SL-18239 Unify PBR and non-PBR treatment of ambient/SSAO/irradiance. Restore SSAO to release version.

9 files changed, 73 insertions, 447 deletions

diff --git a/indra/newview/app_settings/shaders/class1/deferred/aoUtil.glsl b/indra/newview/app_settings/shaders/class1/deferred/aoUtil.glsl
index 73c125bbdc..23adbded5e 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/aoUtil.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/aoUtil.glsl
@@ -29,6 +29,8 @@ uniform sampler2DRect   depthMap;
 
 uniform float ssao_radius;
 uniform float ssao_max_radius;
+uniform float ssao_factor;
+uniform float ssao_factor_inv;
 
 uniform mat4 inv_proj;
 uniform vec2 screen_res;
@@ -81,14 +83,14 @@ float calcAmbientOcclusion(vec4 pos, vec3 norm, vec2 pos_screen)
 {
     float ret = 1.0;
     vec3 pos_world = pos.xyz;
-    
+    vec2 noise_reflect = texture2D(noiseMap, pos_screen.xy/128.0).xy;
         
     float angle_hidden = 0.0;
     float points = 0;
         
-    // it was found that keeping # of samples a constant was the fastest, probably due to compiler optimizations (unrolling?)
     float scale = min(ssao_radius / -pos_world.z, ssao_max_radius);
-    vec2 noise_reflect = texture2D(noiseMap, pos_screen.xy/128.0).xy;
+    
+    // it was found that keeping # of samples a constant was the fastest, probably due to compiler optimizations (unrolling?)
     for (int i = 0; i < 8; i++)
     {
         vec2 samppos_screen = pos_screen + scale * reflect(getKern(i), noise_reflect);
@@ -103,14 +105,14 @@ float calcAmbientOcclusion(vec4 pos, vec3 norm, vec2 pos_screen)
         //(k should vary inversely with # of samples, but this is taken care of later)
         
         float funky_val = (dot((samppos_world - 0.05*norm - pos_world), norm) > 0.0) ? 1.0 : 0.0;
-        angle_hidden = angle_hidden + funky_val * min(1.0/dist2, 1.0);
+        angle_hidden = angle_hidden + funky_val * min(1.0/dist2, ssao_factor_inv);
             
         // 'blocked' samples (significantly closer to camera relative to pos_world) are "no data", not "no occlusion" 
         float diffz_val = (diff.z > -1.0) ? 1.0 : 0.0;
         points = points + diffz_val;
     }
-
-    angle_hidden = min(angle_hidden/points, 1.0);
+        
+    angle_hidden = min(ssao_factor*angle_hidden/points, 1.0);
     
     float points_val = (points > 0.0) ? 1.0 : 0.0;
     ret = (1.0 - (points_val * angle_hidden));
diff --git a/indra/newview/app_settings/shaders/class1/deferred/materialF.glsl b/indra/newview/app_settings/shaders/class1/deferred/materialF.glsl
index 44bf61be84..beadec434c 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/materialF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/materialF.glsl
@@ -27,395 +27,26 @@
 
 //class1/deferred/materialF.glsl
 
-// This shader is used for both writing opaque/masked content to the gbuffer and writing blended content to the framebuffer during the alpha pass.
+// Debug stub for non-pbr material
 
-#define DIFFUSE_ALPHA_MODE_NONE     0
 #define DIFFUSE_ALPHA_MODE_BLEND    1
-#define DIFFUSE_ALPHA_MODE_MASK     2
-#define DIFFUSE_ALPHA_MODE_EMISSIVE 3
-
-uniform float emissive_brightness;  // fullbright flag, 1.0 == fullbright, 0.0 otherwise
-uniform int sun_up_factor;
-
-#ifdef WATER_FOG
-vec4 applyWaterFogView(vec3 pos, vec4 color);
-#endif
-
-vec3 atmosFragLighting(vec3 l, vec3 additive, vec3 atten);
-vec3 scaleSoftClipFrag(vec3 l);
-
-vec3 fullbrightAtmosTransportFrag(vec3 light, vec3 additive, vec3 atten);
-vec3 fullbrightScaleSoftClip(vec3 light);
-
-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 srgb_to_linear(vec3 cs);
-vec3 linear_to_srgb(vec3 cs);
 
 #if (DIFFUSE_ALPHA_MODE == DIFFUSE_ALPHA_MODE_BLEND)
-
-#ifdef DEFINE_GL_FRAGCOLOR
 out vec4 frag_color;
 #else
-#define frag_color gl_FragColor
+out vec4 frag_data[4];
 #endif
 
