[Bf-blender-cvs] [b03ac83] master: Cycles: Correction to glossy shaders not handling total internal reflection

[Sergey Sharybin]

Commit: b03ac8384389a4ad34bd6bcf0cc7be204c7ada9f
Author: Sergey Sharybin
Date:   Tue Feb 10 18:20:36 2015 +0500
Branches: master
https://developer.blender.org/rBb03ac8384389a4ad34bd6bcf0cc7be204c7ada9f

Cycles: Correction to glossy shaders not handling total internal reflection

The issue was caused by lack of check for whether fresnel term is actually
giving total internal reflection in refraction BSDFs. This lead to usage of
arbitrary vector of (0, 0, 0) as reflection, giving numeric issues in other
areas of the kernel.

This gives some visual changes of sharp reflection but it seems to be rather
proper now. Which also corresponds with rough glossy reflection with sharpness
set to 0.001 (previously it was totally different from sharpness of 0.0, which
is just weird).

===================================================================

M	intern/cycles/kernel/closure/bsdf_microfacet.h
M	intern/cycles/kernel/closure/bsdf_refraction.h

===================================================================

diff --git a/intern/cycles/kernel/closure/bsdf_microfacet.h b/intern/cycles/kernel/closure/bsdf_microfacet.h
index 9561885..20dced2 100644
--- a/intern/cycles/kernel/closure/bsdf_microfacet.h
+++ b/intern/cycles/kernel/closure/bsdf_microfacet.h
@@ -591,16 +591,16 @@ ccl_device int bsdf_microfacet_ggx_sample(KernelGlobals *kg, const ShaderClosure
 #ifdef __RAY_DIFFERENTIALS__
 			float3 dRdx, dRdy, dTdx, dTdy;
 #endif
-			float m_eta = sc->data2;
+			float m_eta = sc->data2, fresnel;
 			bool inside;
 
-			fresnel_dielectric(m_eta, m, I, &R, &T,
+			fresnel = fresnel_dielectric(m_eta, m, I, &R, &T,
 #ifdef __RAY_DIFFERENTIALS__
 				dIdx, dIdy, &dRdx, &dRdy, &dTdx, &dTdy,
 #endif
 				&inside);
 			
-			if(!inside) {
+			if(!inside && fresnel != 1.0f) {
 
 				*omega_in = T;
 #ifdef __RAY_DIFFERENTIALS__
@@ -945,16 +945,16 @@ ccl_device int bsdf_microfacet_beckmann_sample(KernelGlobals *kg, const ShaderCl
 #ifdef __RAY_DIFFERENTIALS__
 			float3 dRdx, dRdy, dTdx, dTdy;
 #endif
-			float m_eta = sc->data2;
+			float m_eta = sc->data2, fresnel;
 			bool inside;
 
-			fresnel_dielectric(m_eta, m, I, &R, &T,
+			fresnel = fresnel_dielectric(m_eta, m, I, &R, &T,
 #ifdef __RAY_DIFFERENTIALS__
 				dIdx, dIdy, &dRdx, &dRdy, &dTdx, &dTdy,
 #endif
 				&inside);
 
-			if(!inside) {
+			if(!inside && fresnel != 1.0f) {
 				*omega_in = T;
 
 #ifdef __RAY_DIFFERENTIALS__
diff --git a/intern/cycles/kernel/closure/bsdf_refraction.h b/intern/cycles/kernel/closure/bsdf_refraction.h
index c96ac62..02a0694 100644
--- a/intern/cycles/kernel/closure/bsdf_refraction.h
+++ b/intern/cycles/kernel/closure/bsdf_refraction.h
@@ -67,13 +67,14 @@ ccl_device int bsdf_refraction_sample(const ShaderClosure *sc, float3 Ng, float3
 	float3 dRdx, dRdy, dTdx, dTdy;
 #endif
 	bool inside;
-	fresnel_dielectric(m_eta, N, I, &R, &T,
+	float fresnel;
+	fresnel = fresnel_dielectric(m_eta, N, I, &R, &T,
 #ifdef __RAY_DIFFERENTIALS__
 		dIdx, dIdy, &dRdx, &dRdy, &dTdx, &dTdy,
 #endif
 		&inside);
 
-	if(!inside) {
+	if(!inside && fresnel != 1.0f) {
 		/* Some high number for MIS. */
 		*pdf = 1e6f;
 		*eval = make_float3(1e6f, 1e6f, 1e6f);