Create a new attribute to set the max visibility range to separate the time when the tiles are streamed from the time when the tiles are visible

Author: JeromeDesfieux

src/osgEarthFeatures/FeatureDisplayLayout

@@ -53,6 +53,9 @@ namespace osgEarth { namespace Features
         optional<float>& maxRange() { return _maxRange; }
         const optional<float>& maxRange() const { return _maxRange; }
 
+        optional<float>& maxVisibilityRange() { return _maxVisibilityRange; }
+        const optional<float>& maxVisibilityRange() const { return _maxVisibilityRange; }
+
         /** Style class (or style selector) name associated with this level (optional) */
         optional<std::string>& styleName() { return _styleName; }
         const optional<std::string>& styleName() const { return _styleName; }
@@ -69,6 +72,7 @@ namespace osgEarth { namespace Features
 
         optional<float>       _minRange;
         optional<float>       _maxRange;
+        optional<float>       _maxVisibilityRange;
         optional<std::string> _styleName;
     };
 

src/osgEarthFeatures/FeatureDisplayLayout.cpp

@@ -27,7 +27,8 @@ using namespace osgEarth::Symbology;
 
 FeatureLevel::FeatureLevel( const Config& conf ) :
 _minRange( 0.0f ),
-_maxRange( FLT_MAX )
+_maxRange( FLT_MAX ),
+_maxVisibilityRange( FLT_MAX)
 {
     fromConfig( conf );
 }
@@ -50,6 +51,7 @@ FeatureLevel::fromConfig( const Config& conf )
 {
     conf.getIfSet( "min_range", _minRange );
     conf.getIfSet( "max_range", _maxRange );
+    conf.getIfSet( "max_visibility_range", _maxVisibilityRange );
     conf.getIfSet( "style",     _styleName ); 
     conf.getIfSet( "class",     _styleName ); // alias
 }
@@ -60,6 +62,7 @@ FeatureLevel::getConfig() const
     Config conf( "level" );
     conf.addIfSet( "min_range", _minRange );
     conf.addIfSet( "max_range", _maxRange );
+    conf.addIfSet( "max_visibility_range", _maxVisibilityRange );
     conf.addIfSet( "style",     _styleName );
     return conf;
 }