Cycles Hair: Two basic bair shaders added

A new hair bsdf node, with two closure options, is added. These closures allow the generation of the reflective and transmission components of hair. The node allows control of the highlight colour, roughness and angular shift.

Llimitations include:
-No glint or fresnel adjustments.
-The 'offset' is un-used when triangle primitives are used.

15 files changed, 515 insertions, 4 deletions

diff --git a/intern/cycles/blender/blender_shader.cpp b/intern/cycles/blender/blender_shader.cpp
index 5dfbd97366a..2007171642f 100644
--- a/intern/cycles/blender/blender_shader.cpp
+++ b/intern/cycles/blender/blender_shader.cpp
@@ -395,6 +395,19 @@ static ShaderNode *add_node(Scene *scene, BL::BlendData b_data, BL::Scene b_scen
 		}
 		node = toon;
 	}
+	else if (b_node.is_a(&RNA_ShaderNodeBsdfHair)) {
+		BL::ShaderNodeBsdfHair b_hair_node(b_node);
+		HairBsdfNode *hair = new HairBsdfNode();
+		switch(b_hair_node.component()) {
+			case BL::ShaderNodeBsdfHair::component_Reflection:
+				hair->component = ustring("Reflection");
+				break;
+			case BL::ShaderNodeBsdfHair::component_Transmission:
+				hair->component = ustring("Transmission");
+				break;
+		}
+		node = hair;
+	}
 	else if (b_node.is_a(&RNA_ShaderNodeBsdfTranslucent)) {
 		node = new TranslucentBsdfNode();
 	}
diff --git a/intern/cycles/kernel/CMakeLists.txt b/intern/cycles/kernel/CMakeLists.txt
index 9db05693fc3..eaa4e304ebb 100644
--- a/intern/cycles/kernel/CMakeLists.txt
+++ b/intern/cycles/kernel/CMakeLists.txt
@@ -67,6 +67,7 @@ set(SRC_CLOSURE_HEADERS
 	closure/bsdf_util.h
 	closure/bsdf_ward.h
 	closure/bsdf_westin.h
+	closure/bsdf_hair.h
 	closure/bssrdf.h
 	closure/emissive.h
 	closure/volume.h
diff --git a/intern/cycles/kernel/closure/bsdf.h b/intern/cycles/kernel/closure/bsdf.h
index d81bbebd5a8..86fea48760f 100644
--- a/intern/cycles/kernel/closure/bsdf.h
+++ b/intern/cycles/kernel/closure/bsdf.h
@@ -28,6 +28,7 @@
 #endif
 #include "../closure/bsdf_westin.h"
 #include "../closure/bsdf_toon.h"
+#include "../closure/bsdf_hair.h"
 #ifdef __SUBSURFACE__
 #include "../closure/bssrdf.h"
 #endif
@@ -114,6 +115,14 @@ __device int bsdf_sample(KernelGlobals *kg, const ShaderData *sd, const ShaderCl
 			label = bsdf_westin_sheen_sample(sc, sd->Ng, sd->I, sd->dI.dx, sd->dI.dy, randu, randv,
 				eval, omega_in, &domega_in->dx, &domega_in->dy, pdf);
 			break;
+		case CLOSURE_BSDF_HAIR_REFLECTION_ID:
+			label = bsdf_hair_reflection_sample(sc, sd->Ng, sd->I, sd->dI.dx, sd->dI.dy, randu, randv,
+				eval, omega_in, &domega_in->dx, &domega_in->dy, pdf);
+			break;
+		case CLOSURE_BSDF_HAIR_TRANSMISSION_ID:
+			label = bsdf_hair_transmission_sample(sc, sd->Ng, sd->I, sd->dI.dx, sd->dI.dy, randu, randv,
+				eval, omega_in, &domega_in->dx, &domega_in->dy, pdf);
+			break;
 #endif
 		default:
 			label = LABEL_NONE;
@@ -188,6 +197,12 @@ __device float3 bsdf_eval(KernelGlobals *kg, const ShaderData *sd, const ShaderC
 			case CLOSURE_BSDF_WESTIN_SHEEN_ID:
 				eval = bsdf_westin_sheen_eval_reflect(sc, sd->I, omega_in, pdf);
 				break;
+			case CLOSURE_BSDF_HAIR_REFLECTION_ID:
+				eval = bsdf_hair_reflection_eval_reflect(sc, sd->I, omega_in, pdf);
+				break;
+			case CLOSURE_BSDF_HAIR_TRANSMISSION_ID:
+				eval = bsdf_hair_transmission_eval_reflect(sc, sd->I, omega_in, pdf);
+				break;
