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diff --git a/intern/cycles/kernel/closure/bsdf_microfacet_multi.h b/intern/cycles/kernel/closure/bsdf_microfacet_multi.h
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+/*
+ * Copyright 2011-2016 Blender Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+CCL_NAMESPACE_BEGIN
+
+/* Most of the code is based on the supplemental implementations from https://eheitzresearch.wordpress.com/240-2/. */
+
+/* === GGX Microfacet distribution functions === */
+
+/* Isotropic GGX microfacet distribution */
+ccl_device_inline float D_ggx(float3 wm, float alpha)
+{
+	wm.z *= wm.z;
+	alpha *= alpha;
+	float tmp = (1.0f - wm.z) + alpha * wm.z;
+	return alpha / max(M_PI_F * tmp*tmp, 1e-7f);
+}
+
+/* Anisotropic GGX microfacet distribution */
+ccl_device_inline float D_ggx_aniso(const float3 wm, const float2 alpha)
+{
+	float slope_x = -wm.x/alpha.x;
+	float slope_y = -wm.y/alpha.y;
+	float tmp = wm.z*wm.z + slope_x*slope_x + slope_y*slope_y;
+
+	return 1.0f / max(M_PI_F * tmp*tmp * alpha.x*alpha.y, 1e-7f);
+}
+
+/* Sample slope distribution (based on page 14 of the supplemental implementation). */
+ccl_device_inline float2 mf_sampleP22_11(const float cosI, const float2 randU)
+{
+	if(cosI > 0.9999f) {
+		const float r = sqrtf(randU.x / (1.0f - randU.x));
+		const float phi = M_2PI_F * randU.y;
+		return make_float2(r*cosf(phi), r*sinf(phi));
+	}
+
+	const float sinI = sqrtf(1.0f - cosI*cosI);
+	const float tanI = sinI/cosI;
+	const float projA = 0.5f * (cosI + 1.0f);
+	if(projA < 0.0001f)
+		return make_float2(0.0f, 0.0f);
+	const float A = 2.0f*randU.x*projA / cosI - 1.0f;
+	float tmp = A*A-1.0f;
+	if(fabsf(tmp) < 1e-7f)
+		return make_float2(0.0f, 0.0f);
+	tmp = 1.0f / tmp;
+	const float D = safe_sqrtf(tanI*tanI*tmp*tmp - (A*A-tanI*tanI)*tmp);
+
+	const float slopeX2 = tanI*tmp + D;
+	const float slopeX = (A < 0.0f || slopeX2 > 1.0f/tanI)? (tanI*tmp - D) : slopeX2;
+
+	float U2;
+	if(randU.y >= 0.5f)
+		U2 = 2.0f*(randU.y - 0.5f);
+	else
+		U2 = 2.0f*(0.5f - randU.y);
+	const float z = (U2*(U2*(U2*0.27385f-0.73369f)+0.46341f)) / (U2*(U2*(U2*0.093073f+0.309420f)-1.0f)+0.597999f);
+	const float slopeY = z * sqrtf(1.0f + slopeX*slopeX);
+
+	if(randU.y >= 0.5f)
+		return make_float2(slopeX, slopeY);
+	else
+		return make_float2(slopeX, -slopeY);
+}
+
+/* Visible normal sampling for the GGX distribution (based on page 7 of the supplemental implementation). */
+ccl_device_inline float3 mf_sample_vndf(const float3 wi, const float2 alpha, const float2 randU)
+{
+	const float3 wi_11 = normalize(make_float3(alpha.x*wi.x, alpha.y*wi.y, wi.z));
+	const float2 slope_11 = mf_sampleP22_11(wi_11.z, randU);
+
+	const float2 cossin_phi = normalize(make_float2(wi_11.x, wi_11.y));
+	const float slope_x = alpha.x*(cossin_phi.x * slope_11.x - cossin_phi.y * slope_11.y);
+	const float slope_y = alpha.y*(cossin_phi.y * slope_11.x + cossin_phi.x * slope_11.y);
+
+	kernel_assert(isfinite(slope_x));
+	return normalize(make_float3(-slope_x, -slope_y, 1.0f));
+}
+
+/* === Phase functions: Glossy, Diffuse and Glass === */
+
