From 617436b7cb9a574c08e49974046c330da1b706e0 Mon Sep 17 00:00:00 2001
From: RunitaiLinden <davep@lindenlab.com>
Date: Thu, 28 Mar 2024 14:06:11 -0500
Subject: #1046 Tweak auto-exposure to not underexpose bright scenes (#1084)

---
 .../shaders/class1/deferred/luminanceF.glsl            | 18 +++++++++++++++++-
 .../class1/deferred/postDeferredGammaCorrect.glsl      | 12 +++++++++++-
 2 files changed, 28 insertions(+), 2 deletions(-)

(limited to 'indra/newview/app_settings/shaders/class1/deferred')

diff --git a/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl b/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl
index c8afacf9bb..95b2f80e06 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl
@@ -34,6 +34,8 @@ in vec2 vary_fragcoord;
 
 uniform sampler2D diffuseRect;
 uniform sampler2D emissiveRect;
+uniform sampler2D normalMap;
+uniform float diffuse_luminance_scale;
 
 float lum(vec3 col)
 {
@@ -45,7 +47,21 @@ void main()
 {
     vec2 tc = vary_fragcoord*0.6+0.2;
     tc.y -= 0.1; // HACK - nudge exposure sample down a little bit to favor ground over sky
-    vec3 c = texture(diffuseRect, tc).rgb + texture(emissiveRect, tc).rgb;
+    vec3 c = texture(diffuseRect, tc).rgb;
+    
+    vec4  norm         = texture(normalMap, tc);
+
+    if (!GET_GBUFFER_FLAG(GBUFFER_FLAG_HAS_HDRI) &&
+        !GET_GBUFFER_FLAG(GBUFFER_FLAG_SKIP_ATMOS))
+    {
+        // Apply the diffuse luminance scale to objects but not the sky
+        // Prevents underexposing when looking at bright environments
+        // while still allowing for realistically bright skies.
+        c *= diffuse_luminance_scale;
+    }
+
+    c += texture(emissiveRect, tc).rgb;
+
     float L = lum(c);
     frag_color = vec4(max(L, 0.0));
 }
diff --git a/indra/newview/app_settings/shaders/class1/deferred/postDeferredGammaCorrect.glsl b/indra/newview/app_settings/shaders/class1/deferred/postDeferredGammaCorrect.glsl
index d89377326e..1629ed91c8 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/postDeferredGammaCorrect.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/postDeferredGammaCorrect.glsl
@@ -153,6 +153,15 @@ float noise(vec2 x) {
 
 //=============================
 
+void debugExposure(inout vec3 color)
+{
+    float exp_scale = texture(exposureMap, vec2(0.5,0.5)).r;
+    exp_scale *= 0.5;
+    if (abs(vary_fragcoord.y-exp_scale) < 0.01 && vary_fragcoord.x < 0.1)
+    {
+        color = vec3(1,0,0);
+    }
+}
 
 vec3 legacyGamma(vec3 color)
 {
@@ -181,7 +190,8 @@ void main()
     vec3 seed = (diff.rgb+vec3(1.0))*vec3(tc.xy, tc.x+tc.y);
     vec3 nz = vec3(noise(seed.rg), noise(seed.gb), noise(seed.rb));
     diff.rgb += nz*0.003;
-    
+
+    //debugExposure(diff.rgb);
     frag_color = max(diff, vec4(0));
 }
 
-- 
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