 #endif
 			default:
 				eval = make_float3(0.0f, 0.0f, 0.0f);
@@ -244,6 +259,12 @@ __device float3 bsdf_eval(KernelGlobals *kg, const ShaderData *sd, const ShaderC
 			case CLOSURE_BSDF_WESTIN_SHEEN_ID:
 				eval = bsdf_westin_sheen_eval_transmit(sc, sd->I, omega_in, pdf);
 				break;
+			case CLOSURE_BSDF_HAIR_REFLECTION_ID:
+				eval = bsdf_hair_reflection_eval_transmit(sc, sd->I, omega_in, pdf);
+				break;
+			case CLOSURE_BSDF_HAIR_TRANSMISSION_ID:
+				eval = bsdf_hair_transmission_eval_transmit(sc, sd->I, omega_in, pdf);
+				break;
 #endif
 			default:
 				eval = make_float3(0.0f, 0.0f, 0.0f);
@@ -318,6 +339,10 @@ __device void bsdf_blur(KernelGlobals *kg, ShaderClosure *sc, float roughness)
 		case CLOSURE_BSDF_WESTIN_SHEEN_ID:
 			bsdf_westin_sheen_blur(sc, roughness);
 			break;
+		case CLOSURE_BSDF_HAIR_REFLECTION_ID:
+		case CLOSURE_BSDF_HAIR_TRANSMISSION_ID:
+			bsdf_hair_reflection_blur(sc, roughness);
+			break;
 #endif
 		default:
 			break;
diff --git a/intern/cycles/kernel/closure/bsdf_hair.h b/intern/cycles/kernel/closure/bsdf_hair.h
new file mode 100644
index 00000000000..5791598459c
--- /dev/null
+++ b/intern/cycles/kernel/closure/bsdf_hair.h
@@ -0,0 +1,279 @@
+/*
+ * Adapted from Open Shading Language with this license:
+ *
+ * Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
+ * All Rights Reserved.
+ *
+ * Modifications Copyright 2011, Blender Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * * Neither the name of Sony Pictures Imageworks nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __BSDF_HAIR_H__
+#define __BSDF_HAIR_H__
+
+CCL_NAMESPACE_BEGIN
+
+
+__device void bsdf_hair_reflection_blur(ShaderClosure *sc, float roughness)
+{
+}
+
+__device void bsdf_hair_transmission_blur(ShaderClosure *sc, float roughness)
+{
+}
+
+__device int bsdf_hair_reflection_setup(ShaderClosure *sc)
+{
+	sc->type = CLOSURE_BSDF_HAIR_REFLECTION_ID;
+	sc->data0 = clamp(sc->data0, 0.001f,1.0f);
+	sc->data1 = clamp(sc->data1, 0.001f,1.0f);
+	return SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_GLOSSY;
+}
+
+__device int bsdf_hair_transmission_setup(ShaderClosure *sc)
+{
+	sc->type = CLOSURE_BSDF_HAIR_TRANSMISSION_ID;
+	sc->data0 = clamp(sc->data0, 0.001f,1.0f);
+	sc->data1 = clamp(sc->data1, 0.001f,1.0f);
+	return SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_GLOSSY;
+}
+
+__device float3 bsdf_hair_reflection_eval_reflect(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
+{
+#ifdef __HAIR__
+	float offset = sc->offset;
+	float3 Tg = sc->T;
+#else
+	float offset = 0.0f;
+	float3 Tg = make_float3(1.0f,0.0f,0.0f);
+#endif
+	float roughness1 = sc->data0;
+	float roughness2 = sc->data1;
+
+	float Iz = dot(Tg, I);
+	float3 locy = normalize(I - Tg * Iz);
+	float3 locx = cross(locy, Tg);
+
+	float theta_r = M_PI_2_F - safe_acosf(Iz);
+
+	float omega_in_z = dot(Tg, omega_in);
+	float3 omega_in_y = normalize(omega_in - Tg * omega_in_z);
+
+	float theta_i = M_PI_2_F - safe_acosf(omega_in_z);
+	float cosphi_i = dot(omega_in_y, locy);
+
+	if(M_PI_2_F - fabsf(theta_i) < 0.001f || cosphi_i < 0.0f){
+		*pdf = 0.0f;
+		return make_float3(*pdf, *pdf, *pdf);
+	}
+
+	float phi_i = safe_acosf(cosphi_i) / roughness2;
+	phi_i = fabsf(phi_i) < M_PI_F ? phi_i : M_PI_F;
+	float costheta_i = cosf(theta_i);
+
+	float a_R = atan2f(((M_PI_2_F + theta_r) * 0.5f - offset) / roughness1, 1.0f);
