Cycles: glossy and anisotropic BSDF changes

* Anisotropic BSDF now supports GGX and Beckmann distributions, Ward has been
  removed because other distributions are superior.
* GGX is now the default distribution for all glossy and anisotropic nodes,
  since it looks good, has low noise and is fast to evaluate.
* Ashikhmin-Shirley is now available in the Glossy BSDF.

4 files changed, 35 insertions, 212 deletions

diff --git a/intern/cycles/kernel/closure/bsdf.h b/intern/cycles/kernel/closure/bsdf.h
index 371d0bfa8ea..8ddf4971909 100644
--- a/intern/cycles/kernel/closure/bsdf.h
+++ b/intern/cycles/kernel/closure/bsdf.h
@@ -24,7 +24,6 @@
 #include "../closure/bsdf_refraction.h"
 #include "../closure/bsdf_transparent.h"
 #ifdef __ANISOTROPIC__
-#include "../closure/bsdf_ward.h"
 #include "../closure/bsdf_ashikhmin_shirley.h"
 #endif
 #include "../closure/bsdf_westin.h"
@@ -84,21 +83,20 @@ ccl_device int bsdf_sample(KernelGlobals *kg, const ShaderData *sd, const Shader
 				eval, omega_in, &domega_in->dx, &domega_in->dy, pdf);
 			break;
 		case CLOSURE_BSDF_MICROFACET_GGX_ID:
+		case CLOSURE_BSDF_MICROFACET_GGX_ANISO_ID:
 		case CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID:
 			label = bsdf_microfacet_ggx_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_MICROFACET_BECKMANN_ID:
+		case CLOSURE_BSDF_MICROFACET_BECKMANN_ANISO_ID:
 		case CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID:
 			label = bsdf_microfacet_beckmann_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;
 #ifdef __ANISOTROPIC__
-		case CLOSURE_BSDF_WARD_ID:
-			label = bsdf_ward_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_ASHIKHMIN_SHIRLEY_ID:
+		case CLOSURE_BSDF_ASHIKHMIN_SHIRLEY_ANISO_ID:
 			label = bsdf_ashikhmin_shirley_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;
@@ -183,18 +181,18 @@ ccl_device float3 bsdf_eval(KernelGlobals *kg, const ShaderData *sd, const Shade
 				eval = bsdf_transparent_eval_reflect(sc, sd->I, omega_in, pdf);
 				break;
 			case CLOSURE_BSDF_MICROFACET_GGX_ID:
+			case CLOSURE_BSDF_MICROFACET_GGX_ANISO_ID:
 			case CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID:
 				eval = bsdf_microfacet_ggx_eval_reflect(sc, sd->I, omega_in, pdf);
 				break;
 			case CLOSURE_BSDF_MICROFACET_BECKMANN_ID:
+			case CLOSURE_BSDF_MICROFACET_BECKMANN_ANISO_ID:
 			case CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID:
 				eval = bsdf_microfacet_beckmann_eval_reflect(sc, sd->I, omega_in, pdf);
 				break;
 #ifdef __ANISOTROPIC__
-			case CLOSURE_BSDF_WARD_ID:
-				eval = bsdf_ward_eval_reflect(sc, sd->I, omega_in, pdf);
-				break;
 			case CLOSURE_BSDF_ASHIKHMIN_SHIRLEY_ID:
+			case CLOSURE_BSDF_ASHIKHMIN_SHIRLEY_ANISO_ID:
 				eval = bsdf_ashikhmin_shirley_eval_reflect(sc, sd->I, omega_in, pdf);
 				break;
 #endif
@@ -253,18 +251,18 @@ ccl_device float3 bsdf_eval(KernelGlobals *kg, const ShaderData *sd, const Shade
 				eval = bsdf_transparent_eval_transmit(sc, sd->I, omega_in, pdf);
 				break;
 			case CLOSURE_BSDF_MICROFACET_GGX_ID:
+			case CLOSURE_BSDF_MICROFACET_GGX_ANISO_ID:
 			case CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID:
 				eval = bsdf_microfacet_ggx_eval_transmit(sc, sd->I, omega_in, pdf);
 				break;
 			case CLOSURE_BSDF_MICROFACET_BECKMANN_ID:
+			case CLOSURE_BSDF_MICROFACET_BECKMANN_ANISO_ID:
 			case CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID:
 				eval = bsdf_microfacet_beckmann_eval_transmit(sc, sd->I, omega_in, pdf);
 				break;
 #ifdef __ANISOTROPIC__
-			case CLOSURE_BSDF_WARD_ID:
-				eval = bsdf_ward_eval_transmit(sc, sd->I, omega_in, pdf);
-				break;
 			case CLOSURE_BSDF_ASHIKHMIN_SHIRLEY_ID:
+			case CLOSURE_BSDF_ASHIKHMIN_SHIRLEY_ANISO_ID:
 				eval = bsdf_ashikhmin_shirley_eval_transmit(sc, sd->I, omega_in, pdf);
 				break;
 #endif
@@ -341,18 +339,18 @@ ccl_device void bsdf_blur(KernelGlobals *kg, ShaderClosure *sc, float roughness)
 			bsdf_transparent_blur(sc, roughness);
 			break;
 		case CLOSURE_BSDF_MICROFACET_GGX_ID:
+		case CLOSURE_BSDF_MICROFACET_GGX_ANISO_ID:
 		case CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID:
 			bsdf_microfacet_ggx_blur(sc, roughness);
 			break;
 		case CLOSURE_BSDF_MICROFACET_BECKMANN_ID:
+		case CLOSURE_BSDF_MICROFACET_BECKMANN_ANISO_ID:
 		case CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID:
 			bsdf_microfacet_beckmann_blur(sc, roughness);
 			break;
 #ifdef __ANISOTROPIC__
-		case CLOSURE_BSDF_WARD_ID:
-			bsdf_ward_blur(sc, roughness);
-			break;
 		case CLOSURE_BSDF_ASHIKHMIN_SHIRLEY_ID:
+		case CLOSURE_BSDF_ASHIKHMIN_SHIRLEY_ANISO_ID:
 			bsdf_ashikhmin_shirley_blur(sc, roughness);
 			break;
 #endif
diff --git a/intern/cycles/kernel/closure/bsdf_ashikhmin_shirley.h b/intern/cycles/kernel/closure/bsdf_ashikhmin_shirley.h
index ea5b610ae56..6a5d0410e01 100644
--- a/intern/cycles/kernel/closure/bsdf_ashikhmin_shirley.h
+++ b/intern/cycles/kernel/closure/bsdf_ashikhmin_shirley.h
@@ -31,16 +31,28 @@ Other than that, the implementation directly follows the paper.
 