-#ifdef HAS_SUN_SHADOW
-float sampleDirectionalShadow(vec3 pos, vec3 norm, vec2 pos_screen);
-#endif
-
-uniform samplerCube environmentMap;
-uniform sampler2D     lightFunc;
-
-// Inputs
-uniform vec4 morphFactor;
-uniform vec3 camPosLocal;
-uniform mat3 env_mat;
-
-uniform vec3 sun_dir;
-uniform vec3 moon_dir;
-VARYING vec2 vary_fragcoord;
-
-VARYING vec3 vary_position;
-
-uniform mat4 proj_mat;
-uniform mat4 inv_proj;
-uniform vec2 screen_res;
-
-uniform vec4 light_position[8];
-uniform vec3 light_direction[8];
-uniform vec4 light_attenuation[8];
-uniform vec3 light_diffuse[8];
-
-float getAmbientClamp();
-
-vec3 calcPointLightOrSpotLight(vec3 light_col, vec3 npos, vec3 diffuse, vec4 spec, vec3 v, vec3 n, vec4 lp, vec3 ln, float la, float fa, float is_pointlight, inout float glare, float ambiance)
-{
-    // SL-14895 inverted attenuation work-around
-    // This routine is tweaked to match deferred lighting, but previously used an inverted la value. To reconstruct
-    // that previous value now that the inversion is corrected, we reverse the calculations in LLPipeline::setupHWLights()
-    // to recover the `adjusted_radius` value previously being sent as la.
-    float falloff_factor = (12.0 * fa) - 9.0;
-    float inverted_la = falloff_factor / la;
-    // Yes, it makes me want to cry as well. DJH
-    
-    vec3 col = vec3(0);
-
-    //get light vector
-    vec3 lv = lp.xyz - v;
-
-    //get distance
-    float dist = length(lv);
-    float da = 1.0;
-
-    dist /= inverted_la;
-
-    if (dist > 0.0 && inverted_la > 0.0)
-    {
-        //normalize light vector
-        lv = normalize(lv);
-
-        //distance attenuation
-        float dist_atten = clamp(1.0 - (dist - 1.0*(1.0 - fa)) / fa, 0.0, 1.0);
-        dist_atten *= dist_atten;
-        dist_atten *= 2.0f;
-
-        if (dist_atten <= 0.0)
-        {
-            return col;
-        }
-
-        // spotlight coefficient.
-        float spot = max(dot(-ln, lv), is_pointlight);
-        da *= spot*spot; // GL_SPOT_EXPONENT=2
-
-        //angular attenuation
-        da *= dot(n, lv);
-
-        float lit = 0.0f;
-
-        float amb_da = ambiance;
-        if (da >= 0)
-        {
-            lit = max(da * dist_atten, 0.0);
-            col = lit * light_col * diffuse;
-            amb_da += (da*0.5 + 0.5) * ambiance;
-        }
-        amb_da += (da*da*0.5 + 0.5) * ambiance;
-        amb_da *= dist_atten;
-        amb_da = min(amb_da, 1.0f - lit);
-
-        // SL-10969 need to see why these are blown out
-        //col.rgb += amb_da * light_col * diffuse;
-
-        if (spec.a > 0.0)
-        {
-            //vec3 ref = dot(pos+lv, norm);
-            vec3 h = normalize(lv + npos);
-            float nh = dot(n, h);
-            float nv = dot(n, npos);
-            float vh = dot(npos, h);
-            float sa = nh;
-            float fres = pow(1 - dot(h, npos), 5)*0.4 + 0.5;
-
-            float gtdenom = 2 * nh;
-            float gt = max(0, min(gtdenom * nv / vh, gtdenom * da / vh));
-
-            if (nh > 0.0)
-            {
-                float scol = fres*texture2D(lightFunc, vec2(nh, spec.a)).r*gt / (nh*da);
-                vec3 speccol = lit*scol*light_col.rgb*spec.rgb;
-                speccol = clamp(speccol, vec3(0), vec3(1));
-                col += speccol;
-
-                float cur_glare = max(speccol.r, speccol.g);
-                cur_glare = max(cur_glare, speccol.b);
-                glare = max(glare, speccol.r);
-                glare += max(cur_glare, 0.0);
-            }
-        }
-    }
-
-    return max(col, vec3(0.0, 0.0, 0.0));
-}
-
-#else
-#ifdef DEFINE_GL_FRAGCOLOR
-out vec4 frag_data[3];
-#else
-#define frag_data gl_FragData
-#endif
-#endif
-
-uniform sampler2D diffuseMap;  //always in sRGB space
-
-#ifdef HAS_NORMAL_MAP
-uniform sampler2D bumpMap;
-#endif
-
-#ifdef HAS_SPECULAR_MAP
-uniform sampler2D specularMap;
-
-VARYING vec2 vary_texcoord2;
-#endif
-
-uniform float env_intensity;
-uniform vec4 specular_color;  // specular color RGB and specular exponent (glossiness) in alpha
-
-#if (DIFFUSE_ALPHA_MODE == DIFFUSE_ALPHA_MODE_MASK)
-uniform float minimum_alpha;
-#endif
-
-#ifdef HAS_NORMAL_MAP
-VARYING vec3 vary_mat0;
-VARYING vec3 vary_mat1;
-VARYING vec3 vary_mat2;
-VARYING vec2 vary_texcoord1;
-#else
-VARYING vec3 vary_normal;
-#endif
-
-VARYING vec4 vertex_color;
-VARYING vec2 vary_texcoord0;
-
-vec2 encode_normal(vec3 n);
-
 void main()
 {
-    vec2 pos_screen = vary_texcoord0.xy;
-
-    vec4 diffcol = texture2D(diffuseMap, vary_texcoord0.xy);
-	diffcol.rgb *= vertex_color.rgb;
-
-#if (DIFFUSE_ALPHA_MODE == DIFFUSE_ALPHA_MODE_MASK)
-
-    // Comparing floats cast from 8-bit values, produces acne right at the 8-bit transition points
-    float bias = 0.001953125; // 1/512, or half an 8-bit quantization
-    if (diffcol.a < minimum_alpha-bias)
-    {
-        discard;
-    }
-#endif
-
 #if (DIFFUSE_ALPHA_MODE == DIFFUSE_ALPHA_MODE_BLEND)
-	vec3 gamma_diff = diffcol.rgb;
-	diffcol.rgb = srgb_to_linear(diffcol.rgb);
-#endif
-
-#ifdef HAS_SPECULAR_MAP
-    vec4 spec = texture2D(specularMap, vary_texcoord2.xy);
-    spec.rgb *= specular_color.rgb;
-#else
-    vec4 spec = vec4(specular_color.rgb, 1.0);
-#endif
-
-#ifdef HAS_NORMAL_MAP
-	vec4 norm = texture2D(bumpMap, vary_texcoord1.xy);
-
-	norm.xyz = norm.xyz * 2 - 1;
-
-	vec3 tnorm = vec3(dot(norm.xyz,vary_mat0),
-			  dot(norm.xyz,vary_mat1),
