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diff --git a/indra/newview/app_settings/shaders/class2/windlight/atmosphericsFuncs.glsl b/indra/newview/app_settings/shaders/class2/windlight/atmosphericsFuncs.glsl
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+/**
+ * @file class2\windlight\atmosphericsFuncs.glsl
+ *
+ * $LicenseInfo:firstyear=2022&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2022, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+uniform vec3  lightnorm;
+uniform vec3  sunlight_color;
+uniform vec3 sunlight_linear;
+uniform vec3  moonlight_color;
+uniform vec3 moonlight_linear;
+uniform int   sun_up_factor;
+uniform vec3  ambient_color;
+uniform vec3 ambient_linear;
+uniform vec3  blue_horizon;
+uniform vec3 blue_horizon_linear;
+uniform vec3  blue_density;
+uniform vec3 blue_density_linear;
+uniform float haze_horizon;
+uniform float haze_density;
+uniform float haze_density_linear;
+uniform float cloud_shadow;
+uniform float density_multiplier;
+uniform float distance_multiplier;
+uniform float max_y;
+uniform vec3  glow;
+uniform float scene_light_strength;
+uniform mat3  ssao_effect_mat;
+uniform int   no_atmo;
+uniform float sun_moon_glow_factor;
+
+float getAmbientClamp() { return 1.0f; }
+
+vec3 srgb_to_linear(vec3 col);
+
+// return colors in sRGB space
+void calcAtmosphericVars(vec3 inPositionEye, vec3 light_dir, float ambFactor, out vec3 sunlit, out vec3 amblit, out vec3 additive,
+                         out vec3 atten, bool use_ao)
+{
+    vec3 rel_pos = inPositionEye;
+
+    //(TERRAIN) limit altitude
+    if (abs(rel_pos.y) > max_y) rel_pos *= (max_y / rel_pos.y);
+
+    vec3  rel_pos_norm = normalize(rel_pos);
+    float rel_pos_len  = length(rel_pos);
+    vec3  sunlight     = (sun_up_factor == 1) ? sunlight_color : moonlight_color;
+
+    // sunlight attenuation effect (hue and brightness) due to atmosphere
+    // this is used later for sunlight modulation at various altitudes
+    vec3 light_atten = (blue_density + vec3(haze_density * 0.25)) * (density_multiplier * max_y);
+    // I had thought blue_density and haze_density should have equal weighting,
+    // but attenuation due to haze_density tends to seem too strong
+
+    vec3 combined_haze = blue_density + vec3(haze_density);
+    vec3 blue_weight   = blue_density / combined_haze;
+    vec3 haze_weight   = vec3(haze_density) / combined_haze;
+
+    //(TERRAIN) compute sunlight from lightnorm y component. Factor is roughly cosecant(sun elevation) (for short rays like terrain)
+    float above_horizon_factor = 1.0 / max(1e-6, lightnorm.y);
+    sunlight *= exp(-light_atten * above_horizon_factor);  // for sun [horizon..overhead] this maps to an exp curve [0..1]
+
+    // main atmospheric scattering line integral
+    float density_dist = rel_pos_len * density_multiplier;
+
+    // Transparency (-> combined_haze)
+    // ATI Bugfix -- can't store combined_haze*density_dist*distance_multiplier in a variable because the ati
+    // compiler gets confused.
+    combined_haze = exp(-combined_haze * density_dist * distance_multiplier);
+
+    // final atmosphere attenuation factor
+    atten = combined_haze.rgb;
+
+    // compute haze glow
+    float haze_glow = dot(rel_pos_norm, lightnorm.xyz);
+
+    // dampen sun additive contrib when not facing it...
+    // SL-13539: This "if" clause causes an "additive" white artifact at roughly 77 degreees.
