Wind effects on vegetation for Atmospheric Light Scattering: movement of trees and hires terrain texture noise simulating vegetation and debris movement

Effects/terrain-default.eff

@@ -104,7 +104,9 @@
     <cloud_self_shading><use>/environment/cloud-self-shading</use></cloud_self_shading>
     <moonlight><use>/environment/moonlight</use></moonlight>
     <season><use>/environment/season</use></season>
-    <windspeed><use>/environment/wind-speed-kt</use></windspeed>
+    <wind_effects><use>/sim/rendering/shaders/wind-effects</use></wind_effects>
+    <windE><use>/environment/sea/surface/wind-from-east-fps</use></windE>
+    <windN><use>/environment/sea/surface/wind-from-north-fps</use></windN>
     <quality_level><use>/sim/rendering/shaders/landmass</use></quality_level>
     <tquality_level><use>/sim/rendering/shaders/transition</use></tquality_level>
   </parameters>
@@ -346,11 +348,6 @@
         <name>wetness</name>
         <type>float</type>
         <value><use>wetness</use></value>
-      </uniform>
-	  <uniform>
-        <name>windspeed</name>
-        <type>float</type>
-        <value><use>windspeed</use></value>
       </uniform>
       <uniform>
         <name>fogstructure</name>
@@ -372,6 +369,16 @@
         <type>float</type>
         <value><use>season</use></value>
       </uniform>
+     <uniform>
+	<name>WindE</name>
+	<type>float</type>
+	<value><use>windE</use></value>
+      </uniform>
+      <uniform>
+	<name>WindN</name>
+	<type>float</type>
+	<value><use>windN</use></value>
+      </uniform>
       <uniform>
         <name>quality_level</name>
         <type>int</type>
@@ -381,6 +388,11 @@
         <name>tquality_level</name>
         <type>int</type>
         <value><use>tquality_level</use></value>
+      </uniform>
+      <uniform>
+      <name>wind_effects</name>
+      <type>int</type>
+      <value><use>wind_effects</use></value>
      </uniform>
       <uniform>
         <name>texture</name>

Effects/tree.eff

@@ -33,6 +33,9 @@
 		<fogtype><use>/sim/rendering/shaders/skydome</use></fogtype>
 		<fogstructure><use>/environment/fog-structure</use></fogstructure>
 		<quality_level><use>/sim/rendering/shaders/landmass</use></quality_level>
+		<wind_effects><use>/sim/rendering/shaders/wind-effects</use></wind_effects>
+		<windE><use>/environment/sea/surface/wind-from-east-fps</use></windE>
+		<windN><use>/environment/sea/surface/wind-from-north-fps</use></windN>
 		<!-- 	END fog include -->
 	</parameters>
 
@@ -135,6 +138,16 @@
         <type>float</type>
         <value><use>season</use></value>
       </uniform>
+      <uniform>
+	<name>WindE</name>
+	<type>float</type>
+	<value><use>windE</use></value>
+      </uniform>
+      <uniform>
+	<name>WindN</name>
+	<type>float</type>
+	<value><use>windN</use></value>
+      </uniform>
       <uniform>
         <name>texture</name>
         <type>sampler-2d</type>
@@ -150,6 +163,11 @@
       <type>int</type>
       <value><use>quality_level</use></value>
      </uniform>
+     <uniform>
+      <name>wind_effects</name>
+      <type>int</type>
+      <value><use>wind_effects</use></value>
+     </uniform>
     </pass>
   </technique>
 	
@@ -257,6 +275,16 @@
         <type>float</type>
         <value><use>season</use></value>
       </uniform>
+     <uniform>
+	<name>WindE</name>
+	<type>float</type>
+	<value><use>windE</use></value>
+      </uniform>
+      <uniform>
+	<name>WindN</name>
+	<type>float</type>
+	<value><use>windN</use></value>
+      </uniform>
       <uniform>
         <name>texture</name>
         <type>sampler-2d</type>
@@ -272,6 +300,11 @@
       <type>int</type>
       <value><use>quality_level</use></value>
      </uniform>
+     <uniform>
+      <name>wind_effects</name>
+      <type>int</type>
+      <value><use>wind_effects</use></value>
+     </uniform>
     </pass>
   </technique>
   	