-			  dot(norm.xyz,vary_mat2));
-#else
-	vec4 norm = vec4(0,0,0,1.0);
-	vec3 tnorm = vary_normal;
-#endif
-
-    norm.xyz = normalize(tnorm.xyz);
-
-    vec2 abnormal = encode_normal(norm.xyz);
-
-    vec4 final_color = diffcol;
-
-#if (DIFFUSE_ALPHA_MODE != DIFFUSE_ALPHA_MODE_EMISSIVE)
-	final_color.a = emissive_brightness;
-#else
-	final_color.a = max(final_color.a, emissive_brightness);
-#endif
-
-    vec4 final_specular = spec;
-    
-#ifdef HAS_SPECULAR_MAP
-    vec4 final_normal = vec4(encode_normal(normalize(tnorm)), env_intensity * spec.a, GBUFFER_FLAG_HAS_ATMOS);
-	final_specular.a = specular_color.a * norm.a;
+    frag_color = vec4(1,0,0,0.5);
 #else
-	vec4 final_normal = vec4(encode_normal(normalize(tnorm)), env_intensity, GBUFFER_FLAG_HAS_ATMOS);
-	final_specular.a = specular_color.a;
-#endif
-
-#if (DIFFUSE_ALPHA_MODE == DIFFUSE_ALPHA_MODE_BLEND)
-
-    //forward rendering, output just lit sRGBA
-    vec3 pos = vary_position;
-
-    float shadow = 1.0f;
-
-#ifdef HAS_SUN_SHADOW
-    shadow = sampleDirectionalShadow(pos.xyz, norm.xyz, pos_screen);
-#endif
-
-    spec = final_specular;
-    vec4 diffuse = final_color;
-    float envIntensity = final_normal.z;
-
-    vec3 color = vec3(0,0,0);
-
-    vec3 light_dir = (sun_up_factor == 1) ? sun_dir : moon_dir;
-
-    float bloom = 0.0;
-    vec3 sunlit;
-    vec3 amblit;
-    vec3 additive;
-    vec3 atten;
-
-    calcAtmosphericVars(pos.xyz, light_dir, 1.0, sunlit, amblit, additive, atten, false);
-    
-        // This call breaks the Mac GLSL compiler/linker for unknown reasons (17Mar2020)
-        // The call is either a no-op or a pure (pow) gamma adjustment, depending on GPU level
-        // TODO: determine if we want to re-apply the gamma adjustment, and if so understand & fix Mac breakage
-        //color = fullbrightScaleSoftClip(color);
-
-    vec3 refnormpersp = normalize(reflect(pos.xyz, norm.xyz));
-
-    //we're in sRGB space, so gamma correct this dot product so 
-    // lighting from the sun stays sharp
-    float da = clamp(dot(normalize(norm.xyz), light_dir.xyz), 0.0, 1.0);
-    da = pow(da, 1.0 / 1.3);
-
-    color = amblit;
-
-    //darken ambient for normals perpendicular to light vector so surfaces in shadow 
-    // and facing away from light still have some definition to them.
-    // do NOT gamma correct this dot product so ambient lighting stays soft
-    float ambient = min(abs(dot(norm.xyz, sun_dir.xyz)), 1.0);
-    ambient *= 0.5;
-    ambient *= ambient;
-    ambient = (1.0 - ambient);
-
-    vec3 sun_contrib = min(da, shadow) * sunlit;
-    
-    color *= ambient;
-
-    color += sun_contrib;
-
-    color *= gamma_diff.rgb;
-
-    float glare = 0.0;
-
-    if (spec.a > 0.0)  // specular reflection
-    {
-        float sa        = dot(refnormpersp, sun_dir.xyz);
-        vec3  dumbshiny = sunlit * shadow * (texture2D(lightFunc, vec2(sa, spec.a)).r);
-
-        // add the two types of shiny together
-        vec3 spec_contrib = dumbshiny * spec.rgb;
-        bloom             = dot(spec_contrib, spec_contrib) / 6;
-
-        glare = max(spec_contrib.r, spec_contrib.g);
-        glare = max(glare, spec_contrib.b);
-
-        color += spec_contrib;
-    }
-
-    color = mix(color.rgb, diffcol.rgb, diffuse.a);
-
-    if (envIntensity > 0.0)
-    {
-        //add environmentmap
-        vec3 env_vec = env_mat * refnormpersp;
-
-        vec3 reflected_color = textureCube(environmentMap, env_vec).rgb;
-
-        color = mix(color, reflected_color, envIntensity);
-
-        float cur_glare = max(reflected_color.r, reflected_color.g);
-        cur_glare = max(cur_glare, reflected_color.b);
-        cur_glare *= envIntensity*4.0;
-        glare += cur_glare;
-    }
-
-    color = atmosFragLighting(color, additive, atten);
-    color = scaleSoftClipFrag(color);
-
-    //convert to linear before adding local lights
-    color = srgb_to_linear(color);
-
-    vec3 npos = normalize(-pos.xyz);
-
-    vec3 light = vec3(0, 0, 0);
-    
-    final_specular.rgb = srgb_to_linear(final_specular.rgb); // SL-14035
-
-#define LIGHT_LOOP(i) light.rgb += calcPointLightOrSpotLight(light_diffuse[i].rgb, npos, diffuse.rgb, final_specular, pos.xyz, norm.xyz, light_position[i], light_direction[i].xyz, light_attenuation[i].x, light_attenuation[i].y, light_attenuation[i].z, glare, light_attenuation[i].w );
-
-    LIGHT_LOOP(1)
-        LIGHT_LOOP(2)
-        LIGHT_LOOP(3)
-        LIGHT_LOOP(4)
-        LIGHT_LOOP(5)
-        LIGHT_LOOP(6)
-        LIGHT_LOOP(7)
-
-    color += light;
-
-    glare = min(glare, 1.0);
-    float al = max(diffcol.a, glare)*vertex_color.a;
-
-#ifdef WATER_FOG
-    vec4 temp = applyWaterFogView(pos, vec4(color, al));
-    color = temp.rgb;
-    al = temp.a;
-#endif
-
-    frag_color = vec4(color, al);
-
-#else // mode is not DIFFUSE_ALPHA_MODE_BLEND, encode to gbuffer 
-
-    // deferred path               // See: C++: addDeferredAttachment(), shader: softenLightF.glsl
-    frag_data[0] = final_color;    // gbuffer is sRGB
-    frag_data[1] = final_specular; // XYZ = Specular color. W = Specular exponent.
-    frag_data[2] = final_normal;   // XY = Normal.  Z = Env. intensity. W = 1 skip atmos (mask off fog)
+    // emissive red PBR material
+    frag_data[0] = vec4(0,0,0,0);
+    frag_data[1] = vec4(0,0,0,0);
+    frag_data[2] = vec4(1,0,0,GBUFFER_FLAG_HAS_PBR);
+    frag_data[3] = vec4(1,0,0,0);
 #endif
 }
 
