2 files changed, 22 insertions, 9 deletions
diff --git a/indra/newview/app_settings/shaders/class1/deferred/materialF.glsl b/indra/newview/app_settings/shaders/class1/deferred/materialF.glsl
index a7dce5c7a5..e640c2d7ae 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/materialF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/materialF.glsl
@@ -276,20 +276,26 @@ void main()
 
     final_color.a = max(final_color.a, emissive_brightness);
 
-    // SL-11406 Fullbright: Object > Texture > Shininess > Environment Intensity
+    // SL-11406 Fullbright: Object > Texture > Shininess > Environment Intensity = 1
+    // NOTE: There are two shaders that are used depending on the EI byte value:
+    //     EI = 0        fullbright
+    //     EI > 0 .. 255 material
+    // When it is passed to us it is normalized.
     // We can either modify the output environment intensity
     //   OR
-    // adjust the final color via
+    // adjust the final color via:
     //     final_color *= 0.666666;
-    // We remap the environment intensity to simulate what non-EEP is doing.
+    // We remap the environment intensity to closely simulate what non-EEP is doing.
+    //    At midnight the brightness is exact.
+    //    At midday the brightness is very close.
     float ei = env_intensity*0.5 + 0.5;
     vec4 final_normal = vec4(abnormal, ei, 0.0);
     vec4 final_specular = spec;
     
     final_specular.a = specular_color.a;
 
-#if HAS_SPECULAR_MAP	
-	final_specular.a *= norm.a;
+#ifdef HAS_SPECULAR_MAP
+    final_specular.a *= norm.a;
     final_normal.z *= spec.a;
 #endif
 
@@ -323,11 +329,10 @@ void main()
 
 
     float da = dot(norm.xyz, normalize(light_dir.xyz));
-    // Dot product is guaranteed to be in -1 < dot() < +1 range for normalized vectors
+    // Dot product is guaranteed to be in -1 <= da <= +1 range for normalized vectors
     //    da = clamp(da, -1.0, 1.0);
 
-    float final_da = da;
-          final_da = clamp(final_da, 0.0, 1.0);
+    float final_da = clamp(da, 0.0, 1.0);
 
     float ambient = da;
     ambient *= 0.5;
@@ -465,3 +470,4 @@ vec3 post_atmo = color.rgb;
 #endif
 }
 
+
diff --git a/indra/newview/app_settings/shaders/class2/windlight/transportF.glsl b/indra/newview/app_settings/shaders/class2/windlight/transportF.glsl
index d2d839ed05..a06f4f22ad 100644
--- a/indra/newview/app_settings/shaders/class2/windlight/transportF.glsl
+++ b/indra/newview/app_settings/shaders/class2/windlight/transportF.glsl
@@ -51,7 +51,14 @@ vec3 atmosTransport(vec3 light)
 vec3 fullbrightAtmosTransport(vec3 light)
 {
     float brightness = dot(light.rgb * 0.5, vec3(0.3333)) + 0.1;
-    return atmosTransportFrag(light * 0.5, getAdditiveColor() * brightness, getAtmosAttenuation());
+    vec3 attenColor = atmosTransportFrag(light * 0.5, getAdditiveColor() * brightness, getAtmosAttenuation());
+
+    // attenColor is an accurate fog-attenuated result for any brightness
+    // But, the pre-EEP shader included a brightness-indexed lerp to a non-attenuated version
+    // of the color - effectively a fog 'burn-through' for very bright pixels. To more closely
+    // match the pre-EEP behavior, we'll also lerp to the pre-EEP color, based on overall brightness
+    float preEepBright = dot(light.rgb, vec3(0.3333));
+    retun mix(attenColor, (light.rgb + getAdditiveColor().rgb) * (2.0 - preEepBright), preEepBright * preEepBright);
 }
 
 vec3 fullbrightShinyAtmosTransport(vec3 light)