Shaders/terrain-haze-ultra.frag

@@ -44,7 +44,6 @@ uniform float fogstructure;
 uniform float snow_thickness_factor;
 uniform float cloud_self_shading;
 uniform float season;
-uniform float windspeed;
 uniform float grain_strength;
 uniform float intrinsic_wetness;
 uniform float transition_model;
@@ -52,9 +51,12 @@ uniform float hires_overlay_bias;
 uniform float dot_density;
 uniform float dot_size;
 uniform float dust_resistance;
+uniform float WindE;
+uniform float WindN;
 uniform float osg_SimulationTime;
 uniform int quality_level;
 uniform int tquality_level;
+uniform int wind_effects;
 
 const float EarthRadius = 5800000.0;
 const float terminator_width = 200000.0;
@@ -272,6 +274,34 @@ float msl_altitude = (relPos.z + eye_alt);
     float intensity;
     
 
+
+// Wind motion of the overlay noise simulating movement of vegetation and loose debris
+
+vec2 windPos;
+
+if (wind_effects > 1)
+	{
+	float windSpeed = length(vec2 (WindE,WindN)) /3.0480; 
+	// interfering sine wave wind pattern
+	float sineTerm = sin(0.35 * windSpeed * osg_SimulationTime + 0.05 * (rawPos.x + rawPos.y));
+	sineTerm = sineTerm + sin(0.3 * windSpeed * osg_SimulationTime + 0.04 * (rawPos.x + rawPos.y));
+	sineTerm = sineTerm + sin(0.22 * windSpeed * osg_SimulationTime + 0.05 * (rawPos.x + rawPos.y));
+	sineTerm = sineTerm/3.0;
+	// non-linear amplification to simulate gusts
+	sineTerm = sineTerm * sineTerm;//smoothstep(0.2, 1.0, sineTerm);
+
+	// wind starts moving dust and leaves at around 8 m/s
+	float timeArg = 0.01 * osg_SimulationTime * windSpeed * smoothstep(8.0, 15.0, windSpeed);
+	timeArg = timeArg + 0.02 * sineTerm;
+
+ 	windPos = vec2 (rawPos.x + WindN * timeArg, rawPos.y +  WindE * timeArg);
+	}
+else
+	{
+	windPos = rawPos.xy;
+	}
+
+
 // get noise at different wavelengths
 
 // used:	5m, 5m gradient, 10m, 10m gradient: heightmap of the closeup terrain, 10m also snow
@@ -287,7 +317,7 @@ float noise_10m = Noise2D(rawPos.xy, 10.0);
 float noise_5m = Noise2D(rawPos.xy ,5.0);
 float noise_2m = Noise2D(rawPos.xy ,2.0); 
 float noise_1m = Noise2D(rawPos.xy ,1.0); 
-float noise_01m = Noise2D(rawPos.xy, 0.1);
+float noise_01m = Noise2D(windPos.xy, 0.1);
 
 float noisegrad_10m;
 float noisegrad_5m;
@@ -488,15 +518,7 @@ if ((dist < 5000.0)&& (quality_level > 3) && (combined_wetness>0.0))
 
     texel.rgb = texel.rgb * (1.0 - 0.6 * combined_wetness);
 	