diff --git a/indra/newview/app_settings/shaders/class1/windlight/atmosphericsFuncs.glsl b/indra/newview/app_settings/shaders/class1/windlight/atmosphericsFuncs.glsl
index 28d1ae2027..12f500e224 100644
--- a/indra/newview/app_settings/shaders/class1/windlight/atmosphericsFuncs.glsl
+++ b/indra/newview/app_settings/shaders/class1/windlight/atmosphericsFuncs.glsl
@@ -37,8 +37,8 @@ void calcAtmosphericVars(vec3 inPositionEye, vec3 light_dir, float ambFactor, ou
     atten = vec3(1,0,1);
 }
 
-void calcAtmosphericVarsLinear(vec3 inPositionEye, vec3 light_dir, float ambFactor, out vec3 sunlit, out vec3 amblit, out vec3 additive,
-                         out vec3 atten, bool use_ao)
+void calcAtmosphericVarsLinear(vec3 inPositionEye, vec3 norm, vec3 light_dir, out vec3 sunlit, out vec3 amblit, out vec3 additive,
+                         out vec3 atten)
 {
     amblit = vec3(0.2, 0, 0.2);
     sunlit = vec3(1,0,1);
diff --git a/indra/newview/app_settings/shaders/class2/deferred/alphaF.glsl b/indra/newview/app_settings/shaders/class2/deferred/alphaF.glsl
index 39aec699fe..b4406aabc0 100644
--- a/indra/newview/app_settings/shaders/class2/deferred/alphaF.glsl
+++ b/indra/newview/app_settings/shaders/class2/deferred/alphaF.glsl
@@ -80,7 +80,7 @@ vec2 encode_normal (vec3 n);
 vec3 scaleSoftClipFragLinear(vec3 l);
 vec3 atmosFragLightingLinear(vec3 light, vec3 additive, vec3 atten);
 
