SL-17702: PBR: Use legacy attenuation for point lights

3 files changed, 26 insertions, 27 deletions

diff --git a/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl b/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl
index d1b9418ee9..a49713afce 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl
@@ -48,6 +48,14 @@ const float ONE_OVER_PI = 0.3183098861;
 
 vec3 srgb_to_linear(vec3 cs);
 
+float calcLegacyDistanceAttenuation(float distance, float falloff)
+{
+    float dist_atten = 1.0 - clamp((distance + falloff)/(1.0 + falloff), 0.0, 1.0);
+    dist_atten *= dist_atten;
+    dist_atten *= 2.0;
+    return dist_atten;
+}
+
 // In:
 //   lv  unnormalized surface to light vector
 //   n   normal of the surface
diff --git a/indra/newview/app_settings/shaders/class3/deferred/multiPointLightF.glsl b/indra/newview/app_settings/shaders/class3/deferred/multiPointLightF.glsl
index d8e1bba5d8..98a03c2aaa 100644
--- a/indra/newview/app_settings/shaders/class3/deferred/multiPointLightF.glsl
+++ b/indra/newview/app_settings/shaders/class3/deferred/multiPointLightF.glsl
@@ -60,6 +60,7 @@ VARYING vec4 vary_fragcoord;
 vec3 BRDFLambertian( vec3 reflect0, vec3 reflect90, vec3 c_diff, float specWeight, float vh );
 vec3 BRDFSpecularGGX( vec3 reflect0, vec3 reflect90, float alphaRoughness, float specWeight, float vh, float nl, float nv, float nh );
 void calcHalfVectors(vec3 lv, vec3 n, vec3 v, out vec3 h, out vec3 l, out float nh, out float nl, out float nv, out float vh, out float lightDist);
+float calcLegacyDistanceAttenuation(float distance, float falloff);
 vec3 getLightIntensityPoint(vec3 lightColor, float lightRange, float lightDistance);
 vec4 getPosition(vec2 pos_screen);
 vec4 getNormalEnvIntensityFlags(vec2 screenpos, out vec3 n, out float envIntensity);
@@ -108,12 +109,11 @@ void main()
             if (nl > 0.0)
             {
                 float dist = lightDist / lightSize;
-                float dist_atten = 1.0 - (dist + falloff)/(1.0 + falloff);
-                dist_atten *= dist_atten;
-                dist_atten *= 2.0;
-                vec3 intensity = dist_atten * getLightIntensityPoint(lightColor, lightSize, lightDist);
-                colorDiffuse += intensity * nl * BRDFLambertian (reflect0, reflect90, c_diff    , specWeight, vh);
-                colorSpec    += intensity * nl * BRDFSpecularGGX(reflect0, reflect90, alphaRough, specWeight, vh, nl, nv, nh);
+                float dist_atten = calcLegacyDistanceAttenuation(dist, falloff);
+
+                vec3 intensity = dist_atten * nl * lightColor;
+                colorDiffuse += intensity * BRDFLambertian (reflect0, reflect90, c_diff    , specWeight, vh);
+                colorSpec    += intensity * BRDFSpecularGGX(reflect0, reflect90, alphaRough, specWeight, vh, nl, nv, nh);
             }
         }
 
@@ -146,13 +146,7 @@ void main()
                     calcHalfVectors(lv, n, v, h, l, nh, nl, nv, vh, lightDist);
 
                     float fa         = light_col[i].a + 1.0;
-                    float dist_atten = clamp(1.0 - (dist - 1.0 * (1.0 - fa)) / fa, 0.0, 1.0);
-                    dist_atten *= dist_atten;
-
-                    // Tweak falloff slightly to match pre-EEP attenuation
-                    // NOTE: this magic number also shows up in a great many other places, search for dist_atten *= to audit
-                    dist_atten *= 2.0;
-
+                    float dist_atten = calcLegacyDistanceAttenuation(dist, fa);
                     dist_atten *= noise;
 