+	float b_R = atan2f(((-M_PI_2_F + theta_r) * 0.5f - offset) / roughness1, 1.0f);
+
+	float theta_h = (theta_i + theta_r) * 0.5f;
+	float t = theta_h - offset;
+
+	float phi_pdf = cos(phi_i * 0.5f) * 0.25f / roughness2;
+	float theta_pdf = roughness1 / (2 * (t*t + roughness1*roughness1) * (a_R - b_R)* costheta_i);
+	*pdf = phi_pdf * theta_pdf;
+
+	return make_float3(*pdf, *pdf, *pdf);
+}
+
+__device float3 bsdf_hair_transmission_eval_reflect(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
+{
+	return make_float3(0.0f, 0.0f, 0.0f);
+}
+
+
+__device float3 bsdf_hair_reflection_eval_transmit(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
+{
+	return make_float3(0.0f, 0.0f, 0.0f);
+}
+
+__device float3 bsdf_hair_transmission_eval_transmit(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
+{
+#ifdef __HAIR__
+	float offset = sc->offset;
+	float3 Tg = sc->T;
+#else
+	float offset = 0.0f;
+	float3 Tg = make_float3(1.0f,0.0f,0.0f);
+#endif
+	float roughness1 = sc->data0;
+	float roughness2 = sc->data1;
+	float Iz = dot(Tg, I);
+	float3 locy = normalize(I - Tg * Iz);
+	float3 locx = cross(locy, Tg);
+
+	float theta_r = M_PI_2_F - safe_acosf(Iz);
+
+	float omega_in_z = dot(Tg, omega_in);
+	float3 omega_in_y = normalize(omega_in - Tg * omega_in_z);
+
+	float theta_i = M_PI_2_F - safe_acosf(omega_in_z);
+	float phi_i = safe_acosf(dot(omega_in_y, locy));
+
+	if(M_PI_2_F - fabsf(theta_i) < 0.001f){
+		*pdf = 0.0f;
+		return make_float3(*pdf, *pdf, *pdf);
+	}
+
+	float costheta_i = cosf(theta_i);
+
+	float a_TT = atan2f(((M_PI_2_F + theta_r)/2 - offset) / roughness1, 1.0f);
+	float b_TT = atan2f(((-M_PI_2_F + theta_r)/2 - offset) / roughness1, 1.0f);
+	float c_TT = 2 * atan2f(M_PI_2_F / roughness2, 1.0f);
+
+	float theta_h = (theta_i + theta_r) / 2;
+	float t = theta_h - offset;
+	float phi = fabsf(phi_i);
+
+	float p = M_PI_F - phi;
+	float theta_pdf = roughness1 / (2 * (t*t + roughness1 * roughness1) * (a_TT - b_TT)*costheta_i);
+	float phi_pdf = roughness2 / (c_TT * (p * p + roughness2 * roughness2));
+
+	*pdf = phi_pdf * theta_pdf;
+	return make_float3(*pdf, *pdf, *pdf);
+}
+
+__device int bsdf_hair_reflection_sample(const ShaderClosure *sc, float3 Ng, float3 I, float3 dIdx, float3 dIdy, float randu, float randv, float3 *eval, float3 *omega_in, float3 *domega_in_dx, float3 *domega_in_dy, float *pdf)
+{
+#ifdef __HAIR__
+	float offset = sc->offset;
+	float3 Tg = sc->T;
+#else
+	float offset = 0.0f;
+	float3 Tg = make_float3(1.0f,0.0f,0.0f);
+#endif
+	float roughness1 = sc->data0;
+	float roughness2 = sc->data1;
+	float Iz = dot(Tg, I);
+	float3 locy = normalize(I - Tg * Iz);
+	float3 locx = cross(locy, Tg);
+	float theta_r = M_PI_2_F - safe_acosf(Iz);
+
+	float a_R = atan2f(((M_PI_2_F + theta_r) * 0.5f - offset) / roughness1, 1.0f);
+	float b_R = atan2f(((-M_PI_2_F + theta_r) * 0.5f - offset) / roughness1, 1.0f);
+
+	float t = roughness1 * tanf(randu * (a_R - b_R) + b_R);
+
+	float theta_h = t + offset;
+	float theta_i = 2 * theta_h - theta_r;
+	float costheta_i = cosf(theta_i);
+	float sintheta_i = sinf(theta_i);
+
+	float phi = 2 * safe_asinf(1 - 2 * randv) * roughness2;
+
+	float phi_pdf = cos(phi * 0.5f) * 0.25f / roughness2;
+
+	float theta_pdf = roughness1 / (2 * (t*t + roughness1*roughness1) * (a_R - b_R)*costheta_i);
+
