SL-1289

add cloud_variance control for randomized perturbance of clouds to break up tiling monotony

12 files changed, 116 insertions, 37 deletions

diff --git a/indra/llinventory/llsettingssky.cpp b/indra/llinventory/llsettingssky.cpp
index dd3a76be31..5ef964af04 100644
--- a/indra/llinventory/llsettingssky.cpp
+++ b/indra/llinventory/llsettingssky.cpp
@@ -91,6 +91,7 @@ const std::string LLSettingsSky::SETTING_CLOUD_SCALE("cloud_scale");
 const std::string LLSettingsSky::SETTING_CLOUD_SCROLL_RATE("cloud_scroll_rate");
 const std::string LLSettingsSky::SETTING_CLOUD_SHADOW("cloud_shadow");
 const std::string LLSettingsSky::SETTING_CLOUD_TEXTUREID("cloud_id");
+const std::string LLSettingsSky::SETTING_CLOUD_VARIANCE("cloud_variance");
 
 const std::string LLSettingsSky::SETTING_DOME_OFFSET("dome_offset");
 const std::string LLSettingsSky::SETTING_DOME_RADIUS("dome_radius");
@@ -539,6 +540,8 @@ LLSettingsSky::validation_list_t LLSettingsSky::validationList()
         validation.push_back(Validator(SETTING_CLOUD_SHADOW,        true,  LLSD::TypeReal,  
             boost::bind(&Validator::verifyFloatRange, _1, LLSD(LLSDArray(0.0f)(1.0f)))));
         validation.push_back(Validator(SETTING_CLOUD_TEXTUREID,     false, LLSD::TypeUUID));
+        validation.push_back(Validator(SETTING_CLOUD_VARIANCE,      false,  LLSD::TypeReal,  
+            boost::bind(&Validator::verifyFloatRange, _1, LLSD(LLSDArray(0.0f)(1.0f)))));
 
         validation.push_back(Validator(SETTING_DOME_OFFSET,         false, LLSD::TypeReal,  
             boost::bind(&Validator::verifyFloatRange, _1, LLSD(LLSDArray(0.0f)(1.0f)))));
@@ -683,7 +686,8 @@ LLSD LLSettingsSky::defaults(const LLSettingsBase::TrackPosition& position)
         dfltsetting[SETTING_CLOUD_SCALE]        = LLSD::Real(0.4199);
         dfltsetting[SETTING_CLOUD_SCROLL_RATE]  = LLSDArray(0.0f)(0.0f);
         dfltsetting[SETTING_CLOUD_SHADOW]       = LLSD::Real(0.2699);
-    
+        dfltsetting[SETTING_CLOUD_VARIANCE]     = LLSD::Real(0.0);
+
         dfltsetting[SETTING_DOME_OFFSET]        = LLSD::Real(0.96f);
         dfltsetting[SETTING_DOME_RADIUS]        = LLSD::Real(15000.f);
         dfltsetting[SETTING_GAMMA]              = LLSD::Real(1.0);
@@ -1431,6 +1435,16 @@ void LLSettingsSky::setCloudShadow(F32 val)
     setValue(SETTING_CLOUD_SHADOW, val);
 }
 
+F32 LLSettingsSky::getCloudVariance() const
+{
+    return mSettings[SETTING_CLOUD_VARIANCE].asReal();
+}
+
+void LLSettingsSky::setCloudVariance(F32 val)
+{
+    setValue(SETTING_CLOUD_VARIANCE, val);
+}
+
 F32 LLSettingsSky::getDomeOffset() const
 {
     //return mSettings[SETTING_DOME_OFFSET].asReal();
diff --git a/indra/llinventory/llsettingssky.h b/indra/llinventory/llsettingssky.h
index 89dd6d20fd..796120ba03 100644
--- a/indra/llinventory/llsettingssky.h
+++ b/indra/llinventory/llsettingssky.h
@@ -57,6 +57,8 @@ public:
     static const std::string SETTING_CLOUD_SCROLL_RATE;
     static const std::string SETTING_CLOUD_SHADOW;
     static const std::string SETTING_CLOUD_TEXTUREID;
+    static const std::string SETTING_CLOUD_VARIANCE;
+
     static const std::string SETTING_DOME_OFFSET;
     static const std::string SETTING_DOME_RADIUS;
     static const std::string SETTING_GAMMA;
@@ -184,6 +186,9 @@ public:
     F32 getCloudShadow() const;
     void setCloudShadow(F32 val);
     