+/* Phase function for reflective materials, either without a fresnel term (for compatibility) or with the conductive fresnel term. */
+ccl_device_inline float3 mf_sample_phase_glossy(const float3 wi, float3 *n, float3 *k, float3 *weight, const float3 wm)
+{
+	if(n && k)
+		*weight *= fresnel_conductor(dot(wi, wm), *n, *k);
+
+	return -wi + 2.0f * wm * dot(wi, wm);
+}
+
+ccl_device_inline float3 mf_eval_phase_glossy(const float3 w, const float lambda, const float3 wo, const float2 alpha, float3 *n, float3 *k)
+{
+	if(w.z > 0.9999f)
+		return make_float3(0.0f, 0.0f, 0.0f);
+
+	const float3 wh = normalize(wo - w);
+	if(wh.z < 0.0f)
+		return make_float3(0.0f, 0.0f, 0.0f);
+
+	float pArea = (w.z < -0.9999f)? 1.0f: lambda*w.z;
+
+	const float dotW_WH = dot(-w, wh);
+	if(dotW_WH < 0.0f)
+		return make_float3(0.0f, 0.0f, 0.0f);
+
+	float phase = max(0.0f, dotW_WH) * 0.25f / (pArea * dotW_WH);
+	if(alpha.x == alpha.y)
+		phase *= D_ggx(wh, alpha.x);
+	else
+		phase *= D_ggx_aniso(wh, alpha);
+
+	if(n && k) {
+		/* Apply conductive fresnel term. */
+		return phase * fresnel_conductor(dotW_WH, *n, *k);
+	}
+
+	return make_float3(phase, phase, phase);
+}
+
+/* Phase function for rough lambertian diffuse surfaces. */
+ccl_device_inline float3 mf_sample_phase_diffuse(const float3 wm, const float randu, const float randv)
+{
+	float3 tm, bm;
+	make_orthonormals(wm, &tm, &bm);
+
+	float2 disk = concentric_sample_disk(randu, randv);
+	return disk.x*tm + disk.y*bm + safe_sqrtf(1.0f - disk.x*disk.x - disk.y*disk.y)*wm;
+}
+
+ccl_device_inline float3 mf_eval_phase_diffuse(const float3 w, const float3 wm)
+{
+	const float v = max(0.0f, dot(w, wm)) * M_1_PI_F;
+	return make_float3(v, v, v);
+}
+
+/* Phase function for dielectric transmissive materials, including both reflection and refraction according to the dielectric fresnel term. */
+ccl_device_inline float3 mf_sample_phase_glass(const float3 wi, const float eta, const float3 wm, const float randV, bool *outside)
+{
+	float cosI = dot(wi, wm);
+	float f = fresnel_dielectric_cos(cosI, eta);
+	if(randV < f) {
+		*outside = true;
+		return -wi + 2.0f * wm * cosI;
+	}
+	*outside = false;
+	float inv_eta = 1.0f/eta;
+	float cosT = -safe_sqrtf(1.0f - (1.0f - cosI*cosI) * inv_eta*inv_eta);
+	return normalize(wm*(cosI*inv_eta + cosT) - wi*inv_eta);
+}
+
+ccl_device_inline float3 mf_eval_phase_glass(const float3 w, const float lambda, const float3 wo, const bool wo_outside, const float2 alpha, const float eta)
+{
+	if(w.z > 0.9999f)
+		return make_float3(0.0f, 0.0f, 0.0f);
+
+	float pArea = (w.z < -0.9999f)? 1.0f: lambda*w.z;
+	float v;
+	if(wo_outside) {
+		const float3 wh = normalize(wo - w);
+		if(wh.z < 0.0f)
+			return make_float3(0.0f, 0.0f, 0.0f);
+
+		const float dotW_WH = dot(-w, wh);
+		v = fresnel_dielectric_cos(dotW_WH, eta) * max(0.0f, dotW_WH) * D_ggx(wh, alpha.x) * 0.25f / (pArea * dotW_WH);
+	}
+	else {
+		float3 wh = normalize(wo*eta - w);
+		if(wh.z < 0.0f)
+			wh = -wh;
+		const float dotW_WH = dot(-w, wh), dotWO_WH = dot(wo, wh);
+		if(dotW_WH < 0.0f)
+			return make_float3(0.0f, 0.0f, 0.0f);
+
+		float temp = dotW_WH + eta*dotWO_WH;
+		v = (1.0f - fresnel_dielectric_cos(dotW_WH, eta)) * max(0.0f, dotW_WH) * max(0.0f, -dotWO_WH) * D_ggx(wh, alpha.x) / (pArea * temp * temp);
