[Shaders/Cook-Torrance] Made use of Brian Karis' Fresnel optimization

- In regards to the removed artifacts, it has been deemed better than the current calculation - This may still need further investigation as to why the artifacts appeared - Related to issue #16
Razakhel · Sep 29, 2020 · 5188f04 · 5188f04
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commit 5188f04
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Showing 2 changed files with 4 additions and 8 deletions.
diff --git a/shaders/cook-torrance.frag b/shaders/cook-torrance.frag
@@ -62,10 +62,8 @@ float computeNormalDistrib(vec3 normal, vec3 halfVec, float roughness) {
 
 // Fresnel: Shlick
 vec3 computeFresnel(float cosTheta, vec3 baseReflectivity) {
-  // Seemingly optimized version:
-  //    pow(2.0, (-5.55473 * cosTheta - 6.98316) * cosTheta)
-  // From: http://blog.selfshadow.com/publications/s2013-shading-course/karis/s2013_pbs_epic_notes_v2.pdf
-  return baseReflectivity + (1.0 - baseReflectivity) * pow(1.0 - cosTheta, 5.0);
+  // Optimized exponent version, from: http://blog.selfshadow.com/publications/s2013-shading-course/karis/s2013_pbs_epic_notes_v2.pdf
+  return baseReflectivity + (1.0 - baseReflectivity) * pow(2.0, (-5.55473 * cosTheta - 6.98316) * cosTheta);
 }
 
 // Shlick-Beckmann for Geometry part

diff --git a/shaders/opengles3/cook-torrance.frag b/shaders/opengles3/cook-torrance.frag
@@ -65,10 +65,8 @@ float computeNormalDistrib(vec3 normal, vec3 halfVec, float roughness) {
 
 // Fresnel: Shlick
 vec3 computeFresnel(float cosTheta, vec3 baseReflectivity) {
-  // Seemingly optimized version:
-  //    pow(2.0, (-5.55473 * cosTheta - 6.98316) * cosTheta)
-  // From: http://blog.selfshadow.com/publications/s2013-shading-course/karis/s2013_pbs_epic_notes_v2.pdf
-  return baseReflectivity + (1.0 - baseReflectivity) * pow(1.0 - cosTheta, 5.0);
+  // Optimized exponent version, from: http://blog.selfshadow.com/publications/s2013-shading-course/karis/s2013_pbs_epic_notes_v2.pdf
+  return baseReflectivity + (1.0 - baseReflectivity) * pow(2.0, (-5.55473 * cosTheta - 6.98316) * cosTheta);
 }
 
 // Shlick-Beckmann for Geometry part