+    F32 getCloudVariance() const;
+    void setCloudVariance(F32 val);
+
     F32 getDomeOffset() const;
     F32 getDomeRadius() const;
 
diff --git a/indra/llrender/llshadermgr.cpp b/indra/llrender/llshadermgr.cpp
index 3927632dbe..e483f723f0 100644
--- a/indra/llrender/llshadermgr.cpp
+++ b/indra/llrender/llshadermgr.cpp
@@ -1327,6 +1327,7 @@ void LLShaderMgr::initAttribsAndUniforms()
     mReservedUniforms.push_back("halo_map");
     mReservedUniforms.push_back("moon_brightness");
     mReservedUniforms.push_back("moon_phase");
+    mReservedUniforms.push_back("cloud_variance");
 
 	llassert(mReservedUniforms.size() == END_RESERVED_UNIFORMS);
 
diff --git a/indra/llrender/llshadermgr.h b/indra/llrender/llshadermgr.h
index 489caa49ae..af34c70c54 100644
--- a/indra/llrender/llshadermgr.h
+++ b/indra/llrender/llshadermgr.h
@@ -243,6 +243,8 @@ public:
         MOON_BRIGHTNESS,
         MOON_PHASE,
 
+        CLOUD_VARIANCE,
+
 		END_RESERVED_UNIFORMS
 	} eGLSLReservedUniforms;
 
diff --git a/indra/newview/app_settings/shaders/class1/deferred/cloudsF.glsl b/indra/newview/app_settings/shaders/class1/deferred/cloudsF.glsl
index c1a9a6f454..caedd25221 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/cloudsF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/cloudsF.glsl
@@ -44,6 +44,8 @@ uniform float blend_factor;
 uniform vec4 cloud_pos_density1;
 uniform vec4 cloud_pos_density2;
 uniform vec4 gamma;
+uniform float cloud_scale;
+uniform float cloud_variance;
 
 VARYING vec2 vary_texcoord0;
 VARYING vec2 vary_texcoord1;
@@ -73,16 +75,19 @@ void main()
 	vec2 uv3 = vary_texcoord2.xy;
 	vec2 uv4 = vary_texcoord3.xy;
 
+    vec2 disturbance = vec2(cloudNoise(uv1 / 16.0f).x, cloudNoise((uv3 + uv1) / 16.0f).x) * cloud_variance * (1.0f - cloud_scale * 0.25f);
+
 	// Offset texture coords
-	uv1 += cloud_pos_density1.xy;	//large texture, visible density
+	uv1 += cloud_pos_density1.xy + disturbance;	//large texture, visible density
 	uv2 += cloud_pos_density1.xy;	//large texture, self shadow
-	uv3 += cloud_pos_density2.xy;	//small texture, visible density
+	uv3 += cloud_pos_density2.xy + disturbance;	//small texture, visible density
 	uv4 += cloud_pos_density2.xy;	//small texture, self shadow
 
 
 	// Compute alpha1, the main cloud opacity
+
 	float alpha1 = (cloudNoise(uv1).x - 0.5) + (cloudNoise(uv3).x - 0.5) * cloud_pos_density2.z;
-	alpha1 = min(max(alpha1 + cloudDensity, 0.) * 10. * cloud_pos_density1.z, 1.);
+	alpha1 = min(max(alpha1 + cloudDensity, 0.) * (10. + disturbance.y) * cloud_pos_density1.z, 1.);
 
 	// And smooth
 	alpha1 = 1. - alpha1 * alpha1;
@@ -96,7 +101,7 @@ void main()
 	// Compute alpha2, for self shadowing effect
 	// (1 - alpha2) will later be used as percentage of incoming sunlight
 	float alpha2 = (cloudNoise(uv2).x - 0.5);
-	alpha2 = min(max(alpha2 + cloudDensity, 0.) * 2.5 * cloud_pos_density1.z, 1.);
+	alpha2 = min(max(alpha2 + cloudDensity, 0.) * (2.5 + disturbance.x) * cloud_pos_density1.z, 1.);
 