-// surf - terrain is too bad...
+
-/*	foam_texel.rgb =vec3 (1.0, 1.0, 1.0);
-	foam_texel.rg = 0.7 * foam_texel.rg +0.3 * noise_2m * foam_texel.rg;
-	float surf_strength = 1.0 + windspeed/5.0;
-	float surf_sine = sin(osg_SimulationTime+5.0*noise_25m);
-	float surf_steepcorr = 1.0 -smoothstep(0.99,1.01,abs(steepness));
-	float surf_alt = (relPos.z+eye_alt )  - 20.0 * surf_steepcorr ;//+ noise_10m * surf_steepcorr
-	texel.rgb = mix(foam_texel.rgb, texel.rgb, smoothstep((0.3 +0.3*surf_strength+ surf_sine) * surf_steepcorr-20.0, (0.3+ surf_strength + surf_sine) * surf_steepcorr-19.0, surf_alt));
-*/
 
 // light computations
 

Shaders/tree-haze.vert

@@ -18,27 +18,26 @@
 // the surface normal is passed in gl_{Front,Back}Color. The alpha
 // component is set to 1 for front, 0 for back in order to work around
 // bugs with gl_FrontFacing in the fragment shader.
-//varying vec4 diffuse_term;
-//varying vec3 normal;
-varying vec3 relPos;
 
-//varying float earthShade;
+
-//varying float yprime;
+varying vec3 relPos;
-//varying float vertex_alt;
 varying float yprime_alt;
-//varying float mie_angle;
 
 uniform int colorMode;
+uniform int wind_effects;
 uniform float hazeLayerAltitude;
 uniform float terminator;
 uniform float terrain_alt; 
 uniform float avisibility;
 uniform float visibility;
 uniform float overcast;
-//uniform float scattering;
 uniform float ground_scattering;
 uniform float snow_level;
 uniform float season;
+uniform float WindN;
+uniform float WindE;
+
+uniform float osg_SimulationTime;
 
 float earthShade;
 float mie_angle;
@@ -94,6 +93,14 @@ void main()
   // Rotation of the generic quad to specific one for the tree.
   position.xy = vec2(dot(position.xy, vec2(cr, sr)), dot(position.xy, vec2(-sr, cr)));
 
+
+ // Shear by wind.  Note that this only applies to the top vertices    
+  if (wind_effects > 0)           
+  	{
+	position.x = position.x + position.z * (sin(osg_SimulationTime * 1.8 + (gl_Color.x + gl_Color.y + gl_Color.z) * 0.01) + 1.0) * 0.0025 * WindN;
+  	position.y = position.y + position.z * (sin(osg_SimulationTime * 1.8 + (gl_Color.x + gl_Color.y + gl_Color.z) * 0.01) + 1.0) * 0.0025 * WindE;
+	}
+	
   // Move to correct location (stored in gl_Color)
   position = position + gl_Color.xyz;
   gl_Position   = gl_ModelViewProjectionMatrix * vec4(position,1.0);

gui/dialogs/shaders-lightfield.xml

@@ -173,6 +173,30 @@
 		</empty>
 	</group>
 
+	<group>
+		<layout>hbox</layout>
+		<halign>right</halign>
+		<text>
+			<label>Wind Effects</label>
+		</text>
+		<slider>
+			<name>wind</name>
+			<min>0.0</min>
+			<max>2.0</max>
+			<step>1.0</step>
+			<fraction>0.17</fraction>
+			<live>true</live>
+			<property>/sim/rendering/shaders/wind-effects</property>
+			<binding>
+				<command>dialog-apply</command>
+				<object-name>wind</object-name>
+			</binding>
+		</slider>
+		<empty>
+			<pref-width>55</pref-width>
+		</empty>
+	</group>
+	
 	<group>
 		<layout>hbox</layout>
 		<visible>

preferences.xml

@@ -147,6 +147,7 @@ Started September 2000 by David Megginson, david@megginson.com
 				<transition type="float" userarchive="y">1.0</transition>
 				<urban type="float" userarchive="y">1.0</urban>
 				<water type="float" userarchive="y">1.0</water>
+				<wind-effects type="float" userarchive="y">0.0</wind-effects>
 				<lights type="float" userarchive="y">1.0</lights>
 				<quality-level-internal type="float" userarchive="y">1.0</quality-level-internal>
 			</shaders>