Differential D17099 Diff 59871 intern/cycles/kernel/closure/bsdf_microfacet.h

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intern/cycles/kernel/closure/bsdf_microfacet.h

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ccl_device_inline void microfacet_beckmann_sample_slopes(KernelGlobals kg,		ccl_device_inline void microfacet_beckmann_sample_slopes(KernelGlobals kg,
const float cos_theta_i,		const float cos_theta_i,
const float sin_theta_i,		const float sin_theta_i,
float randu,		float randu,
float randv,		float randv,
ccl_private float *slope_x,		ccl_private float *slope_x,
ccl_private float *slope_y,		ccl_private float *slope_y,
ccl_private float *G1i)		ccl_private float *lambda_i)
{		{
/* Special case (normal incidence). */		/* Special case (normal incidence). */
if (cos_theta_i >= 0.99999f) {		if (cos_theta_i >= 0.99999f) {
const float r = sqrtf(-logf(randu));		const float r = sqrtf(-logf(randu));
const float phi = M_2PI_F * randv;		const float phi = M_2PI_F * randv;
slope_x = r cosf(phi);		slope_x = r cosf(phi);
slope_y = r sinf(phi);		slope_y = r sinf(phi);
*G1i = 1.0f;		*lambda_i = 0.0f;

return;		return;
}		}

/* Precomputations. */		/* Precomputations. */
const float tan_theta_i = sin_theta_i / cos_theta_i;		const float tan_theta_i = sin_theta_i / cos_theta_i;
const float inv_a = tan_theta_i;		const float inv_a = tan_theta_i;
const float cot_theta_i = 1.0f / tan_theta_i;		const float cot_theta_i = 1.0f / tan_theta_i;
const float erf_a = fast_erff(cot_theta_i);		const float erf_a = fast_erff(cot_theta_i);
const float exp_a2 = expf(-cot_theta_i * cot_theta_i);		const float exp_a2 = expf(-cot_theta_i * cot_theta_i);
const float SQRT_PI_INV = 0.56418958354f;		const float SQRT_PI_INV = 0.56418958354f;
const float Lambda = 0.5f * (erf_a - 1.0f) + (0.5f * SQRT_PI_INV) * (exp_a2 * inv_a);		const float Lambda = 0.5f * (erf_a - 1.0f) + (0.5f * SQRT_PI_INV) * (exp_a2 * inv_a);
const float G1 = 1.0f / (1.0f + Lambda); /* masking */

*G1i = G1;		*lambda_i = Lambda;

/* Based on paper from Wenzel Jakob		/* Based on paper from Wenzel Jakob
* An Improved Visible Normal Sampling Routine for the Beckmann Distribution		* An Improved Visible Normal Sampling Routine for the Beckmann Distribution
*		*
* http://www.mitsuba-renderer.org/~wenzel/files/visnormal.pdf		* http://www.mitsuba-renderer.org/~wenzel/files/visnormal.pdf
*		*
* Reformulation from OpenShadingLanguage which avoids using inverse		* Reformulation from OpenShadingLanguage which avoids using inverse
* trigonometric functions.		* trigonometric functions.
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*/		*/

ccl_device_inline void microfacet_ggx_sample_slopes(const float cos_theta_i,		ccl_device_inline void microfacet_ggx_sample_slopes(const float cos_theta_i,
const float sin_theta_i,		const float sin_theta_i,
float randu,		float randu,
float randv,		float randv,
ccl_private float *slope_x,		ccl_private float *slope_x,
ccl_private float *slope_y,		ccl_private float *slope_y,
ccl_private float *G1i)		ccl_private float *lambda_i)
{		{
/* Special case (normal incidence). */		/* Special case (normal incidence). */
if (cos_theta_i >= 0.99999f) {		if (cos_theta_i >= 0.99999f) {
const float r = sqrtf(randu / (1.0f - randu));		const float r = sqrtf(randu / (1.0f - randu));
const float phi = M_2PI_F * randv;		const float phi = M_2PI_F * randv;
slope_x = r cosf(phi);		slope_x = r cosf(phi);
slope_y = r sinf(phi);		slope_y = r sinf(phi);
*G1i = 1.0f;		*lambda_i = 0.0f;

return;		return;
}		}

/* Precomputations. */		/* Precomputations. */
const float tan_theta_i = sin_theta_i / cos_theta_i;		const float tan_theta_i = sin_theta_i / cos_theta_i;
const float G1_inv = 0.5f * (1.0f + safe_sqrtf(1.0f + tan_theta_i * tan_theta_i));		const float G1_inv = 0.5f * (1.0f + safe_sqrtf(1.0f + tan_theta_i * tan_theta_i));

*G1i = 1.0f / G1_inv;		*lambda_i = G1_inv - 1.0f;