 	// And smooth
 	alpha2 = 1. - alpha2;
diff --git a/indra/newview/app_settings/shaders/class2/windlight/cloudsF.glsl b/indra/newview/app_settings/shaders/class2/windlight/cloudsF.glsl
index 24fdb45749..cdd84faba9 100644
--- a/indra/newview/app_settings/shaders/class2/windlight/cloudsF.glsl
+++ b/indra/newview/app_settings/shaders/class2/windlight/cloudsF.glsl
@@ -36,10 +36,6 @@ out vec4 frag_color;
 VARYING vec4 vary_CloudColorSun;
 VARYING vec4 vary_CloudColorAmbient;
 VARYING float vary_CloudDensity;
-VARYING vec2 vary_texcoord0;
-VARYING vec2 vary_texcoord1;
-VARYING vec2 vary_texcoord2;
-VARYING vec2 vary_texcoord3;
 
 uniform sampler2D cloud_noise_texture;
 uniform sampler2D cloud_noise_texture_next;
@@ -47,16 +43,23 @@ uniform float blend_factor;
 uniform vec4 cloud_pos_density1;
 uniform vec4 cloud_pos_density2;
 uniform vec4 gamma;
+uniform float cloud_scale;
+uniform float cloud_variance;
+
+VARYING vec2 vary_texcoord0;
+VARYING vec2 vary_texcoord1;
+VARYING vec2 vary_texcoord2;
+VARYING vec2 vary_texcoord3;
 
 /// Soft clips the light with a gamma correction
 vec3 scaleSoftClip(vec3 light);
 
 vec4 cloudNoise(vec2 uv)
 {
-    vec4 a = texture2D(cloud_noise_texture, uv);
-    vec4 b = texture2D(cloud_noise_texture_next, uv);
-    vec4 samp = mix(a, b, blend_factor);
-	return samp;
+   vec4 a = texture2D(cloud_noise_texture, uv);
+   vec4 b = texture2D(cloud_noise_texture_next, uv);
+   vec4 cloud_noise_sample = mix(a, b, blend_factor);
+   return cloud_noise_sample;
 }
 
 void main()
@@ -71,26 +74,28 @@ void main()
 	vec2 uv3 = vary_texcoord2.xy;
 	vec2 uv4 = vary_texcoord3.xy;
 
+    vec2 disturbance = vec2(cloudNoise(uv1 / 16.0f).x, cloudNoise((uv3 + uv1) / 16.0f).x) * cloud_variance * (1.0f - cloud_scale * 0.25f);
+
 	// Offset texture coords
-	uv1 += cloud_pos_density1.xy;	//large texture, visible density
+	uv1 += cloud_pos_density1.xy + disturbance;	//large texture, visible density
 	uv2 += cloud_pos_density1.xy;	//large texture, self shadow
-	uv3 += cloud_pos_density2.xy;	//small texture, visible density
+	uv3 += cloud_pos_density2.xy + disturbance;	//small texture, visible density
 	uv4 += cloud_pos_density2.xy;	//small texture, self shadow
 
 
 	// Compute alpha1, the main cloud opacity
+
 	float alpha1 = (cloudNoise(uv1).x - 0.5) + (cloudNoise(uv3).x - 0.5) * cloud_pos_density2.z;
-	alpha1 = min(max(alpha1 + cloudDensity, 0.) * 10. * cloud_pos_density1.z, 1.);
+	alpha1 = min(max(alpha1 + cloudDensity, 0.) * (10. + disturbance.y) * cloud_pos_density1.z, 1.);
 
 	// And smooth
 	alpha1 = 1. - alpha1 * alpha1;
 	alpha1 = 1. - alpha1 * alpha1;	
 
-
 	// Compute alpha2, for self shadowing effect
 	// (1 - alpha2) will later be used as percentage of incoming sunlight
 	float alpha2 = (cloudNoise(uv2).x - 0.5);
-	alpha2 = min(max(alpha2 + cloudDensity, 0.) * 2.5 * cloud_pos_density1.z, 1.);
+	alpha2 = min(max(alpha2 + cloudDensity, 0.) * (2.5 + disturbance.x) * cloud_pos_density1.z, 1.);
 
 	// And smooth
 	alpha2 = 1. - alpha2;
diff --git a/indra/newview/app_settings/shaders/class3/deferred/cloudsF.glsl b/indra/newview/app_settings/shaders/class3/deferred/cloudsF.glsl
index d9fcc0a9ea..9f06319da3 100644
--- a/indra/newview/app_settings/shaders/class3/deferred/cloudsF.glsl
+++ b/indra/newview/app_settings/shaders/class3/deferred/cloudsF.glsl
@@ -36,10 +36,6 @@ out vec4 frag_color;
 VARYING vec4 vary_CloudColorSun;
 VARYING vec4 vary_CloudColorAmbient;
 VARYING float vary_CloudDensity;
-VARYING vec2 vary_texcoord0;
-VARYING vec2 vary_texcoord1;
-VARYING vec2 vary_texcoord2;
-VARYING vec2 vary_texcoord3;
 
 uniform sampler2D cloud_noise_texture;
 uniform sampler2D cloud_noise_texture_next;
@@ -47,19 +43,25 @@ uniform float blend_factor;
 uniform vec4 cloud_pos_density1;
 uniform vec4 cloud_pos_density2;
 uniform vec4 gamma;
+uniform float cloud_scale;
+uniform float cloud_variance;
 
