Cycles / OSL: Add a conductive fresnel shader template.

This adds a fresnel conductive OSL preset to the Text Editor. Based on a patch by Lukas Stockner.
Differential revision: https://developer.blender.org/D145

See the differential for details.

1 files changed, 9 insertions, 7 deletions

diff --git a/intern/cycles/kernel/closure/bsdf_util.h b/intern/cycles/kernel/closure/bsdf_util.h
index b3dcb9dcc38..6851dca309b 100644
--- a/intern/cycles/kernel/closure/bsdf_util.h
+++ b/intern/cycles/kernel/closure/bsdf_util.h
@@ -111,14 +111,16 @@ ccl_device float fresnel_dielectric_cos(float cosi, float eta)
 	return 1.0f; // TIR(no refracted component)
 }
 
-ccl_device float fresnel_conductor(float cosi, float eta, float k)
+ccl_device float3 fresnel_conductor(float cosi, const float3 eta, const float3 k)
 {
-	float tmp_f = eta * eta + k * k;
-	float tmp = tmp_f * cosi * cosi;
-	float Rparl2 = (tmp - (2.0f * eta * cosi) + 1)/
-	               (tmp + (2.0f * eta * cosi) + 1);
-	float Rperp2 = (tmp_f - (2.0f * eta * cosi) + cosi * cosi)/
-	               (tmp_f + (2.0f * eta * cosi) + cosi * cosi);
+	float3 cosi2 = make_float3(cosi*cosi);
+	float3 one = make_float3(1.0f, 1.0f, 1.0f);
+	float3 tmp_f = eta * eta + k * k;
+	float3 tmp = tmp_f * cosi2;
+	float3 Rparl2 = (tmp - (2.0f * eta * cosi) + one) /
+					(tmp + (2.0f * eta * cosi) + one);
+	float3 Rperp2 = (tmp_f - (2.0f * eta * cosi) + cosi2) /
+					(tmp_f + (2.0f * eta * cosi) + cosi2);
 	return(Rparl2 + Rperp2) * 0.5f;
 }