Added new Transform::ReferenceType enum ABSOLUTE_RF_INHERIT_VIEWPOINT to support

internal RTT cameras that wish to use the main cameras view/eye point for LOD and other
distance based tests.

include/osg/CullStack

@@ -18,6 +18,7 @@
 #include <osg/CullSettings>
 #include <osg/Viewport>
 #include <osg/fast_back_stack>
+#include <osg/Transform>
 
 namespace osg {
 
@@ -47,7 +48,7 @@ class OSG_EXPORT CullStack : public osg::CullSettings
         void pushProjectionMatrix(osg::RefMatrix* matrix);
         void popProjectionMatrix();
 
-        void pushModelViewMatrix(osg::RefMatrix* matrix);
+        void pushModelViewMatrix(osg::RefMatrix* matrix, Transform::ReferenceFrame referenceFrame);
         void popModelViewMatrix();
 
         inline float getFrustumVolume() { if (_frustumVolume<0.0f) computeFrustumVolume(); return _frustumVolume; }

include/osg/Transform

@@ -90,7 +90,8 @@ class OSG_EXPORT Transform : public Group
         enum ReferenceFrame
         {
             RELATIVE_RF,
-            ABSOLUTE_RF
+            ABSOLUTE_RF,
+            ABSOLUTE_RF_INHERIT_VIEWPOINT
         };
         
         /** Set the transform's ReferenceFrame, either to be relative to its
@@ -104,6 +105,12 @@ class OSG_EXPORT Transform : public Group
           * deep in the scene graph.  It is therefore recommended to only use
           * absolute Transforms at the top of the scene, for such things as
           * heads up displays.
+          * ABSOLUTE_RF_INHERIT_VIEWPOINT is the same as ABSOLUTE_RF except it
+          * adds the ability to use the parents view points position in world coordinates
+          * as its local viewpoint in the new coordinates frame.  This is useful for
+          * Render to texture Cameras that wish to use the main views LOD range computation 
+          * (which uses the viewpoint rather than the eye point) rather than use the local
+          * eye point defined by the this Transforms' abosolute view matrix.
         */
         void setReferenceFrame(ReferenceFrame rf);