-vec4 cloudNoise(vec2 uv)
-{
-	vec4 a = texture2D(cloud_noise_texture, uv);
-	vec4 b = texture2D(cloud_noise_texture_next, uv);
-    vec4 samp = mix(a, b, blend_factor);
-	return samp;
-}
-
+VARYING vec2 vary_texcoord0;
+VARYING vec2 vary_texcoord1;
+VARYING vec2 vary_texcoord2;
+VARYING vec2 vary_texcoord3;
 
 /// Soft clips the light with a gamma correction
 vec3 scaleSoftClip(vec3 light);
 
+vec4 cloudNoise(vec2 uv)
+{
+   vec4 a = texture2D(cloud_noise_texture, uv);
+   vec4 b = texture2D(cloud_noise_texture_next, uv);
+   vec4 cloud_noise_sample = mix(a, b, blend_factor);
+   return cloud_noise_sample;
+}
+
 void main()
 {
 	// Set variables
@@ -72,16 +74,19 @@ void main()
 	vec2 uv3 = vary_texcoord2.xy;
 	vec2 uv4 = vary_texcoord3.xy;
 
+    vec2 disturbance = vec2(cloudNoise(uv1 / 16.0f).x, cloudNoise((uv3 + uv1) / 16.0f).x) * cloud_variance * (1.0f - cloud_scale * 0.25f);
+
 	// Offset texture coords
-	uv1 += cloud_pos_density1.xy;	//large texture, visible density
+	uv1 += cloud_pos_density1.xy + disturbance;	//large texture, visible density
 	uv2 += cloud_pos_density1.xy;	//large texture, self shadow
-	uv3 += cloud_pos_density2.xy;	//small texture, visible density
+	uv3 += cloud_pos_density2.xy + disturbance;	//small texture, visible density
 	uv4 += cloud_pos_density2.xy;	//small texture, self shadow
 
 
 	// Compute alpha1, the main cloud opacity
+
 	float alpha1 = (cloudNoise(uv1).x - 0.5) + (cloudNoise(uv3).x - 0.5) * cloud_pos_density2.z;
-	alpha1 = min(max(alpha1 + cloudDensity, 0.) * 10. * cloud_pos_density1.z, 1.);
+	alpha1 = min(max(alpha1 + cloudDensity, 0.) * (10. + disturbance.y) * cloud_pos_density1.z, 1.);
 
 	// And smooth
 	alpha1 = 1. - alpha1 * alpha1;
@@ -91,7 +96,7 @@ void main()
 	// Compute alpha2, for self shadowing effect
 	// (1 - alpha2) will later be used as percentage of incoming sunlight
 	float alpha2 = (cloudNoise(uv2).x - 0.5);
-	alpha2 = min(max(alpha2 + cloudDensity, 0.) * 2.5 * cloud_pos_density1.z, 1.);
+	alpha2 = min(max(alpha2 + cloudDensity, 0.) * (2.5 + disturbance.x) * cloud_pos_density1.z, 1.);
 
 	// And smooth
 	alpha2 = 1. - alpha2;
diff --git a/indra/newview/lldrawpoolwlsky.cpp b/indra/newview/lldrawpoolwlsky.cpp
index b89588a463..b9e041a3d5 100644
--- a/indra/newview/lldrawpoolwlsky.cpp
+++ b/indra/newview/lldrawpoolwlsky.cpp
@@ -394,8 +394,13 @@ void LLDrawPoolWLSky::renderSkyClouds(const LLVector3& camPosLocal, F32 camHeigh
         cloud_shader->bindTexture(LLShaderMgr::CLOUD_NOISE_MAP, gSky.mVOSkyp->getCloudNoiseTex());
         cloud_shader->bindTexture(LLShaderMgr::CLOUD_NOISE_MAP_NEXT, gSky.mVOSkyp->getCloudNoiseTexNext());
 