 CCL_NAMESPACE_BEGIN
 
-
 ccl_device int bsdf_ashikhmin_shirley_setup(ShaderClosure *sc)
 {
-	sc->data0 = clamp(sc->data0, 1e-4f, 1.0f); /* store roughness. could already convert to exponent to save some cycles in eval, */
-	sc->data1 = clamp(sc->data1, 1e-4f, 1.0f); /* but this is more consistent with other bsdfs and shader_blur. */
+	/* store roughness. could already convert to exponent to save some cycles
+	 * in eval, but this is more consistent with other bsdfs and shader_blur. */
+	sc->data0 = clamp(sc->data0, 1e-4f, 1.0f);
+	sc->data1 = sc->data0;
 
 	sc->type = CLOSURE_BSDF_ASHIKHMIN_SHIRLEY_ID;
 	return SD_BSDF | SD_BSDF_HAS_EVAL | SD_BSDF_GLOSSY;
 }
 
+ccl_device int bsdf_ashikhmin_shirley_aniso_setup(ShaderClosure *sc)
+{
+	/* store roughness. could already convert to exponent to save some cycles
+	 * in eval, but this is more consistent with other bsdfs and shader_blur. */
+	sc->data0 = clamp(sc->data0, 1e-4f, 1.0f);
+	sc->data1 = clamp(sc->data1, 1e-4f, 1.0f);
+
+	sc->type = CLOSURE_BSDF_ASHIKHMIN_SHIRLEY_ANISO_ID;
+	return SD_BSDF | SD_BSDF_HAS_EVAL | SD_BSDF_GLOSSY;
+}
+
 ccl_device void bsdf_ashikhmin_shirley_blur(ShaderClosure *sc, float roughness)
 {
 	sc->data0 = fmaxf(roughness, sc->data0); /* clamp roughness */
@@ -55,7 +67,6 @@ ccl_device_inline float bsdf_ashikhmin_shirley_roughness_to_exponent(float rough
 ccl_device float3 bsdf_ashikhmin_shirley_eval_reflect(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
 {
 	float3 N = sc->N;
-	float3 T = sc->T;
 
 	float NdotI = dot(N, I);           /* in Cycles/OSL convention I is omega_out    */
 	float NdotO = dot(N, omega_in);    /* and consequently we use for O omaga_in ;)  */
@@ -85,7 +96,7 @@ ccl_device float3 bsdf_ashikhmin_shirley_eval_reflect(const ShaderClosure *sc, c
 		}
 		else {             /* => ANisotropic case */
 			float3 X, Y;
-			make_orthonormals_tangent(N, T, &X, &Y);
+			make_orthonormals_tangent(N, sc->T, &X, &Y);
 
 			float HdotX = dot(H, X);
 			float HdotY = dot(H, Y);
@@ -117,7 +128,6 @@ ccl_device_inline void bsdf_ashikhmin_shirley_sample_first_quadrant(float n_x, f
 ccl_device int bsdf_ashikhmin_shirley_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)
 {
 	float3 N = sc->N;
-	float3 T = sc->T;
 
 	float NdotI = dot(N, I);
 	if (NdotI > 0.0f) {
@@ -127,7 +137,11 @@ ccl_device int bsdf_ashikhmin_shirley_sample(const ShaderClosure *sc, float3 Ng,
 