+	}
+
+	return make_float3(v, v, v);
+}
+
+/* === Utility functions for the random walks === */
+
+/* Smith Lambda function for GGX (based on page 12 of the supplemental implementation). */
+ccl_device_inline float mf_lambda(const float3 w, const float2 alpha)
+{
+	if(w.z > 0.9999f)
+		return 0.0f;
+	else if(w.z < -0.9999f)
+		return -1.0f;
+
+	const float inv_wz2 = 1.0f / (w.z*w.z);
+	const float2 wa = make_float2(w.x, w.y)*alpha;
+	float v = sqrtf(1.0f + dot(wa, wa) * inv_wz2);
+	if(w.z <= 0.0f)
+		v = -v;
+
+	return 0.5f*(v - 1.0f);
+}
+
+/* Height distribution CDF (based on page 4 of the supplemental implementation). */
+ccl_device_inline float mf_invC1(const float h)
+{
+	return 2.0f * saturate(h) - 1.0f;
+}
+
+ccl_device_inline float mf_C1(const float h)
+{
+	return saturate(0.5f * (h + 1.0f));
+}
+
+/* Masking function (based on page 16 of the supplemental implementation). */
+ccl_device_inline float mf_G1(const float3 w, const float C1, const float lambda)
+{
+	if(w.z > 0.9999f)
+		return 1.0f;
+	if(w.z < 1e-5f)
+		return 0.0f;
+	return powf(C1, lambda);
+}
+
+/* Sampling from the visible height distribution (based on page 17 of the supplemental implementation). */
+ccl_device_inline bool mf_sample_height(const float3 w, float *h, float *C1, float *G1, float *lambda, const float U)
+{
+	if(w.z > 0.9999f)
+		return false;
+	if(w.z < -0.9999f) {
+		*C1 *= U;
+		*h = mf_invC1(*C1);
+		*G1 = mf_G1(w, *C1, *lambda);
+	}
+	else if(fabsf(w.z) >= 0.0001f) {
+		if(U > 1.0f - *G1)
+			return false;
+		if(*lambda >= 0.0f) {
+			*C1 = 1.0f;
+		}
+		else {
+			*C1 *= powf(1.0f-U, -1.0f / *lambda);
+		}
+		*h = mf_invC1(*C1);
+		*G1 = mf_G1(w, *C1, *lambda);
+	}
+	return true;
+}
+
+/* === PDF approximations for the different phase functions. ===
+ * As explained in bsdf_microfacet_multi_impl.h, using approximations with MIS still produces an unbiased result. */
+
+/* Approximation for the albedo of the single-scattering GGX distribution,
+ * the missing energy is then approximated as a diffuse reflection for the PDF. */
+ccl_device_inline float mf_ggx_albedo(float r)
+{
+	float albedo = 0.806495f*expf(-1.98712f*r*r) + 0.199531f;
+	albedo -= ((((((1.76741f*r - 8.43891f)*r + 15.784f)*r - 14.398f)*r + 6.45221f)*r - 1.19722f)*r + 0.027803f)*r + 0.00568739f;
+	return saturate(albedo);
+}
+
+ccl_device_inline float mf_ggx_pdf(const float3 wi, const float3 wo, const float alpha)
+{
+	return 0.25f * D_ggx(normalize(wi+wo), alpha) / ((1.0f + mf_lambda(wi, make_float2(alpha, alpha))) * wi.z) + (1.0f - mf_ggx_albedo(alpha)) * wo.z;
+}
+
+ccl_device_inline float mf_ggx_aniso_pdf(const float3 wi, const float3 wo, const float2 alpha)
+{
+	return 0.25f * D_ggx_aniso(normalize(wi+wo), alpha) / ((1.0f + mf_lambda(wi, alpha)) * wi.z) + (1.0f - mf_ggx_albedo(sqrtf(alpha.x*alpha.y))) * wo.z;
+}
+
+ccl_device_inline float mf_diffuse_pdf(const float3 wo)
+{
+	return M_1_PI_F * wo.z;
+}
+
+ccl_device_inline float mf_glass_pdf(const float3 wi, const float3 wo, const float alpha, const float eta)
+{
+	float3 wh;
+	float fresnel;
+	if(wi.z*wo.z > 0.0f) {
+		wh = normalize(wi + wo);
