangeList[numChildren].second-required_range)/(_rangeList[numChildren].second-_rangeList[numChildren].first);
                     
+                    // invert priority for PIXEL_SIZE_ON_SCREEN mode
+                    if(_rangeMode==PIXEL_SIZE_ON_SCREEN)
+                    {
+                        priority = -priority;
+                    }
+                    
                     // modify the priority according to the child's priority offset and scale.
                     priority = _perRangeDataList[numChildren]._priorityOffset + priority * _perRangeDataList[numChildren]._priorityScale;
                     
@@ -185,7 +191,7 @@ void PagedLOD::traverse(NodeVisitor& nv)
                     }
                     else
                     {
-                        // prepend the databasePath to the childs filename.
+                        // prepend the databasePath to the child's filename.
                         nv.getDatabaseRequestHandler()->requestNodeFile(_databasePath+_perRangeDataList[numChildren]._filename,this,priority,nv.getFrameStamp());
                     }
                 }