this simple patch will prevent to have fog in Clear cload layers.

diff --git a/simgear/scene/sky/sky.cxx b/simgear/scene/sky/sky.cxx
index 3d446981bdb6c02d2c8aafe34751e1ef08af7964..8e366d3408a0a3380c238f593fa27723e2387489 100644 (file)
--- a/simgear/scene/sky/sky.cxx
+++ b/simgear/scene/sky/sky.cxx
@@ -266,7 +266,10 @@ void SGSky::modify_vis( float alt, float time_factor ) {
 
        double ratio = 1.0;
 
-       if ( alt < asl - transition ) {
+        if ( cloud_layers[i]->getCoverage() == SGCloudLayer::SG_CLOUD_CLEAR ) {
+           // clear layer
+           ratio = 1.0;
+        } else if ( alt < asl - transition ) {
            // below cloud layer
            ratio = 1.0;
        } else if ( alt < asl ) {