+	*omega_in =(cosf(phi) * costheta_i) * locy -
+			   (sinf(phi) * costheta_i) * locx +
+			   (            sintheta_i) * Tg;
+
+	//differentials - TODO: find a better approximation for the reflective bounce
+#ifdef __RAY_DIFFERENTIALS__
+	*domega_in_dx = 2 * dot(locy, dIdx) * locy - dIdx;
+	*domega_in_dy = 2 * dot(locy, dIdy) * locy - dIdy;
+#endif
+
+	*pdf = fabsf(phi_pdf * theta_pdf);
+	if(M_PI_2_F - fabsf(theta_i) < 0.001f)
+		*pdf = 0.0f;
+
+	*eval = make_float3(*pdf, *pdf, *pdf);
+
+	if(dot(locy, *omega_in) < 0.0f) {
+		return LABEL_REFLECT|LABEL_TRANSMIT|LABEL_GLOSSY;
+	}
+	
+	return LABEL_REFLECT|LABEL_GLOSSY;
+}
+
+__device int bsdf_hair_transmission_sample(const ShaderClosure *sc, float3 Ng, float3 I, float3 dIdx, float3 dIdy, float randu, float randv, float3 *eval, float3 *omega_in, float3 *domega_in_dx, float3 *domega_in_dy, float *pdf)
+{
+#ifdef __HAIR__
+	float offset = sc->offset;
+	float3 Tg = sc->T;
+#else
+	float offset = 0.0f;
+	float3 Tg = make_float3(1.0f,0.0f,0.0f);
+#endif
+	float roughness1 = sc->data0;
+	float roughness2 = sc->data1;
+	float Iz = dot(Tg, I);
+	float3 locy = normalize(I - Tg * Iz);
+	float3 locx = cross(locy, Tg);
+	float theta_r = M_PI_2_F - safe_acosf(Iz);
+
+	float a_TT = atan2f(((M_PI_2_F + theta_r)/2 - offset) / roughness1, 1.0f);
+	float b_TT = atan2f(((-M_PI_2_F + theta_r)/2 - offset) / roughness1, 1.0f);
+	float c_TT = 2 * atan2f(M_PI_2_F / roughness2, 1.0f);
+
+	float t = roughness1 * tanf(randu * (a_TT - b_TT) + b_TT);
+
+	float theta_h = t + offset;
+	float theta_i = 2 * theta_h - theta_r;
+	float costheta_i = cosf(theta_i);
+	float sintheta_i = sinf(theta_i);
+
+	float p = roughness2 * tanf(c_TT * (randv - 0.5f));
+	float phi = p + M_PI_F;
+	float theta_pdf = roughness1 / (2 * (t*t + roughness1*roughness1) * (a_TT - b_TT) * costheta_i);
+	float phi_pdf = roughness2 / (c_TT * (p * p + roughness2 * roughness2));
+
+	*omega_in =(cosf(phi) * costheta_i) * locy -
+			   (sinf(phi) * costheta_i) * locx +
+			   (            sintheta_i) * Tg;
+
+	//differentials - TODO: find a better approximation for the transmission bounce
+#ifdef __RAY_DIFFERENTIALS__
+	*domega_in_dx = 2 * dot(locy, dIdx) * locy - dIdx;
+	*domega_in_dy = 2 * dot(locy, dIdy) * locy - dIdy;
+#endif
+
+	*pdf = fabsf(phi_pdf * theta_pdf);
+	if(M_PI_2_F - fabsf(theta_i) < 0.001f){
+		*pdf = 0.0f;
+	}
+
+	*eval = make_float3(*pdf, *pdf, *pdf);
+
+	if(dot(locy, *omega_in) < 0.0f)
+		return LABEL_TRANSMIT|LABEL_GLOSSY;
+	
+	return LABEL_GLOSSY;
+}
+
+CCL_NAMESPACE_END
+
+#endif /* __BSDF_HAIR_H__ */
+
diff --git a/intern/cycles/kernel/kernel_shader.h b/intern/cycles/kernel/kernel_shader.h
index e8e9af64df6..bcc4c42c9cc 100644
--- a/intern/cycles/kernel/kernel_shader.h
+++ b/intern/cycles/kernel/kernel_shader.h
@@ -272,7 +272,7 @@ void shader_setup_from_sample(KernelGlobals *kg, ShaderData *sd,
 #ifdef __INSTANCING__
 	sd->object = object;
 #endif
-	/* currently no access to bvh prim index for strand sd->prim - this will cause errors with needs fixing*/
+	/* currently no access to bvh prim index for strand sd->prim*/
 	sd->prim = prim;
 #ifdef __UV__
 	sd->u = u;
diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index 98594df8b10..d039b708bd4 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -462,10 +462,14 @@ typedef struct ShaderClosure {
 	float data1;
 
