1 files changed, 21 insertions, 0 deletions
diff --git a/intern/cycles/kernel/osl/nodes/node_fresnel.h b/intern/cycles/kernel/osl/nodes/node_fresnel.h
new file mode 100644
index 00000000000..0c8a5276ede
--- /dev/null
+++ b/intern/cycles/kernel/osl/nodes/node_fresnel.h
@@ -0,0 +1,21 @@
+
+float fresnel_dielectric(vector Incoming, normal Normal, float eta)
+{
+	/* compute fresnel reflectance without explicitly computing
+	   the refracted direction */
+	float c = fabs(dot(Incoming, Normal));
+	float g = eta * eta - 1 + c * c;
+	float result;
+
+	if(g > 0) {
+		g = sqrt(g);
+		float A =(g - c)/(g + c);
+		float B =(c *(g + c)- 1)/(c *(g - c)+ 1);
+		result = 0.5 * A * A *(1 + B * B);
+	}
+	else
+		result = 1.0;  /* TIR (no refracted component) */
+
+	return result;
+}
+