Commit: 3ed1e08f66feffbf554656d3882e77321e8a0b09
Author: Pascal Schoen
Date: Tue Nov 15 10:53:30 2016 +0100
Branches: cycles_disney_bsdf_transmittance
https://developer.blender.org/rB3ed1e08f66feffbf554656d3882e77321e8a0b09
Implemented the specular transmission part of the thin surface
approximation.
===================================================================
M intern/cycles/kernel/shaders/node_disney_bsdf.osl
M intern/cycles/kernel/svm/svm_closure.h
===================================================================
diff --git a/intern/cycles/kernel/shaders/node_disney_bsdf.osl
b/intern/cycles/kernel/shaders/node_disney_bsdf.osl
index 9b1bd72..8b5bacb 100644
--- a/intern/cycles/kernel/shaders/node_disney_bsdf.osl
+++ b/intern/cycles/kernel/shaders/node_disney_bsdf.osl
@@ -108,20 +108,23 @@ shader node_disney_bsdf(
if (transp > 1e-5) {
color Cspec0 = BaseColor * SpecularTint + color(1.0, 1.0, 1.0)
* (1.0 - SpecularTint);
- float eta = backfacing() ? 1.0 / f : f;
+ float eta = (backfacing() && (surface_type == "Solid Surface"))
? 1.0 / f : f;
- if (distribution == "GGX" || Roughness <= 5e-2) {
+ if (distribution == "GGX" || Roughness <= 5e-2 || surface_type
== "Thin Surface") {
float cosNO = dot(Normal, I);
float Fr = fresnel_dielectric_cos(cosNO, eta);
- float refl_roughness = Roughness;
- if (Roughness <= 1e-2)
- refl_roughness = 0.0;
+ float refl_roughness = Roughness;
+ if (Roughness <= 1e-2)
+ refl_roughness = 0.0;
float refraction_roughness = refl_roughness;
if (distribution == "GGX")
refraction_roughness = 1.0 - (1.0 -
refl_roughness) * (1.0 - RefractionRoughness);
+ if (surface_type == "Thin Surface")
+ refraction_roughness = refraction_roughness *
(0.65 * eta - 0.35);
+
BSDF = BSDF + transp * (Fr *
microfacet_ggx_fresnel(Normal, refl_roughness * refl_roughness, eta, BaseColor,
Cspec0) +
(1.0 - Fr) * BaseColor *
microfacet_ggx_refraction(Normal, refraction_roughness * refraction_roughness,
eta));
} else {
diff --git a/intern/cycles/kernel/svm/svm_closure.h
b/intern/cycles/kernel/svm/svm_closure.h
index d4b6b90..6e75aee 100644
--- a/intern/cycles/kernel/svm/svm_closure.h
+++ b/intern/cycles/kernel/svm/svm_closure.h
@@ -115,7 +115,7 @@ ccl_device void svm_node_closure_bsdf(KernelGlobals *kg,
ShaderData *sd, float *
T = rotate_around_axis(T, N,
anisotropic_rotation * M_2PI_F);
/* calculate ior */
- float ior = (ccl_fetch(sd, flag) & SD_BACKFACING) ?
1.0f / eta : eta;
+ float ior = ((ccl_fetch(sd, flag) & SD_BACKFACING) &&
(surface_type == SOLID_SURFACE)) ? 1.0f / eta : eta;
// calculate fresnel for refraction
float cosNO = dot(N, ccl_fetch(sd, I));
@@ -369,7 +369,7 @@ ccl_device void svm_node_closure_bsdf(KernelGlobals *kg,
ShaderData *sd, float *
float3 glass_weight = weight *
spec_transp;
float3 cspec0 = base_color *
specular_tint + make_float3(1.0f, 1.0f, 1.0f) * (1.0f - specular_tint);
- if(roughness <= 5e-2f || distribution
== CLOSURE_BSDF_MICROFACET_GGX_GLASS_ID) { /* use single-scatter GGX */
+ if(roughness <= 5e-2f || distribution
== CLOSURE_BSDF_MICROFACET_GGX_GLASS_ID || surface_type == THIN_SURFACE) { /*
use single-scatter GGX */
float refl_roughness =
roughness;
/* reflection */
@@ -431,6 +431,14 @@ ccl_device void svm_node_closure_bsdf(KernelGlobals *kg,
ShaderData *sd, float *
else
refraction_roughness = refl_roughness;
+ /* Remap the
roughness for thin surfaces as introduced in the 2015 Disney paper:
+ *
+ * Extending
the Disney BRDF to a BSDF with Integrated Subsurface Scattering
+ * Burley,
Brent (Walt Disney Animation Studios) */
+ if(surface_type
== THIN_SURFACE) {
+
refraction_roughness *= 0.65f * ior - 0.35f;
+ }
+
bsdf->alpha_x =
refraction_roughness * refraction_roughness;
bsdf->alpha_y =
refraction_roughness * refraction_roughness;
bsdf->ior = ior;
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