 	float3 N;
-#if defined(__ANISOTROPIC__) || defined(__SUBSURFACE__)
+#if defined(__ANISOTROPIC__) || defined(__SUBSURFACE__) || defined(__HAIR__)
 	float3 T;
 #endif
 
+#ifdef __HAIR__
+	float offset;
+#endif
+
 #ifdef __OSL__
 	void *prim;
 #endif
diff --git a/intern/cycles/kernel/osl/osl_closures.cpp b/intern/cycles/kernel/osl/osl_closures.cpp
index 6a3f27fb7b1..221406a1716 100644
--- a/intern/cycles/kernel/osl/osl_closures.cpp
+++ b/intern/cycles/kernel/osl/osl_closures.cpp
@@ -54,6 +54,7 @@
 #include "closure/bsdf_ward.h"
 #include "closure/bsdf_westin.h"
 #include "closure/bsdf_toon.h"
+#include "closure/bsdf_hair.h"
 
 CCL_NAMESPACE_BEGIN
 
@@ -142,6 +143,32 @@ BSDF_CLOSURE_CLASS_BEGIN(MicrofacetBeckmannRefraction, microfacet_beckmann_refra
 	CLOSURE_FLOAT_PARAM(MicrofacetBeckmannRefractionClosure, sc.data1),
 BSDF_CLOSURE_CLASS_END(MicrofacetBeckmannRefraction, microfacet_beckmann_refraction)
 
+BSDF_CLOSURE_CLASS_BEGIN(HairReflection, hair_reflection, hair_reflection, LABEL_GLOSSY)
+	CLOSURE_FLOAT3_PARAM(HairReflectionClosure, sc.N),
+	CLOSURE_FLOAT_PARAM(HairReflectionClosure, sc.data0),
+	CLOSURE_FLOAT_PARAM(HairReflectionClosure, sc.data1),
+#ifdef __HAIR__
+	CLOSURE_FLOAT3_PARAM(HairReflectionClosure, sc.T),
+	CLOSURE_FLOAT_PARAM(HairReflectionClosure, sc.offset),
+#else
+	CLOSURE_FLOAT3_PARAM(HairReflectionClosure, sc.N),
+	CLOSURE_FLOAT_PARAM(HairReflectionClosure, sc.data1),
+#endif
+BSDF_CLOSURE_CLASS_END(HairReflection, hair_reflection)
+
+BSDF_CLOSURE_CLASS_BEGIN(HairTransmission, hair_transmission, hair_transmission, LABEL_GLOSSY)
+	CLOSURE_FLOAT3_PARAM(HairTransmissionClosure, sc.N),
+	CLOSURE_FLOAT_PARAM(HairTransmissionClosure, sc.data0),
+	CLOSURE_FLOAT_PARAM(HairTransmissionClosure, sc.data1),
+#ifdef __HAIR__
+	CLOSURE_FLOAT3_PARAM(HairReflectionClosure, sc.T),
+	CLOSURE_FLOAT_PARAM(HairReflectionClosure, sc.offset),
+#else
+	CLOSURE_FLOAT3_PARAM(HairReflectionClosure, sc.N),
+	CLOSURE_FLOAT_PARAM(HairReflectionClosure, sc.data1),
+#endif
+BSDF_CLOSURE_CLASS_END(HairTransmission, hair_transmission)
+
 /* Registration */
 
