Added osg::Camera::ProjectionResizePolicy enum and associated methods for controlling

how the field of view is adjust on window resizes.

include/osg/Camera

@@ -123,6 +123,19 @@ class OSG_EXPORT Camera : public Transform, public CullSettings
         /** Get the transformation order.*/
         TransformOrder getTransformOrder() const { return _transformOrder; }
         
+        enum ProjectionResizePolicy
+        {
+            FIXED, /** Keep the projection matrix fixed, despite window resizes.*/
+            HORIZONTAL, /** Adjust the HORIZOTNAL field of view on window resizes.*/
+            VERTICAL /** Adjust the VERTICAL field of view on window resizes.*/
+        };
+        
+        /** Set the policy used to determin if and how the projection matrix should be adjusted on window resizes. */
+        inline void setProjectionResizePolicy(ProjectionResizePolicy policy) { _projectionResizePolicy = policy; }
+
+        /** Get the policy used to determin if and how the projection matrix should be adjusted on window resizes. */
+        inline ProjectionResizePolicy getProjectionResizePolicy() const { return _projectionResizePolicy; }
+
 
         /** Set the projection matrix. Can be thought of as setting the lens of a camera. */
         inline void setProjectionMatrix(const osg::Matrixf& matrix) { _projectionMatrix.set(matrix); }
@@ -417,6 +430,8 @@ class OSG_EXPORT Camera : public Transform, public CullSettings
         ref_ptr<Viewport>           _viewport;
 
         TransformOrder              _transformOrder;
+        ProjectionResizePolicy      _projectionResizePolicy;
+
         Matrixd                     _projectionMatrix;
         Matrixd                     _viewMatrix;