-        F32 blend_factor = LLEnvironment::instance().getCurrentSky()->getBlendFactor();
+        LLSettingsSky::ptr_t psky = LLEnvironment::instance().getCurrentSky();
+
+        F32 blend_factor   = psky ? psky->getBlendFactor()   : 0.0f;
+        F32 cloud_variance = psky ? psky->getCloudVariance() : 0.0f;
+
         cloud_shader->uniform1f(LLShaderMgr::BLEND_FACTOR, blend_factor);
+        cloud_shader->uniform1f(LLShaderMgr::CLOUD_VARIANCE, cloud_variance);
 
 		/// Render the skydome
         renderDome(camPosLocal, camHeightLocal, cloud_shader);
diff --git a/indra/newview/llpaneleditsky.cpp b/indra/newview/llpaneleditsky.cpp
index 0d8c9a988a..d0e916363d 100644
--- a/indra/newview/llpaneleditsky.cpp
+++ b/indra/newview/llpaneleditsky.cpp
@@ -53,6 +53,8 @@ namespace
     const std::string   FIELD_SKY_CLOUD_COLOR("cloud_color");
     const std::string   FIELD_SKY_CLOUD_COVERAGE("cloud_coverage");
     const std::string   FIELD_SKY_CLOUD_SCALE("cloud_scale");
+    const std::string   FIELD_SKY_CLOUD_VARIANCE("cloud_variance");
+
     const std::string   FIELD_SKY_CLOUD_SCROLL_XY("cloud_scroll_xy");
     const std::string   FIELD_SKY_CLOUD_MAP("cloud_map");
     const std::string   FIELD_SKY_CLOUD_DENSITY_X("cloud_density_x");
@@ -254,6 +256,8 @@ BOOL LLPanelSettingsSkyCloudTab::postBuild()
     getChild<LLUICtrl>(FIELD_SKY_CLOUD_COLOR)->setCommitCallback([this](LLUICtrl *, const LLSD &) { onCloudColorChanged(); });
     getChild<LLUICtrl>(FIELD_SKY_CLOUD_COVERAGE)->setCommitCallback([this](LLUICtrl *, const LLSD &) { onCloudCoverageChanged(); });
     getChild<LLUICtrl>(FIELD_SKY_CLOUD_SCALE)->setCommitCallback([this](LLUICtrl *, const LLSD &) { onCloudScaleChanged(); });
+    getChild<LLUICtrl>(FIELD_SKY_CLOUD_VARIANCE)->setCommitCallback([this](LLUICtrl *, const LLSD &) { onCloudVarianceChanged(); });
+
     getChild<LLUICtrl>(FIELD_SKY_CLOUD_SCROLL_XY)->setCommitCallback([this](LLUICtrl *, const LLSD &) { onCloudScrollChanged(); });
     getChild<LLTextureCtrl>(FIELD_SKY_CLOUD_MAP)->setCommitCallback([this](LLUICtrl *, const LLSD &) { onCloudMapChanged(); });
     getChild<LLTextureCtrl>(FIELD_SKY_CLOUD_MAP)->setDefaultImageAssetID(LLSettingsSky::GetDefaultCloudNoiseTextureId());
@@ -278,6 +282,7 @@ void LLPanelSettingsSkyCloudTab::setEnabled(BOOL enabled)
     LLPanelSettingsSky::setEnabled(enabled);
     getChild<LLUICtrl>(FIELD_SKY_CLOUD_COVERAGE)->setEnabled(enabled);
     getChild<LLUICtrl>(FIELD_SKY_CLOUD_SCALE)->setEnabled(enabled);
+    getChild<LLUICtrl>(FIELD_SKY_CLOUD_VARIANCE)->setEnabled(enabled);
     getChild<LLUICtrl>(FIELD_SKY_CLOUD_DENSITY_X)->setEnabled(enabled);
     getChild<LLUICtrl>(FIELD_SKY_CLOUD_DENSITY_Y)->setEnabled(enabled);
     getChild<LLUICtrl>(FIELD_SKY_CLOUD_DENSITY_D)->setEnabled(enabled);
@@ -301,6 +306,7 @@ void LLPanelSettingsSkyCloudTab::refresh()
     getChild<LLColorSwatchCtrl>(FIELD_SKY_CLOUD_COLOR)->set(mSkySettings->getCloudColor());
     getChild<LLUICtrl>(FIELD_SKY_CLOUD_COVERAGE)->setValue(mSkySettings->getCloudShadow());
     getChild<LLUICtrl>(FIELD_SKY_CLOUD_SCALE)->setValue(mSkySettings->getCloudScale());
+    getChild<LLUICtrl>(FIELD_SKY_CLOUD_VARIANCE)->setValue(mSkySettings->getCloudVariance());
 