 static void generic_closure_setup(OSL::RendererServices *, int id, void *data)
@@ -225,6 +252,11 @@ void OSLShader::register_closures(OSLShadingSystem *ss_)
 		closure_bssrdf_cubic_extended_params(), closure_bssrdf_cubic_prepare);
 	register_closure(ss, "bssrdf_gaussian", id++,
 		closure_bssrdf_gaussian_extended_params(), closure_bssrdf_gaussian_prepare);
+
+	register_closure(ss, "hair_reflection", id++,
+		bsdf_hair_reflection_params(), bsdf_hair_reflection_prepare);
+	register_closure(ss, "hair_transmission", id++,
+		bsdf_hair_transmission_params(), bsdf_hair_transmission_prepare);
 }
 
 CCL_NAMESPACE_END
diff --git a/intern/cycles/kernel/osl/osl_shader.cpp b/intern/cycles/kernel/osl/osl_shader.cpp
index 9ff3797b50f..625ad263f7f 100644
--- a/intern/cycles/kernel/osl/osl_shader.cpp
+++ b/intern/cycles/kernel/osl/osl_shader.cpp
@@ -180,6 +180,10 @@ static void flatten_surface_closure_tree(ShaderData *sd, int path_flag,
 					sc.data1 = bsdf->sc.data1;
 					sc.prim = bsdf->sc.prim;
 
+#ifdef __HAIR__
+					sc.offset = bsdf->sc.offset;
+#endif
+
 					/* add */
 					if(sc.sample_weight > 1e-5f && sd->num_closure < MAX_CLOSURE) {
 						sd->closure[sd->num_closure++] = sc;
diff --git a/intern/cycles/kernel/shaders/CMakeLists.txt b/intern/cycles/kernel/shaders/CMakeLists.txt
index 660cfbce528..0f8542b0546 100644
--- a/intern/cycles/kernel/shaders/CMakeLists.txt
+++ b/intern/cycles/kernel/shaders/CMakeLists.txt
@@ -74,6 +74,7 @@ set(SRC_OSL
 	node_blackbody.osl
 	node_wave_texture.osl
 	node_wireframe.osl
+	node_hair_bsdf.osl
 )
 
 set(SRC_OSL_HEADERS
diff --git a/intern/cycles/kernel/shaders/node_hair_bsdf.osl b/intern/cycles/kernel/shaders/node_hair_bsdf.osl
new file mode 100644
index 00000000000..d1d7d0fb6a6
--- /dev/null
+++ b/intern/cycles/kernel/shaders/node_hair_bsdf.osl
@@ -0,0 +1,56 @@
+/*
+ * Copyright 2011, Blender Foundation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include "stdosl.h"
+
+shader node_hair_bsdf(
+    color Color = 0.8,
+    string component = "Reflection",
+	float Offset = 0.0,
+	float RoughnessU = 0.1,
+	float RoughnessV = 1.0,
+	normal Normal = Ng,
+	output closure color BSDF = 0)
+{
+	float IsStrand;
+	float roughnessh = clamp(RoughnessU, 0.001,1.0);
+	float roughnessv = clamp(RoughnessV, 0.001,1.0);
+	getattribute("geom:is_curve", IsStrand);
+
+    if (!IsStrand) {
+		if (backfacing())
+        	BSDF = transparent();
+    	else {
+    		if (component == "Reflection")
+    			BSDF = Color * hair_reflection(Normal, roughnessh, roughnessv, normalize(dPdv), 0.0);
+    		else
+    			BSDF = Color * hair_transmission(Normal, roughnessh, roughnessv, normalize(dPdv), 0.0);
+		}
+	}
+    else {
+		if (backfacing())
+        	BSDF = transparent();
+    	else {
+    		if (component == "Reflection")
+    			BSDF = Color * hair_reflection(Normal, roughnessh, roughnessv, dPdu, -Offset);
+    		else
+    			BSDF = Color * hair_transmission(Normal, roughnessh, roughnessv, dPdu, -Offset);
+		}
+	}
+}
+
diff --git a/intern/cycles/kernel/shaders/stdosl.h b/intern/cycles/kernel/shaders/stdosl.h
index 3ad2bbc0588..424ca335903 100644
--- a/intern/cycles/kernel/shaders/stdosl.h
+++ b/intern/cycles/kernel/shaders/stdosl.h
@@ -468,6 +468,9 @@ closure color ambient_occlusion() BUILTIN;
 closure color bssrdf_cubic(normal N, vector radius, float texture_blur, float sharpness) BUILTIN;
 closure color bssrdf_gaussian(normal N, vector radius, float texture_blur) BUILTIN;
 
