From 5dcb84d1b52f14c3e907c1a3642ab87cbae161e6 Mon Sep 17 00:00:00 2001
From: Rye Mutt <rye@alchemyviewer.org>
Date: Fri, 22 Sep 2023 22:15:07 -0400
Subject: [PATCH] Multiscatter IBL
---
.../shaders/class1/deferred/deferredUtil.glsl | 24 +++++++++++++------
.../shaders/class1/deferred/genbrdflutF.glsl | 2 +-
2 files changed, 18 insertions(+), 8 deletions(-)
diff --git a/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl b/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl
index c8eaba64182..46ce7d66526 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/deferredUtil.glsl
@@ -375,6 +375,12 @@ vec2 BRDF(float NoV, float roughness)
return texture(brdfLut, vec2(NoV, roughness)).rg;
}
+// Lagarde and de Rousiers 2014, "Moving Frostbite to PBR"
+float computeSpecularAO(float NoV, float ao, float roughness)
+{
+ return clamp(pow(NoV + ao, exp2(-16.0 * roughness - 1.0)) - 1.0 + ao, 0.0, 1.0);
+}
+
// set colorDiffuse and colorSpec to the results of GLTF PBR style IBL
vec3 pbrIbl(vec3 diffuseColor,
vec3 specularColor,
@@ -386,16 +392,20 @@ vec3 pbrIbl(vec3 diffuseColor,
out vec3 specContrib)
{
// retrieve a scale and bias to F0. See [1], Figure 3
- vec2 brdf = BRDF(clamp(nv, 0, 1), 1.0-perceptualRough);
- vec3 diffuseLight = irradiance;
- vec3 specularLight = radiance;
+ vec2 brdf = BRDF(clamp(nv, 0, 1), 1.0-perceptualRough);
+ vec3 diffuseLight = irradiance;
+ vec3 specularLight = radiance;
- vec3 diffuse = diffuseLight * diffuseColor;
- vec3 specular = specularLight * (specularColor * brdf.x + brdf.y);
+ vec3 energy = mix(brdf.xxx, brdf.yyy, specularColor);
+
+ vec3 diffuse = diffuseLight * diffuseColor * (1.0 - energy);
+ vec3 specular = specularLight * energy;
+
+ specular *= computeSpecularAO(nv, ao, perceptualRough * perceptualRough) * (1.0 + specularColor * (1.0 / brdf.y - 1.0));
- specContrib = specular * ao;
+ specContrib = specular;
- return (diffuse + specular) * ao;
+ return (diffuse * ao) + specular;
}
vec3 pbrIbl(vec3 diffuseColor,
diff --git a/indra/newview/app_settings/shaders/class1/deferred/genbrdflutF.glsl b/indra/newview/app_settings/shaders/class1/deferred/genbrdflutF.glsl
index e40d070268e..df0d21b4323 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/genbrdflutF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/genbrdflutF.glsl
@@ -129,7 +129,7 @@ vec2 BRDF(float NoV, float roughness)
float G = G_SchlicksmithGGX(dotNL, dotNV, roughness);
float G_Vis = (G * dotVH) / (dotNH * dotNV);
float Fc = pow(1.0 - dotVH, 5.0);
- LUT += vec2((1.0 - Fc) * G_Vis, Fc * G_Vis);
+ LUT += vec2(Fc * G_Vis, G_Vis);
}
}
return LUT / float(NUM_SAMPLES);
--
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