 		/* get x,y basis on the surface for anisotropy */
 		float3 X, Y;
-		make_orthonormals_tangent(N, T, &X, &Y);
+
+		if(n_x == n_y)
+			make_orthonormals(N, &X, &Y);
+		else
+			make_orthonormals_tangent(N, sc->T, &X, &Y);
 
 		/* sample spherical coords for h in tangent space */
 		float phi;
diff --git a/intern/cycles/kernel/closure/bsdf_microfacet.h b/intern/cycles/kernel/closure/bsdf_microfacet.h
index b9b682c650f..4a3d223d765 100644
--- a/intern/cycles/kernel/closure/bsdf_microfacet.h
+++ b/intern/cycles/kernel/closure/bsdf_microfacet.h
@@ -365,7 +365,7 @@ ccl_device int bsdf_microfacet_ggx_aniso_setup(ShaderClosure *sc)
 	sc->data0 = clamp(sc->data0, 0.0f, 1.0f); /* alpha_x */
 	sc->data1 = clamp(sc->data1, 0.0f, 1.0f); /* alpha_y */
 	
-	sc->type = CLOSURE_BSDF_MICROFACET_GGX_ID;
+	sc->type = CLOSURE_BSDF_MICROFACET_GGX_ANISO_ID;
 
 	return SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_GLOSSY;
 }
@@ -713,7 +713,7 @@ ccl_device int bsdf_microfacet_beckmann_aniso_setup(ShaderClosure *sc)
 	sc->data0 = clamp(sc->data0, 0.0f, 1.0f); /* alpha_x */
 	sc->data1 = clamp(sc->data1, 0.0f, 1.0f); /* alpha_y */
 
-	sc->type = CLOSURE_BSDF_MICROFACET_BECKMANN_ID;
+	sc->type = CLOSURE_BSDF_MICROFACET_BECKMANN_ANISO_ID;
 	return SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_GLOSSY;
 }
 