-void calcAtmosphericVarsLinear(vec3 inPositionEye, vec3 light_dir, float ambFactor, out vec3 sunlit, out vec3 amblit, out vec3 atten, out vec3 additive, bool use_ao);
+void calcAtmosphericVarsLinear(vec3 inPositionEye, vec3 norm, vec3 light_dir, out vec3 sunlit, out vec3 amblit, out vec3 atten, out vec3 additive);
 
 #ifdef HAS_SHADOW
 float sampleDirectionalShadow(vec3 pos, vec3 norm, vec2 pos_screen);
@@ -243,12 +243,12 @@ void main()
     vec3 additive;
     vec3 atten;
 
-    calcAtmosphericVarsLinear(pos.xyz, light_dir, 1.0, sunlit, amblit, additive, atten, false);
+    calcAtmosphericVarsLinear(pos.xyz, norm, light_dir, sunlit, amblit, additive, atten);
 
-    vec3 ambenv;
+    vec3 irradiance;
     vec3 glossenv;
     vec3 legacyenv;
-    sampleReflectionProbesLegacy(ambenv, glossenv, legacyenv, pos.xyz, norm.xyz, 0.0, 0.0);
+    sampleReflectionProbesLegacy(irradiance, glossenv, legacyenv, pos.xyz, norm.xyz, 0.0, 0.0);
     
 
     float da = dot(norm.xyz, light_dir.xyz);
@@ -261,15 +261,9 @@ void main()
 
     color.a   = final_alpha;
 
-    float ambient = min(abs(dot(norm.xyz, sun_dir.xyz)), 1.0);
-    ambient *= 0.5;
-    ambient *= ambient;
-    ambient = (1.0 - ambient);
-
     vec3 sun_contrib = min(final_da, shadow) * sunlit;
 