+closure color hair_reflection(normal N, float roughnessu, float roughnessv, vector T, float offset) BUILTIN;
+closure color hair_transmission(normal N, float roughnessu, float roughnessv, vector T, float offset) BUILTIN;
+
 // Backwards compatibility
 closure color bssrdf_cubic(normal N, vector radius) BUILTIN;
 closure color bssrdf_gaussian(normal N, vector radius) BUILTIN;
diff --git a/intern/cycles/kernel/svm/svm_closure.h b/intern/cycles/kernel/svm/svm_closure.h
index 9a9aefa5b29..6d9c4e215e6 100644
--- a/intern/cycles/kernel/svm/svm_closure.h
+++ b/intern/cycles/kernel/svm/svm_closure.h
@@ -337,6 +337,46 @@ __device void svm_node_closure_bsdf(KernelGlobals *kg, ShaderData *sd, float *st
 			}
 			break;
 		}
+#ifdef __HAIR__
+		case CLOSURE_BSDF_HAIR_REFLECTION_ID:
+		case CLOSURE_BSDF_HAIR_TRANSMISSION_ID: {
+			
+			if(sd->flag & SD_BACKFACING && sd->segment != ~0) {
+				ShaderClosure *sc = svm_node_closure_get_bsdf(sd, mix_weight);
+				if(sc) {
+					sc->weight = make_float3(1.0f,1.0f,1.0f);
+					sc->N = N;
+					sd->flag |= bsdf_transparent_setup(sc);
+				}
+			}
+			else {
+				ShaderClosure *sc = &sd->closure[sd->num_closure];
+				sc = svm_node_closure_get_bsdf(sd, mix_weight);
+
+				if(sc) {
+					sc->N = N;
+					sc->data0 = param1;
+					sc->data1 = param2;
+					sc->offset = -stack_load_float(stack, data_node.z);
+					if(sd->segment == ~0) {
+						sc->T = normalize(sd->dPdv);
+						sc->offset = 0.0f;
+					}
+					else
+						sc->T = sd->dPdu;
+					if(type == CLOSURE_BSDF_HAIR_REFLECTION_ID) {
+						sd->flag |= bsdf_hair_reflection_setup(sc);
+					}
+					else {
+						sd->flag |= bsdf_hair_transmission_setup(sc);
+					}
+				}
+			}
+
+			break;
+		}
+#endif
+
 #ifdef __SUBSURFACE__
 		case CLOSURE_BSSRDF_COMPATIBLE_ID:
 		case CLOSURE_BSSRDF_CUBIC_ID:
diff --git a/intern/cycles/kernel/svm/svm_types.h b/intern/cycles/kernel/svm/svm_types.h
index e2b299e661d..50daf159f26 100644
--- a/intern/cycles/kernel/svm/svm_types.h
+++ b/intern/cycles/kernel/svm/svm_types.h
@@ -357,6 +357,8 @@ typedef enum ClosureType {
 	CLOSURE_BSDF_WESTIN_BACKSCATTER_ID,
 	CLOSURE_BSDF_PHONG_RAMP_ID,
 	CLOSURE_BSDF_GLOSSY_TOON_ID,
+	CLOSURE_BSDF_HAIR_REFLECTION_ID,
+
 	
 	/* Transmission */
 	CLOSURE_BSDF_TRANSMISSION_ID,
@@ -367,6 +369,8 @@ typedef enum ClosureType {
 	CLOSURE_BSDF_MICROFACET_BECKMANN_GLASS_ID,
 	CLOSURE_BSDF_MICROFACET_GGX_GLASS_ID,
 	CLOSURE_BSDF_SHARP_GLASS_ID,
+	CLOSURE_BSDF_HAIR_TRANSMISSION_ID,
+
 	