+		fresnel = fresnel_dielectric_cos(dot(wi, wh), eta);
+	}
+	else {
+		wh = normalize(wi + wo*eta);
+		fresnel = 1.0f - fresnel_dielectric_cos(dot(wi, wh), eta);
+	}
+	if(wh.z < 0.0f)
+		wh = -wh;
+	float3 r_wi = (wi.z < 0.0f)? -wi: wi;
+	return fresnel * max(0.0f, dot(r_wi, wh)) * D_ggx(wh, alpha) / ((1.0f + mf_lambda(r_wi, make_float2(alpha, alpha))) * r_wi.z) + fabsf(wo.z);
+}
+
+/* === Actual random walk implementations, one version of mf_eval and mf_sample per phase function. === */
+
+#define MF_NAME_JOIN(x,y) x ## _ ## y
+#define MF_NAME_EVAL(x,y) MF_NAME_JOIN(x,y)
+#define MF_FUNCTION_FULL_NAME(prefix) MF_NAME_EVAL(prefix, MF_PHASE_FUNCTION)
+
+#define MF_PHASE_FUNCTION glass
+#define MF_MULTI_GLASS
+#include "bsdf_microfacet_multi_impl.h"
+
+/* The diffuse phase function is not implemented as a node yet. */
+#if 0
+#define MF_PHASE_FUNCTION diffuse
+#define MF_MULTI_DIFFUSE
+#include "bsdf_microfacet_multi_impl.h"
+#endif
+
+#define MF_PHASE_FUNCTION glossy
+#define MF_MULTI_GLOSSY
+#include "bsdf_microfacet_multi_impl.h"
+
+ccl_device void bsdf_microfacet_multi_ggx_blur(ShaderClosure *sc, float roughness)
+{
+	sc->data0 = fmaxf(roughness, sc->data0); /* alpha_x */
+	sc->data1 = fmaxf(roughness, sc->data1); /* alpha_y */
+}
+
+/* === Closure implementations === */
+
+/* Multiscattering GGX Glossy closure */
+
+ccl_device int bsdf_microfacet_multi_ggx_common_setup(ShaderClosure *sc)
+{
+	sc->data0 = clamp(sc->data0, 1e-4f, 1.0f); /* alpha */
+	sc->data1 = clamp(sc->data1, 1e-4f, 1.0f);
+	sc->custom1 = saturate(sc->custom1); /* color */
+	sc->custom2 = saturate(sc->custom2);
+	sc->custom3 = saturate(sc->custom3);
+
+	sc->type = CLOSURE_BSDF_MICROFACET_MULTI_GGX_ID;
+
+	return SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_NEEDS_LCG|SD_BSDF_HAS_CUSTOM;
+}
+
+ccl_device int bsdf_microfacet_multi_ggx_aniso_setup(ShaderClosure *sc)
+{
+	if(sc->T == make_float3(0.0f, 0.0f, 0.0f))
+		sc->T = make_float3(1.0f, 0.0f, 0.0f);
+
+	return bsdf_microfacet_multi_ggx_common_setup(sc);
+}
+
+ccl_device int bsdf_microfacet_multi_ggx_setup(ShaderClosure *sc)
+{
+	sc->data1 = sc->data0;
+
+	return bsdf_microfacet_multi_ggx_common_setup(sc);
+}
+
+ccl_device float3 bsdf_microfacet_multi_ggx_eval_transmit(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf, uint *lcg_state) {
+	*pdf = 0.0f;
+	return make_float3(0.0f, 0.0f, 0.0f);
+}
+
+ccl_device float3 bsdf_microfacet_multi_ggx_eval_reflect(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf, uint *lcg_state) {
+	bool is_aniso = (sc->data0 != sc->data1);
+	float3 X, Y, Z;
+	Z = sc->N;
+	if(is_aniso)
+		make_orthonormals_tangent(Z, sc->T, &X, &Y);
+	else
+		make_orthonormals(Z, &X, &Y);
+
+	float3 localI = make_float3(dot(I, X), dot(I, Y), dot(I, Z));
+	float3 localO = make_float3(dot(omega_in, X), dot(omega_in, Y), dot(omega_in, Z));
+
+	if(is_aniso)
+		*pdf = mf_ggx_aniso_pdf(localI, localO, make_float2(sc->data0, sc->data1));
+	else
+		*pdf = mf_ggx_pdf(localI, localO, sc->data0);
+	return mf_eval_glossy(localI, localO, true, make_float3(sc->custom1, sc->custom2, sc->custom3), sc->data0, sc->data1, lcg_state, NULL, NULL);
+}
+