-    color.rgb = max(amblit, ambenv);
-    color.rgb *= ambient;
+    color.rgb = max(amblit, irradiance);
 
     color.rgb += sun_contrib;
 
diff --git a/indra/newview/app_settings/shaders/class2/deferred/pbralphaF.glsl b/indra/newview/app_settings/shaders/class2/deferred/pbralphaF.glsl
index 13544af0b1..9bbc4f87bf 100644
--- a/indra/newview/app_settings/shaders/class2/deferred/pbralphaF.glsl
+++ b/indra/newview/app_settings/shaders/class2/deferred/pbralphaF.glsl
@@ -74,8 +74,7 @@ uniform vec2 light_deferred_attenuation[8]; // light size and falloff
 vec3 srgb_to_linear(vec3 c);
 vec3 linear_to_srgb(vec3 c);
 
-// These are in deferredUtil.glsl but we can't set: mFeatures.isDeferred to include it
-void calcAtmosphericVarsLinear(vec3 inPositionEye, vec3 light_dir, float ambFactor, out vec3 sunlit, out vec3 amblit, out vec3 additive, out vec3 atten, bool use_ao);
+void calcAtmosphericVarsLinear(vec3 inPositionEye, vec3 norm, vec3 light_dir, out vec3 sunlit, out vec3 amblit, out vec3 atten, out vec3 additive);
 vec3 atmosFragLightingLinear(vec3 light, vec3 additive, vec3 atten);
 vec3 scaleSoftClipFragLinear(vec3 l);
 
@@ -140,15 +139,6 @@ void main()
     vec3  light_dir   = (sun_up_factor == 1) ? sun_dir : moon_dir;
     vec3  pos         = vary_position;
 
-    float scol = 1.0;
-    float ambocc = 1.0;
-
-    vec3 sunlit;
-    vec3 amblit;
-    vec3 additive;
-    vec3 atten;
-    calcAtmosphericVarsLinear(pos.xyz, light_dir, ambocc, sunlit, amblit, additive, atten, true);
-
 
 // IF .mFeatures.mIndexedTextureChannels = LLGLSLShader::sIndexedTextureChannels;
 //    vec3 col = vertex_color.rgb * diffuseLookup(vary_texcoord0.xy).rgb;
@@ -174,6 +164,13 @@ void main()
 
     norm *= gl_FrontFacing ? 1.0 : -1.0;
 
+    float scol = 1.0;
+    vec3 sunlit;
+    vec3 amblit;
+    vec3 additive;
+    vec3 atten;
+    calcAtmosphericVarsLinear(pos.xyz, norm, light_dir, sunlit, amblit, additive, atten);
+
 #ifdef HAS_SHADOW
     vec2 frag = vary_fragcoord.xy/vary_fragcoord.z*0.5+0.5;
     frag *= screen_res;
diff --git a/indra/newview/app_settings/shaders/class2/windlight/atmosphericsFuncs.glsl b/indra/newview/app_settings/shaders/class2/windlight/atmosphericsFuncs.glsl
index 0093e8a31e..8937488484 100644
--- a/indra/newview/app_settings/shaders/class2/windlight/atmosphericsFuncs.glsl
+++ b/indra/newview/app_settings/shaders/class2/windlight/atmosphericsFuncs.glsl
@@ -146,15 +146,29 @@ void calcAtmosphericVars(vec3 inPositionEye, vec3 light_dir, float ambFactor, ou
 
 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 light_dir, float ambFactor, out vec3 sunlit, out vec3 amblit, out vec3 additive,
-                         out vec3 atten, bool use_ao)
+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
diff --git a/indra/newview/app_settings/shaders/class3/deferred/materialF.glsl b/indra/newview/app_settings/shaders/class3/deferred/materialF.glsl
index c1f60da7ee..1150d40007 100644
--- a/indra/newview/app_settings/shaders/class3/deferred/materialF.glsl
+++ b/indra/newview/app_settings/shaders/class3/deferred/materialF.glsl
@@ -43,7 +43,7 @@ vec4 applyWaterFogView(vec3 pos, vec4 color);
 
 vec3 atmosFragLightingLinear(vec3 l, vec3 additive, vec3 atten);
 vec3 scaleSoftClipFragLinear(vec3 l);
-void calcAtmosphericVarsLinear(vec3 inPositionEye, vec3 light_dir, float ambFactor, out vec3 sunlit, out vec3 amblit, out vec3 additive, out vec3 atten, bool use_ao);
+void calcAtmosphericVarsLinear(vec3 inPositionEye, vec3 norm, vec3 light_dir, out vec3 sunlit, out vec3 amblit, out vec3 atten, out vec3 additive);
 vec3 fullbrightAtmosTransportFragLinear(vec3 light, vec3 additive, vec3 atten);
 