 	/* Special cases */
 	CLOSURE_BSDF_BSSRDF_ID,
@@ -395,8 +399,8 @@ typedef enum ClosureType {
 /* watch this, being lazy with memory usage */
 #define CLOSURE_IS_BSDF(type) (type <= CLOSURE_BSDF_TRANSPARENT_ID)
 #define CLOSURE_IS_BSDF_DIFFUSE(type) (type >= CLOSURE_BSDF_DIFFUSE_ID && type <= CLOSURE_BSDF_DIFFUSE_TOON_ID)
-#define CLOSURE_IS_BSDF_GLOSSY(type) (type >= CLOSURE_BSDF_GLOSSY_ID && type <= CLOSURE_BSDF_GLOSSY_TOON_ID)
-#define CLOSURE_IS_BSDF_TRANSMISSION(type) (type >= CLOSURE_BSDF_TRANSMISSION_ID && type <= CLOSURE_BSDF_SHARP_GLASS_ID)
+#define CLOSURE_IS_BSDF_GLOSSY(type) (type >= CLOSURE_BSDF_GLOSSY_ID && type <= CLOSURE_BSDF_HAIR_REFLECTION_ID)
+#define CLOSURE_IS_BSDF_TRANSMISSION(type) (type >= CLOSURE_BSDF_TRANSMISSION_ID && type <= CLOSURE_BSDF_HAIR_TRANSMISSION_ID)
 #define CLOSURE_IS_BSDF_BSSRDF(type) (type == CLOSURE_BSDF_BSSRDF_ID)
 #define CLOSURE_IS_BSSRDF(type) (type >= CLOSURE_BSSRDF_COMPATIBLE_ID && type <= CLOSURE_BSSRDF_GAUSSIAN_ID)
 #define CLOSURE_IS_VOLUME(type) (type >= CLOSURE_VOLUME_ID && type <= CLOSURE_VOLUME_ISOTROPIC_ID)
diff --git a/intern/cycles/render/nodes.cpp b/intern/cycles/render/nodes.cpp
index 30f51728e1b..70cb5613e61 100644
--- a/intern/cycles/render/nodes.cpp
+++ b/intern/cycles/render/nodes.cpp
@@ -1950,6 +1950,46 @@ void IsotropicVolumeNode::compile(OSLCompiler& compiler)
 	compiler.add(this, "node_isotropic_volume");
 }
 
+/* Hair BSDF Closure */
+
+static ShaderEnum hair_component_init()
+{
+	ShaderEnum enm;
+
+	enm.insert("Reflection", CLOSURE_BSDF_HAIR_REFLECTION_ID);
+	enm.insert("Transmission", CLOSURE_BSDF_HAIR_TRANSMISSION_ID);
+	
+
+	return enm;
+}
+
+ShaderEnum HairBsdfNode::component_enum = hair_component_init();
+
+HairBsdfNode::HairBsdfNode()
+{
+	component = ustring("Reflection");
+
+	add_input("Offset", SHADER_SOCKET_FLOAT);
+	add_input("RoughnessU", SHADER_SOCKET_FLOAT);
+	add_input("RoughnessV", SHADER_SOCKET_FLOAT);
+
+}
+
+void HairBsdfNode::compile(SVMCompiler& compiler)
+{
+	closure = (ClosureType)component_enum[component];
+
+	BsdfNode::compile(compiler, input("RoughnessU"), input("RoughnessV"), input("Offset"));
+}
+
+void HairBsdfNode::compile(OSLCompiler& compiler)
+{
+	compiler.parameter("component", component);
+
+	compiler.add(this, "node_hair_bsdf");
+
+}
+
 /* Geometry */
 
 GeometryNode::GeometryNode()
diff --git a/intern/cycles/render/nodes.h b/intern/cycles/render/nodes.h
index 50338ddd5c0..d58c6633a41 100644
--- a/intern/cycles/render/nodes.h
+++ b/intern/cycles/render/nodes.h
@@ -321,6 +321,15 @@ public:
 	SHADER_NODE_CLASS(IsotropicVolumeNode)
 };
 
+class HairBsdfNode : public BsdfNode {
+public:
+	SHADER_NODE_CLASS(HairBsdfNode)
+
+	ustring component;
+	static ShaderEnum component_enum;
+
+};
+
 class GeometryNode : public ShaderNode {
 public:
 	SHADER_NODE_CLASS(GeometryNode)