+ccl_device int bsdf_microfacet_multi_ggx_sample(KernelGlobals *kg, 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, uint *lcg_state)
+{
+	bool is_aniso = (sc->data0 != sc->data1);
+	float3 X, Y, Z;
+	Z = sc->N;
+	if(is_aniso)
+		make_orthonormals_tangent(Z, sc->T, &X, &Y);
+	else
+		make_orthonormals(Z, &X, &Y);
+
+	float3 localI = make_float3(dot(I, X), dot(I, Y), dot(I, Z));
+	float3 localO;
+
+	*eval = mf_sample_glossy(localI, &localO, make_float3(sc->custom1, sc->custom2, sc->custom3), sc->data0, sc->data1, lcg_state, NULL, NULL);
+	if(is_aniso)
+		*pdf = mf_ggx_aniso_pdf(localI, localO, make_float2(sc->data0, sc->data1));
+	else
+		*pdf = mf_ggx_pdf(localI, localO, sc->data0);
+	*eval *= *pdf;
+
+	*omega_in = X*localO.x + Y*localO.y + Z*localO.z;
+	return LABEL_REFLECT|LABEL_GLOSSY;
+}
+
+/* Multiscattering GGX Glass closure */
+
+ccl_device int bsdf_microfacet_multi_ggx_glass_setup(ShaderClosure *sc)
+{
+	sc->data0 = clamp(sc->data0, 1e-4f, 1.0f); /* alpha */
+	sc->data1 = sc->data0;
+	sc->data2 = max(0.0f, sc->data2); /* ior */
+	sc->custom1 = saturate(sc->custom1); /* color */
+	sc->custom2 = saturate(sc->custom2);
+	sc->custom3 = saturate(sc->custom3);
+
+	sc->type = CLOSURE_BSDF_MICROFACET_MULTI_GGX_GLASS_ID;
+
+	return SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_NEEDS_LCG|SD_BSDF_HAS_CUSTOM;
+}
+
+ccl_device float3 bsdf_microfacet_multi_ggx_glass_eval_transmit(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf, uint *lcg_state) {
+	float3 X, Y, Z;
+	Z = sc->N;
+	make_orthonormals(Z, &X, &Y);
+
+	float3 localI = make_float3(dot(I, X), dot(I, Y), dot(I, Z));
+	float3 localO = make_float3(dot(omega_in, X), dot(omega_in, Y), dot(omega_in, Z));
+
+	*pdf = mf_glass_pdf(localI, localO, sc->data0, sc->data2);
+	return mf_eval_glass(localI, localO, false, make_float3(sc->custom1, sc->custom2, sc->custom3), sc->data0, sc->data1, lcg_state, sc->data2);
+}
+
+ccl_device float3 bsdf_microfacet_multi_ggx_glass_eval_reflect(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf, uint *lcg_state) {
+	float3 X, Y, Z;
+	Z = sc->N;
+	make_orthonormals(Z, &X, &Y);
+
+	float3 localI = make_float3(dot(I, X), dot(I, Y), dot(I, Z));
+	float3 localO = make_float3(dot(omega_in, X), dot(omega_in, Y), dot(omega_in, Z));
+
+	*pdf = mf_glass_pdf(localI, localO, sc->data0, sc->data2);
+	return mf_eval_glass(localI, localO, true, make_float3(sc->custom1, sc->custom2, sc->custom3), sc->data0, sc->data1, lcg_state, sc->data2);
+}
+
+ccl_device int bsdf_microfacet_multi_ggx_glass_sample(KernelGlobals *kg, 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, uint *lcg_state)
+{
+	float3 X, Y, Z;
+	Z = sc->N;
+	make_orthonormals(Z, &X, &Y);
+
+	float3 localI = make_float3(dot(I, X), dot(I, Y), dot(I, Z));
+	float3 localO;
+
+	*eval = mf_sample_glass(localI, &localO, make_float3(sc->custom1, sc->custom2, sc->custom3), sc->data0, sc->data1, lcg_state, sc->data2);
+	*pdf = mf_glass_pdf(localI, localO, sc->data0, sc->data2);
+	*eval *= *pdf;
+
+	*omega_in = X*localO.x + Y*localO.y + Z*localO.z;
+	if(localO.z*localI.z > 0.0f)
+		return LABEL_REFLECT|LABEL_GLOSSY;
+	else
+		return LABEL_TRANSMIT|LABEL_GLOSSY;
+}
+
+CCL_NAMESPACE_END