+    //    if (length(light_dir) > 0.01)
+    haze_glow *= max(0.0f, dot(light_dir, rel_pos_norm));
+
+    haze_glow = 1. - haze_glow;
+    // haze_glow is 0 at the sun and increases away from sun
+    haze_glow = max(haze_glow, .001);  // set a minimum "angle" (smaller glow.y allows tighter, brighter hotspot)
+    haze_glow *= glow.x;
+    // higher glow.x gives dimmer glow (because next step is 1 / "angle")
+    haze_glow = pow(haze_glow, glow.z);
+    // glow.z should be negative, so we're doing a sort of (1 / "angle") function
+
+    // add "minimum anti-solar illumination"
+    haze_glow += .25;
+
+    haze_glow *= sun_moon_glow_factor;
+
+    vec3 amb_color = ambient_color;
+
+    // increase ambient when there are more clouds
+    vec3 tmpAmbient = amb_color + (vec3(1.) - amb_color) * cloud_shadow * 0.5;
+
+    /*  decrease value and saturation (that in HSV, not HSL) for occluded areas
+     * // for HSV color/geometry used here, see http://gimp-savvy.com/BOOK/index.html?node52.html
+     * // The following line of code performs the equivalent of:
+     * float ambAlpha = tmpAmbient.a;
+     * float ambValue = dot(vec3(tmpAmbient), vec3(0.577)); // projection onto <1/rt(3), 1/rt(3), 1/rt(3)>, the neutral white-black axis
+     * vec3 ambHueSat = vec3(tmpAmbient) - vec3(ambValue);
+     * tmpAmbient = vec4(RenderSSAOEffect.valueFactor * vec3(ambValue) + RenderSSAOEffect.saturationFactor *(1.0 - ambFactor) * ambHueSat,
+     * ambAlpha);
+     */
+    if (use_ao)
+    {
+        tmpAmbient = mix(ssao_effect_mat * tmpAmbient.rgb, tmpAmbient.rgb, ambFactor);
+    }
+
+    // Similar/Shared Algorithms:
+    //     indra\llinventory\llsettingssky.cpp                                        -- LLSettingsSky::calculateLightSettings()
+    //     indra\newview\app_settings\shaders\class1\windlight\atmosphericsFuncs.glsl -- calcAtmosphericVars()
+    // haze color
+    vec3 cs = sunlight.rgb * (1. - cloud_shadow);
+    additive = (blue_horizon.rgb * blue_weight.rgb) * (cs + tmpAmbient.rgb) + (haze_horizon * haze_weight.rgb) * (cs * haze_glow + tmpAmbient.rgb);
+
+    // brightness of surface both sunlight and ambient
+    sunlit = sunlight.rgb;
+    amblit = tmpAmbient.rgb;
+    additive *= vec3(1.0 - combined_haze);
+}
+
+
+vec3 srgb_to_linear(vec3 col);
+
+// provide a touch of lighting in the opposite direction of the sun light 
+    // so areas in shadow don't lose all detail
+float ambientLighting(vec3 norm, vec3 light_dir)
+{
+    float ambient = min(abs(dot(norm.xyz, light_dir.xyz)), 1.0);
+    ambient *= 0.56;
+    ambient *= ambient;
+    ambient = (1.0 - ambient);
+    return ambient;
+}
+
+
+// return colors in linear space
+void calcAtmosphericVarsLinear(vec3 inPositionEye, vec3 norm, vec3 light_dir, out vec3 sunlit, out vec3 amblit, out vec3 additive,
+                         out vec3 atten)
+{
+#if 1
+    calcAtmosphericVars(inPositionEye, light_dir, 1.0, sunlit, amblit, additive, atten, false);
+    sunlit = srgb_to_linear(sunlit);
+    additive = srgb_to_linear(additive);
+    amblit = ambient_linear;
+
+    amblit *= ambientLighting(norm, light_dir);
+#else 
+
+    //EXPERIMENTAL -- attempt to factor out srgb_to_linear conversions above
+    vec3 rel_pos = inPositionEye;
+
+    //(TERRAIN) limit altitude
+    if (abs(rel_pos.y) > max_y) rel_pos *= (max_y / rel_pos.y);
+
+    vec3  rel_pos_norm = normalize(rel_pos);
