SL-19538 Followup -- fix for dynamic exposure having large gaps in it… (#157)

* SL-19538 Followup -- fix for dynamic exposure having large gaps in its luminance sampling.

* SL-19538 Followup -- review feedback changes.

2 files changed, 54 insertions, 36 deletions

diff --git a/indra/newview/app_settings/shaders/class1/deferred/exposureF.glsl b/indra/newview/app_settings/shaders/class1/deferred/exposureF.glsl
index 4c860cdde0..3eda2b9050 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/exposureF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/exposureF.glsl
@@ -29,7 +29,6 @@
 
 out vec4 frag_color;
 
-uniform sampler2D diffuseRect;
 uniform sampler2D emissiveRect;
 uniform sampler2D exposureMap;
 
@@ -46,45 +45,12 @@ float lum(vec3 col)
 
 void main() 
 {
-    float step = 1.0/16.0;
+    vec2 tc = vec2(0.5,0.5);
 
-    float start = step;
-    float end = 1.0-step;
-
-    float w = 0.0;
-
-    vec3 col;
-
-    //vec2 nz = noiseVec * step * 0.5;
-
-    for (float x = start; x <= end; x += step)
-    {
-        for (float y = start; y <= end; y += step)
-        {
-            vec2 tc = vec2(x,y); // + nz;
-            vec3 c = texture(diffuseRect, tc).rgb + texture(emissiveRect, tc).rgb;
-            float L = max(lum(c), 0.25);
-
-            float d = length(vec2(0.5)-tc);
-            d = 1.0-d;
-            d *= d;
-            d *= d;
-            d *= d;
-            L *= d;
-
-            w += L;
-
-            col += c * L;
-        }
-    }
-
-    col /= w;
-
-    float L = lum(col);
+    float L = textureLod(emissiveRect, tc, 8).r;
 
     float s = clamp(dynamic_exposure_params.x/L, dynamic_exposure_params.y, dynamic_exposure_params.z);
 
-
     float prev = texture(exposureMap, vec2(0.5,0.5)).r;
 
     s = mix(prev, s, min(dt*2.0*abs(prev-s), 0.04));
diff --git a/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl b/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl
new file mode 100644
index 0000000000..e63e666778
--- /dev/null
+++ b/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl
@@ -0,0 +1,52 @@
+/** 
+ * @file luminanceF.glsl
+ *
+ * $LicenseInfo:firstyear=2023&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2023, 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
+ * $/LicenseInfo$
+ */
+ 
+
+/*[EXTRA_CODE_HERE]*/
+
+// take a luminance sample of diffuseRect and emissiveRect 
+
+out vec4 frag_color;
+
+in vec2 vary_fragcoord;
+
+uniform sampler2D diffuseRect;
+uniform sampler2D emissiveRect;
+
+float lum(vec3 col)
+{
+    vec3 l = vec3(0.2126, 0.7152, 0.0722);
+    return dot(l, col);
+}
+
+void main() 
+{
+    vec2 tc = vary_fragcoord*0.6+0.2;
+    vec3 c = texture(diffuseRect, tc).rgb + texture(emissiveRect, tc).rgb;
+    float L = lum(c);
+
+    frag_color = vec4(L);
+}
+