Bugfix: Terrain quality taken into account in model shaders.

Objects like OSM buildings using the `model-combined` effect ignored
the Terrain quality. Rayleigh Fog is computed for the terrain only
at "Ultra" level, but was computed for models at all quality levels,
which led to a visual disparity. The shader now takes into account
the terrain quality before computing rayleigh fog for objects.
The `road` effect also had the same issue and is fixed now.

Effects/model-combined.eff

@@ -194,6 +194,8 @@ please see Docs/README.model-combined.eff for documentation
 		<cloudpos20_y><use>/local-weather/cloud-shadows/cloudpos-y[19]</use></cloudpos20_y>
 		<cloud_shadow_flag><use>/local-weather/cloud-shadows/cloud-shadow-flag</use></cloud_shadow_flag>
 		<building-flag type="int">0</building-flag>
+		<quality_level><use>/sim/rendering/shaders/landmass</use></quality_level>
+		<tquality_level><use>/sim/rendering/shaders/transition</use></tquality_level>
 		<!-- 		END fog include -->
 	</parameters>
 
@@ -1026,6 +1028,17 @@ please see Docs/README.model-combined.eff for documentation
 				<value><use>fact_black</use></value>
 			   </uniform>
 
+			   <uniform>
+				<name>quality_level</name>
+				<type>int</type>
+				<value><use>quality_level</use></value>
+			   </uniform>
+			   <uniform>
+				<name>tquality_level</name>
+				<type>int</type>
+				<value><use>tquality_level</use></value>
+			   </uniform>
+
 			  <!-- cloud shadows -->
  			   <uniform>
        				  <name>cloudpos1_x</name>
@@ -1268,7 +1281,6 @@ please see Docs/README.model-combined.eff for documentation
 				  <value><use>building-flag</use></value>
      			   </uniform>
 
-
 		           <!-- 			END fog include -->
                    <!-- BEGIN shadows include -->
                    <uniform>

Effects/road.eff

@@ -840,6 +840,17 @@
 				<value><use>fact_black</use></value>
 			   </uniform>
 
+			   <uniform>
+				<name>quality_level</name>
+				<type>int</type>
+				<value><use>quality_level</use></value>
+			   </uniform>
+			   <uniform>
+				<name>tquality_level</name>
+				<type>int</type>
+				<value><use>tquality_level</use></value>
+			   </uniform>
+
 			  <!-- cloud shadows -->
  			   <uniform>
        				  <name>cloudpos1_x</name>

Shaders/model-ALS-ultra.frag

@@ -79,6 +79,9 @@ uniform float air_pollution;
 uniform float snowlevel;
 uniform float snow_thickness_factor;
 
+uniform int quality_level;
+uniform int tquality_level;
+
 uniform float osg_SimulationTime;
 uniform mat4 osg_ViewMatrix;
 
@@ -660,7 +663,9 @@ void main (void)
     	//hazeColor = clamp(hazeColor, 0.0, 1.0);
 
     ///BEGIN Rayleigh fog ///
-
+    // Only compute fog if terrain level is 'Ultra'
+    if ((quality_level > 5) && (tquality_level > 5))
+    {
     	// Rayleigh color shift due to out-scattering
     	float rayleigh_length = 0.5 * avisibility * (2.5 - 1.9 * air_pollution)/alt_factor(eye_alt, eye_alt+relPos.z);
     	float outscatter = 1.0-exp(-dist/rayleigh_length);
@@ -669,7 +674,7 @@ void main (void)
 	vec3 rayleighColor = vec3 (0.17, 0.52, 0.87) * lightIntensity;
    	float rayleighStrength = rayleigh_in_func(dist, air_pollution, avisibility/max(lightIntensity,0.05), eye_alt, eye_alt + relPos.z);
   	fragColor.rgb = mix(fragColor.rgb, rayleighColor,rayleighStrength);
-
+    }
     /// END Rayleigh fog
 
     // don't let the light fade out too rapidly

Shaders/road-ALS-ultra.frag

@@ -76,6 +76,9 @@ uniform float air_pollution;
 uniform float snowlevel;
 uniform float snow_thickness_factor;
 
+uniform int quality_level;
+uniform int tquality_level;
+
 uniform float osg_SimulationTime;
 
 uniform float landing_light1_offset;
@@ -842,7 +845,9 @@ void main (void)
     	hazeColor = clamp(hazeColor, 0.0, 1.0);
 
     ///BEGIN Rayleigh fog ///
-
+    // Only compute fog if terrain level is 'Ultra'
+    if ((quality_level > 5) && (tquality_level > 5))
+    {
     	// Rayleigh color shift due to out-scattering
     	float rayleigh_length = 0.5 * avisibility * (2.5 - 1.9 * air_pollution)/alt_factor(eye_alt, eye_alt+relPos.z);
     	float outscatter = 1.0-exp(-dist/rayleigh_length);
@@ -851,7 +856,7 @@ void main (void)
 	vec3 rayleighColor = vec3 (0.17, 0.52, 0.87) * lightIntensity;
    	float rayleighStrength = rayleigh_in_func(dist, air_pollution, avisibility/max(lightIntensity,0.05), eye_alt, eye_alt + relPos.z);
   	fragColor.rgb = mix(fragColor.rgb, rayleighColor,rayleighStrength);
-
+    }
     /// END Rayleigh fog
 
     // don't let the light fade out too rapidly