 vec3 srgb_to_linear(vec3 cs);
@@ -301,7 +301,7 @@ void main()
     vec3 amblit;
     vec3 additive;
     vec3 atten;
-    calcAtmosphericVarsLinear(pos.xyz, light_dir, 1.0, sunlit, amblit, additive, atten, false);
+    calcAtmosphericVarsLinear(pos.xyz, norm.xyz, light_dir, sunlit, amblit, additive, atten);
     
     vec3 ambenv;
     vec3 glossenv;
@@ -311,12 +311,6 @@ void main()
     // use sky settings ambient or irradiance map sample, whichever is brighter
     color = max(amblit, ambenv);
 
-    float ambient = min(abs(dot(norm.xyz, light_dir.xyz)), 1.0);
-    ambient *= 0.5;
-    ambient *= ambient;
-    ambient = (1.0 - ambient);
-    color.rgb *= ambient;
-
     float da          = clamp(dot(norm.xyz, light_dir.xyz), 0.0, 1.0);
     vec3 sun_contrib = min(da, shadow) * sunlit;
     color.rgb += sun_contrib;
diff --git a/indra/newview/app_settings/shaders/class3/deferred/reflectionProbeF.glsl b/indra/newview/app_settings/shaders/class3/deferred/reflectionProbeF.glsl
index a1125cc1dd..80f9e29123 100644
--- a/indra/newview/app_settings/shaders/class3/deferred/reflectionProbeF.glsl
+++ b/indra/newview/app_settings/shaders/class3/deferred/reflectionProbeF.glsl
@@ -529,7 +529,6 @@ void sampleReflectionProbesLegacy(inout vec3 ambenv, inout vec3 glossenv, inout
     vec3 refnormpersp = reflect(pos.xyz, norm.xyz);
 
     ambenv = sampleProbeAmbient(pos, norm);
-    ambenv /= 1.725;
 
     if (glossiness > 0.0)
     {
diff --git a/indra/newview/app_settings/shaders/class3/deferred/softenLightF.glsl b/indra/newview/app_settings/shaders/class3/deferred/softenLightF.glsl
index 3e44e87f1e..e5ffe55163 100644
--- a/indra/newview/app_settings/shaders/class3/deferred/softenLightF.glsl
+++ b/indra/newview/app_settings/shaders/class3/deferred/softenLightF.glsl
@@ -69,7 +69,7 @@ uniform vec2 screen_res;
 vec3 getNorm(vec2 pos_screen);
 vec4 getPositionWithDepth(vec2 pos_screen, float depth);
 
-void calcAtmosphericVarsLinear(vec3 inPositionEye, vec3 light_dir, float ambFactor, out vec3 sunlit, out vec3 amblit, out vec3 additive, out vec3 atten, bool use_ao);
+void calcAtmosphericVarsLinear(vec3 inPositionEye, vec3 norm, vec3 light_dir, out vec3 sunlit, out vec3 amblit, out vec3 atten, out vec3 additive);
 vec3  atmosFragLightingLinear(vec3 l, vec3 additive, vec3 atten);
 vec3  scaleSoftClipFragLinear(vec3 l);
 vec3  fullbrightAtmosTransportFragLinear(vec3 light, vec3 additive, vec3 atten);
@@ -112,9 +112,11 @@ void main()
     float depth        = texture2DRect(depthMap, tc.xy).r;
     vec4  pos          = getPositionWithDepth(tc, depth);
     vec4  norm         = texture2DRect(normalMap, tc);
+    float envIntensity = norm.z;
+    norm.xyz           = getNorm(tc);
     vec3  light_dir   = (sun_up_factor == 1) ? sun_dir : moon_dir;
 
-    vec4 diffuse     = texture2DRect(diffuseRect, tc);
+    vec4 baseColor     = texture2DRect(diffuseRect, tc);
     vec4 spec        = texture2DRect(specularRect, vary_fragcoord.xy); // NOTE: PBR linear Emissive
 
 #if defined(HAS_SUN_SHADOW) || defined(HAS_SSAO)
@@ -122,7 +124,7 @@ void main()
 #endif
 
 #if defined(HAS_SUN_SHADOW)
-    float scol       = max(scol_ambocc.r, diffuse.a);
+    float scol       = max(scol_ambocc.r, baseColor.a);
 #else
     float scol = 1.0;
 #endif
@@ -140,15 +142,10 @@ void main()
     vec3 additive;
     vec3 atten;
 