                     float lit = nl * dist_atten;
diff --git a/indra/newview/app_settings/shaders/class3/deferred/pointLightF.glsl b/indra/newview/app_settings/shaders/class3/deferred/pointLightF.glsl
index a1298a8409..d65a53b6d3 100644
--- a/indra/newview/app_settings/shaders/class3/deferred/pointLightF.glsl
+++ b/indra/newview/app_settings/shaders/class3/deferred/pointLightF.glsl
@@ -65,6 +65,7 @@ uniform vec4 viewport;
 vec3 BRDFLambertian( vec3 reflect0, vec3 reflect90, vec3 c_diff, float specWeight, float vh );
 vec3 BRDFSpecularGGX( vec3 reflect0, vec3 reflect90, float alphaRoughness, float specWeight, float vh, float nl, float nv, float nh );
 void calcHalfVectors(vec3 lv, vec3 n, vec3 v, out vec3 h, out vec3 l, out float nh, out float nl, out float nv, out float vh, out float lightDist);
+float calcLegacyDistanceAttenuation(float distance, float falloff);
 vec3 getLightIntensityPoint(vec3 lightColor, float lightRange, float lightDistance);
 vec4 getNormalEnvIntensityFlags(vec2 screenpos, out vec3 n, out float envIntensity);
 vec4 getPosition(vec2 pos_screen);
@@ -91,10 +92,12 @@ void main()
     float nh, nl, nv, vh, lightDist;
     calcHalfVectors(lv, n, v, h, l, nh, nl, nv, vh, lightDist);
 
+    if (lightDist >= size)
+    {
+        discard;
+    }
     float dist = lightDist / size;
-    float dist_atten = 1.0 - (dist + falloff)/(1.0 + falloff);
-    dist_atten *= dist_atten;
-    dist_atten *= 2.0;
+    float dist_atten = calcLegacyDistanceAttenuation(dist, falloff);
 
     if (GET_GBUFFER_FLAG(GBUFFER_FLAG_HAS_PBR))
     {
@@ -102,6 +105,8 @@ void main()
         vec3 colorSpec     = vec3(0);
         vec3 colorEmissive = spec.rgb; // PBR sRGB Emissive.  See: pbropaqueF.glsl
         vec3 packedORM     = texture2DRect(emissiveRect, tc).rgb; // PBR linear packed Occlusion, Roughness, Metal. See: pbropaqueF.glsl
+        float lightSize    = size;
+        vec3 lightColor    = color;
 
         vec3 c_diff, reflect0, reflect90;
         float alphaRough, specWeight;
@@ -109,26 +114,18 @@ void main()
 
         if (nl > 0.0)
         {
-            vec3 intensity = dist_atten * getLightIntensityPoint(color, size, lightDist);
-            colorDiffuse += intensity * nl * BRDFLambertian (reflect0, reflect90, c_diff    , specWeight, vh);
-            colorSpec    += intensity * nl * BRDFSpecularGGX(reflect0, reflect90, alphaRough, specWeight, vh, nl, nv, nh);
+            vec3 intensity = dist_atten * nl * lightColor; // Legacy attenuation
+            colorDiffuse += intensity * BRDFLambertian (reflect0, reflect90, c_diff    , specWeight, vh);
+            colorSpec    += intensity * BRDFSpecularGGX(reflect0, reflect90, alphaRough, specWeight, vh, nl, nv, nh);
         }
 
 #if DEBUG_PBR_LIGHT_TYPE
         colorDiffuse = vec3(0,0,0.5); colorSpec = vec3(0);
 #endif
-
         final_color = colorDiffuse + colorSpec;
     }
     else
     {
-        float dist = lightDist;
-        if (dist >= size)
-        {
-            discard;
-        }
-        dist /= size;
-
         if (nl < 0.0)
         {
             discard;