diff --git a/intern/cycles/kernel/closure/bsdf_ward.h b/intern/cycles/kernel/closure/bsdf_ward.h
deleted file mode 100644
index c9de615a011..00000000000
--- a/intern/cycles/kernel/closure/bsdf_ward.h
+++ /dev/null
@@ -1,189 +0,0 @@
-/*
- * 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_WARD_H__
-#define __BSDF_WARD_H__
-
-CCL_NAMESPACE_BEGIN
-
-/* WARD */
-
-ccl_device int bsdf_ward_setup(ShaderClosure *sc)
-{
-	sc->data0 = clamp(sc->data0, 1e-4f, 1.0f); /* m_ax */
-	sc->data1 = clamp(sc->data1, 1e-4f, 1.0f); /* m_ay */
-
-	sc->type = CLOSURE_BSDF_WARD_ID;
-	return SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_GLOSSY;
-}
-
-ccl_device void bsdf_ward_blur(ShaderClosure *sc, float roughness)
-{
-	sc->data0 = fmaxf(roughness, sc->data0); /* m_ax */
-	sc->data1 = fmaxf(roughness, sc->data1); /* m_ay */
-}
-
-ccl_device float3 bsdf_ward_eval_reflect(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
-{
-	float m_ax = sc->data0;
-	float m_ay = sc->data1;
-	float3 N = sc->N;
-	float3 T = sc->T;
-
-	float cosNO = dot(N, I);
-	float cosNI = dot(N, omega_in);
-
-	if(cosNI > 0.0f && cosNO > 0.0f) {
-		cosNO = max(cosNO, 1e-4f);
-		cosNI = max(cosNI, 1e-4f);
-
-		// get half vector and get x,y basis on the surface for anisotropy
-		float3 H = normalize(omega_in + I); // normalize needed for pdf
-		float3 X, Y;
-		make_orthonormals_tangent(N, T, &X, &Y);
-		// eq. 4
-		float dotx = dot(H, X) / m_ax;
-		float doty = dot(H, Y) / m_ay;
-		float dotn = dot(H, N);
-		float exp_arg = (dotx * dotx + doty * doty) / (dotn * dotn);
-		float denom = (M_4PI_F * m_ax * m_ay * sqrtf(cosNO * cosNI));
-		float exp_val = expf(-exp_arg);
-		float out = cosNI * exp_val / denom;
-		float oh = dot(H, I);
-		denom = M_4PI_F * m_ax * m_ay * oh * dotn * dotn * dotn;
-		*pdf = exp_val / denom;
-		return make_float3 (out, out, out);
-	}
-
-	return make_float3 (0, 0, 0);
-}
-
-ccl_device float3 bsdf_ward_eval_transmit(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
-{
-	return make_float3(0.0f, 0.0f, 0.0f);
-}
-
-ccl_device int bsdf_ward_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)
-{
-	float m_ax = sc->data0;
-	float m_ay = sc->data1;
-	float3 N = sc->N;
-	float3 T = sc->T;
-
-	float cosNO = dot(N, I);
-	if(cosNO > 0.0f) {
-		// get x,y basis on the surface for anisotropy
-		float3 X, Y;
-		make_orthonormals_tangent(N, T, &X, &Y);
-		// generate random angles for the half vector
-		// eq. 7 (taking care around discontinuities to keep
-		//ttoutput angle in the right quadrant)
-		// we take advantage of cos(atan(x)) == 1/sqrt(1+x^2)
-		//tttt  and sin(atan(x)) == x/sqrt(1+x^2)
-		float alphaRatio = m_ay / m_ax;
-		float cosPhi, sinPhi;
-		if(randu < 0.25f) {
-			float val = 4 * randu;
-			float tanPhi = alphaRatio * tanf(M_PI_2_F * val);
-			cosPhi = 1 / sqrtf(1 + tanPhi * tanPhi);
-			sinPhi = tanPhi * cosPhi;
-		}
-		else if(randu < 0.5f) {
-			float val = 1 - 4 * (0.5f - randu);
-			float tanPhi = alphaRatio * tanf(M_PI_2_F * val);
-			// phi = M_PI_F - phi;
-			cosPhi = -1 / sqrtf(1 + tanPhi * tanPhi);
-			sinPhi = -tanPhi * cosPhi;
-		}
-		else if(randu < 0.75f) {
-			float val = 4 * (randu - 0.5f);
-			float tanPhi = alphaRatio * tanf(M_PI_2_F * val);
-			//phi = M_PI_F + phi;
-			cosPhi = -1 / sqrtf(1 + tanPhi * tanPhi);
-			sinPhi = tanPhi * cosPhi;
-		}
-		else {
-			float val = 1 - 4 * (1 - randu);
-			float tanPhi = alphaRatio * tanf(M_PI_2_F * val);
-			// phi = M_2PI_F - phi;
-			cosPhi = 1 / sqrtf(1 + tanPhi * tanPhi);
-			sinPhi = -tanPhi * cosPhi;
-		}
-		// eq. 6
-		// we take advantage of cos(atan(x)) == 1/sqrt(1+x^2)
-		//tttt  and sin(atan(x)) == x/sqrt(1+x^2)
-		float thetaDenom = (cosPhi * cosPhi) / (m_ax * m_ax) + (sinPhi * sinPhi) / (m_ay * m_ay);
-		float tanTheta2 = -logf(1 - randv) / thetaDenom;
-		float cosTheta  = 1 / sqrtf(1 + tanTheta2);
-		float sinTheta  = cosTheta * sqrtf(tanTheta2);
-
-		float3 h; // already normalized becaused expressed from spherical coordinates
-		h.x = sinTheta * cosPhi;
-		h.y = sinTheta * sinPhi;
-		h.z = cosTheta;
-		// compute terms that are easier in local space
-		float dotx = h.x / m_ax;
-		float doty = h.y / m_ay;
-		float dotn = h.z;
-		// transform to world space
-		h = h.x * X + h.y * Y + h.z * N;
-		// generate the final sample
-		float oh = dot(h, I);
-		*omega_in = 2.0f * oh * h - I;
-		if(dot(Ng, *omega_in) > 0) {
-			float cosNI = dot(N, *omega_in);
-			if(cosNI > 0) {
-				cosNO = max(cosNO, 1e-4f);
-				cosNI = max(cosNI, 1e-4f);
-
-				// eq. 9
-				float exp_arg = (dotx * dotx + doty * doty) / (dotn * dotn);
-				float denom = M_4PI_F * m_ax * m_ay * oh * dotn * dotn * dotn;
-				*pdf = expf(-exp_arg) / denom;
-				// compiler will reuse expressions already computed
-				denom = (M_4PI_F * m_ax * m_ay * sqrtf(cosNO * cosNI));
-				float power = cosNI * expf(-exp_arg) / denom;
-				*eval = make_float3(power, power, power);
-#ifdef __RAY_DIFFERENTIALS__
-				*domega_in_dx = (2 * dot(N, dIdx)) * N - dIdx;
-				*domega_in_dy = (2 * dot(N, dIdy)) * N - dIdy;
-#endif
-			}
-		}
-	}
-	return LABEL_REFLECT|LABEL_GLOSSY;
-}
-
-CCL_NAMESPACE_END
-
-#endif /* __BSDF_WARD_H__ */
-