+    float rel_pos_len  = length(rel_pos);
+    vec3  sunlight     = (sun_up_factor == 1) ? vec3(sunlight_linear, 0.0) : vec3(moonlight_linear, 0.0);
+
+    // sunlight attenuation effect (hue and brightness) due to atmosphere
+    // this is used later for sunlight modulation at various altitudes
+    vec3 light_atten = (blue_density + vec3(haze_density * 0.25)) * (density_multiplier * max_y);
+    // I had thought blue_density and haze_density should have equal weighting,
+    // but attenuation due to haze_density tends to seem too strong
+
+    vec3 combined_haze = blue_density + vec3(haze_density);
+    vec3 blue_weight   = blue_density / combined_haze;
+    vec3 haze_weight   = vec3(haze_density) / combined_haze;
+
+    //(TERRAIN) compute sunlight from lightnorm y component. Factor is roughly cosecant(sun elevation) (for short rays like terrain)
+    float above_horizon_factor = 1.0 / max(1e-6, lightnorm.y);
+    sunlight *= exp(-light_atten * above_horizon_factor);  // for sun [horizon..overhead] this maps to an exp curve [0..1]
+
+    // main atmospheric scattering line integral
+    float density_dist = rel_pos_len * density_multiplier;
+
+    // Transparency (-> combined_haze)
+    // ATI Bugfix -- can't store combined_haze*density_dist*distance_multiplier in a variable because the ati
+    // compiler gets confused.
+    combined_haze = exp(-combined_haze * density_dist * distance_multiplier);
+
+    // final atmosphere attenuation factor
+    atten = combined_haze.rgb;
+
+    // compute haze glow
+    float haze_glow = dot(rel_pos_norm, lightnorm.xyz);
+
+    // dampen sun additive contrib when not facing it...
+    // SL-13539: This "if" clause causes an "additive" white artifact at roughly 77 degreees.
+    //    if (length(light_dir) > 0.01)
+    haze_glow *= max(0.0f, dot(light_dir, rel_pos_norm));
+
+    haze_glow = 1. - haze_glow;
+    // haze_glow is 0 at the sun and increases away from sun
+    haze_glow = max(haze_glow, .001);  // set a minimum "angle" (smaller glow.y allows tighter, brighter hotspot)
+    haze_glow *= glow.x;
+    // higher glow.x gives dimmer glow (because next step is 1 / "angle")
+    haze_glow = pow(haze_glow, glow.z);
+    // glow.z should be negative, so we're doing a sort of (1 / "angle") function
+
+    // add "minimum anti-solar illumination"
+    haze_glow += .25;
+
+    haze_glow *= sun_moon_glow_factor;
+
+    //vec3 amb_color = vec4(ambient_linear, 0.0);
+    vec3 amb_color = ambient_color;
+
+    // increase ambient when there are more clouds
+    vec3 tmpAmbient = amb_color + (vec3(1.) - amb_color) * cloud_shadow * 0.5;
+
+    // Similar/Shared Algorithms:
+    //     indra\llinventory\llsettingssky.cpp                                        -- LLSettingsSky::calculateLightSettings()
+    //     indra\newview\app_settings\shaders\class1\windlight\atmosphericsFuncs.glsl -- calcAtmosphericVars()
+    // haze color
+    vec3 cs = sunlight.rgb * (1. - cloud_shadow);
+    additive = (blue_horizon.rgb * blue_weight.rgb) * (cs + tmpAmbient.rgb) + (haze_horizon * haze_weight.rgb) * (cs * haze_glow + tmpAmbient.rgb);
+
+    // brightness of surface both sunlight and ambient
+    sunlit = min(sunlight.rgb, vec3(1));
+    amblit = tmpAmbient.rgb;
+    additive *= vec3(1.0 - combined_haze);
+
+    //sunlit = sunlight_linear;
+    amblit = ambient_linear*0.8;
+#endif
+}