     LLVector2 cloudScroll(mSkySettings->getCloudScrollRate());
     getChild<LLUICtrl>(FIELD_SKY_CLOUD_SCROLL_XY)->setValue(cloudScroll.getValue());
@@ -339,6 +345,12 @@ void LLPanelSettingsSkyCloudTab::onCloudScaleChanged()
     setIsDirty();
 }
 
+void LLPanelSettingsSkyCloudTab::onCloudVarianceChanged()
+{
+    mSkySettings->setCloudVariance(getChild<LLUICtrl>(FIELD_SKY_CLOUD_VARIANCE)->getValue().asReal());
+    setIsDirty();
+}
+
 void LLPanelSettingsSkyCloudTab::onCloudScrollChanged()
 {
     LLVector2 scroll(getChild<LLUICtrl>(FIELD_SKY_CLOUD_SCROLL_XY)->getValue());
diff --git a/indra/newview/llpaneleditsky.h b/indra/newview/llpaneleditsky.h
index 829a65dae5..002586b550 100644
--- a/indra/newview/llpaneleditsky.h
+++ b/indra/newview/llpaneleditsky.h
@@ -95,6 +95,7 @@ private:
     void                    onCloudColorChanged();
     void                    onCloudCoverageChanged();
     void                    onCloudScaleChanged();
+    void                    onCloudVarianceChanged();
     void                    onCloudScrollChanged();
     void                    onCloudMapChanged();
     void                    onCloudDensityChanged();
diff --git a/indra/newview/llsettingsvo.cpp b/indra/newview/llsettingsvo.cpp
index 386a5deec6..17384a3a6b 100644
--- a/indra/newview/llsettingsvo.cpp
+++ b/indra/newview/llsettingsvo.cpp
@@ -657,10 +657,11 @@ LLSettingsSky::parammapping_t LLSettingsVOSky::getParameterMap() const
         param_map[SETTING_CLOUD_POS_DENSITY2] = LLShaderMgr::CLOUD_POS_DENSITY2;
         param_map[SETTING_CLOUD_SCALE] = LLShaderMgr::CLOUD_SCALE;
         param_map[SETTING_CLOUD_SHADOW] = LLShaderMgr::CLOUD_SHADOW;       
+        param_map[SETTING_CLOUD_VARIANCE] = LLShaderMgr::CLOUD_VARIANCE;
         param_map[SETTING_GLOW] = LLShaderMgr::GLOW;        
         param_map[SETTING_MAX_Y] = LLShaderMgr::MAX_Y;
         param_map[SETTING_SUNLIGHT_COLOR] = LLShaderMgr::SUNLIGHT_COLOR;
-
+        param_map[SETTING_MOON_BRIGHTNESS] = LLShaderMgr::MOON_BRIGHTNESS;
         param_map[SETTING_SKY_MOISTURE_LEVEL] = LLShaderMgr::MOISTURE_LEVEL;
         param_map[SETTING_SKY_DROPLET_RADIUS] = LLShaderMgr::DROPLET_RADIUS;
         param_map[SETTING_SKY_ICE_LEVEL] = LLShaderMgr::ICE_LEVEL;
diff --git a/indra/newview/skins/default/xui/en/panel_settings_sky_clouds.xml b/indra/newview/skins/default/xui/en/panel_settings_sky_clouds.xml
index 886e3c1e04..325df39f87 100644
--- a/indra/newview/skins/default/xui/en/panel_settings_sky_clouds.xml
+++ b/indra/newview/skins/default/xui/en/panel_settings_sky_clouds.xml
@@ -95,6 +95,29 @@
                     left_delta="-5"
                     top_delta="25"
                     width="200">
+                Cloud Variance:
+            </text>
+            <slider
+                    decimal_digits="2"
+                    follows="left|top"
+                    height="16"
+                    increment="0.01"
+                    initial_value="0"
+                    layout="topleft"
+                    left_delta="5"
+                    min_val="0"
+                    max_val="1.0"
+                    name="cloud_variance"
+                    top_delta="20"
+                    width="214"
+                    can_edit_text="true"/>
+            <text
+                    follows="left|top"
+                    height="10"
+                    layout="topleft"
+                    left_delta="-5"
+                    top_delta="25"
+                    width="200">
                 Cloud Scroll:
             </text>
             <xy_vector
@@ -244,4 +267,4 @@
                     can_edit_text="true"/>
         </layout_panel>
     </layout_stack>
-</panel>                
\ No newline at end of file
+</panel>