-    calcAtmosphericVarsLinear(pos.xyz, light_dir, 1.0, sunlit, amblit, additive, atten, false);
-
-    vec3 ambenv;
-    vec3 glossenv;
-    vec3 legacyenv;
+    calcAtmosphericVarsLinear(pos.xyz, norm.xyz, light_dir, sunlit, amblit, additive, atten);
 
     if (GET_GBUFFER_FLAG(GBUFFER_FLAG_HAS_PBR))
     {
-        norm.xyz           = getNorm(tc);
         vec3 orm = texture2DRect(specularRect, tc).rgb; 
         float perceptualRoughness = orm.g;
         float metallic = orm.b;
@@ -162,11 +159,11 @@ void main()
         vec3  radiance  = vec3(0);
         sampleReflectionProbes(irradiance, radiance, pos.xyz, norm.xyz, gloss);
         
-        irradiance       = max(amblit*0.75,irradiance);
+        // Take maximium of legacy ambient vs irradiance sample as irradiance
+        // NOTE: ao is applied in pbrIbl, do not apply here
+        irradiance       = max(amblit,irradiance);
 
         vec3 f0 = vec3(0.04);
-        vec3 baseColor = diffuse.rgb;
-
         vec3 diffuseColor = baseColor.rgb*(vec3(1.0)-f0);
         diffuseColor *= 1.0 - metallic;
 
@@ -185,35 +182,33 @@ void main()
     }
     else if (!GET_GBUFFER_FLAG(GBUFFER_FLAG_HAS_ATMOS))
     {
-        //should only be true of WL sky, just port over diffuse value
-        color = srgb_to_linear(diffuse.rgb);
+        //should only be true of WL sky, just port over base color value
+        color = srgb_to_linear(baseColor.rgb);
     }
     else
     {
         // legacy shaders are still writng sRGB to gbuffer
-        diffuse.rgb = srgb_to_linear(diffuse.rgb);
+        baseColor.rgb = srgb_to_linear(baseColor.rgb);
         spec.rgb = srgb_to_linear(spec.rgb);
 
-        float envIntensity = norm.z;
-        norm.xyz           = getNorm(tc);
-
         float da          = clamp(dot(norm.xyz, light_dir.xyz), 0.0, 1.0);
 
-        sampleReflectionProbesLegacy(ambenv, glossenv, legacyenv, pos.xyz, norm.xyz, spec.a, envIntensity);
+        vec3 irradiance = vec3(0);
+        vec3 glossenv = vec3(0);
+        vec3 legacyenv = vec3(0);
 
+        sampleReflectionProbesLegacy(irradiance, glossenv, legacyenv, pos.xyz, norm.xyz, spec.a, envIntensity);
+        
         // use sky settings ambient or irradiance map sample, whichever is brighter
-        color = max(amblit, ambenv*ambocc);
+        irradiance = max(amblit, irradiance);
 
-        float ambient = min(abs(dot(norm.xyz, light_dir.xyz)), 1.0);
-        ambient *= 0.5;
-        ambient *= ambient;
-        ambient = (1.0 - ambient);
-        color.rgb *= ambient;
+        // apply lambertian IBL only (see pbrIbl)
+        color.rgb = irradiance * ambocc;
 
         vec3 sun_contrib = min(da, scol) * sunlit;
         color.rgb += sun_contrib;
-        color.rgb *= diffuse.rgb;
-
+        color.rgb *= baseColor.rgb;
+        
         vec3 refnormpersp = reflect(pos.xyz, norm.xyz);
 
         if (spec.a > 0.0)  // specular reflection
@@ -229,14 +224,14 @@ void main()
             applyGlossEnv(color, glossenv, spec, pos.xyz, norm.xyz);
         }
 
-        color.rgb = mix(color.rgb, diffuse.rgb, diffuse.a);
+        color.rgb = mix(color.rgb, baseColor.rgb, baseColor.a);
         
         if (envIntensity > 0.0)
         {  // add environment map
             applyLegacyEnv(color, legacyenv, spec, pos.xyz, norm.xyz, envIntensity);
         }
 
-        color = mix(atmosFragLightingLinear(color, additive, atten), fullbrightAtmosTransportFragLinear(color, additive, atten), diffuse.a);
+        color = mix(atmosFragLightingLinear(color, additive, atten), fullbrightAtmosTransportFragLinear(color, additive, atten), baseColor.a);
         color = scaleSoftClipFragLinear(color);
     }