/* Sample slope_x. */		/* Sample slope_x. */
const float A = 2.0f * randu * G1_inv - 1.0f;		const float A = 2.0f * randu * G1_inv - 1.0f;
const float AA = A * A;		const float AA = A * A;
const float tmp = 1.0f / (AA - 1.0f);		const float tmp = 1.0f / (AA - 1.0f);
const float B = tan_theta_i;		const float B = tan_theta_i;
const float BB = B * B;		const float BB = B * B;
const float D = safe_sqrtf(BB * (tmp * tmp) - (AA - BB) * tmp);		const float D = safe_sqrtf(BB * (tmp * tmp) - (AA - BB) * tmp);
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template<MicrofacetType m_type>		template<MicrofacetType m_type>
ccl_device_forceinline float3 microfacet_sample_stretched(KernelGlobals kg,		ccl_device_forceinline float3 microfacet_sample_stretched(KernelGlobals kg,
const float3 wi,		const float3 wi,
const float alpha_x,		const float alpha_x,
const float alpha_y,		const float alpha_y,
const float randu,		const float randu,
const float randv,		const float randv,
ccl_private float *G1i)		ccl_private float *lambda_i)
{		{
/* 1. stretch wi */		/* 1. stretch wi */
float3 wi_ = make_float3(alpha_x * wi.x, alpha_y * wi.y, wi.z);		float3 wi_ = make_float3(alpha_x * wi.x, alpha_y * wi.y, wi.z);
wi_ = normalize(wi_);		wi_ = normalize(wi_);

/* Compute polar coordinates of wi_. */		/* Compute polar coordinates of wi_. */
float costheta_ = 1.0f;		float costheta_ = 1.0f;
float sintheta_ = 0.0f;		float sintheta_ = 0.0f;
Show All 9 Lines	if (wi_.z < 0.99999f) {
sinphi_ = wi_.y * invlen;		sinphi_ = wi_.y * invlen;
}		}

/* 2. sample P22_{wi}(x_slope, y_slope, 1, 1) */		/* 2. sample P22_{wi}(x_slope, y_slope, 1, 1) */
float slope_x, slope_y;		float slope_x, slope_y;

if (m_type == MicrofacetType::BECKMANN) {		if (m_type == MicrofacetType::BECKMANN) {
microfacet_beckmann_sample_slopes(		microfacet_beckmann_sample_slopes(
kg, costheta_, sintheta_, randu, randv, &slope_x, &slope_y, G1i);		kg, costheta_, sintheta_, randu, randv, &slope_x, &slope_y, lambda_i);
}		}
else {		else {
microfacet_ggx_sample_slopes(costheta_, sintheta_, randu, randv, &slope_x, &slope_y, G1i);		microfacet_ggx_sample_slopes(costheta_, sintheta_, randu, randv, &slope_x, &slope_y, lambda_i);
}		}

/* 3. rotate */		/* 3. rotate */
float tmp = cosphi_ * slope_x - sinphi_ * slope_y;		float tmp = cosphi_ * slope_x - sinphi_ * slope_y;
slope_y = sinphi_ * slope_x + cosphi_ * slope_y;		slope_y = sinphi_ * slope_x + cosphi_ * slope_y;
slope_x = tmp;		slope_x = tmp;

/* 4. unstretch */		/* 4. unstretch */
Show All 39 Lines	ccl_device_forceinline float bsdf_clearcoat_D(float alpha2, float cos_NH)
if (alpha2 >= 1.0f) {		if (alpha2 >= 1.0f) {
return M_1_PI_F;		return M_1_PI_F;
}		}

const float t = 1.0f + (alpha2 - 1.0f) * cos_NH * cos_NH;		const float t = 1.0f + (alpha2 - 1.0f) * cos_NH * cos_NH;
return (alpha2 - 1.0f) / (M_PI_F * logf(alpha2) * t);		return (alpha2 - 1.0f) / (M_PI_F * logf(alpha2) * t);
}		}

/* Monodirectional shadowing-masking term. */		/* Smith shadowing-masking term, here in the non-separable form.
		* For details, see:
		* Understanding the Masking-Shadowing Function in Microfacet-Based BRDFs.
		* Eric Heitz, JCGT Vol. 3, No. 2, 2014.
		* https://jcgt.org/published/0003/02/03/ */
template<MicrofacetType m_type>		template<MicrofacetType m_type>
ccl_device_inline float bsdf_G1_from_sqr_alpha_tan_n(float sqr_alpha_tan_n)		ccl_device_inline float bsdf_lambda_from_sqr_alpha_tan_n(float sqr_alpha_tan_n)
{		{
if (m_type == MicrofacetType::GGX) {		if (m_type == MicrofacetType::GGX) {
return 2.0f / (1.0f + sqrtf(1.0f + sqr_alpha_tan_n));		/* Equation 72. */
		return 0.5f * (sqrtf(1.0f + sqr_alpha_tan_n) - 1.0f);
}		}
else {		else {
/* m_type == MicrofacetType::BECKMANN */		/* m_type == MicrofacetType::BECKMANN
		* Approximation from below Equation 69. */
		if (sqr_alpha_tan_n < 0.39f) {
		/* Equivalent to a >= 1.6f, but also handles sqr_alpha_tan_n == 0.0f cleanly. */
		return 0.0f;
		}

const float a = inversesqrtf(sqr_alpha_tan_n);		const float a = inversesqrtf(sqr_alpha_tan_n);
return (a > 1.6f) ? 1.0f : ((2.181f * a + 3.535f) * a) / ((2.577f * a + 2.276f) * a + 1.0f);		return ((0.396f * a - 1.259f) * a + 1.0f) / ((2.181f * a + 3.535f) * a);
}		}
}		}

template<MicrofacetType m_type> ccl_device_inline float bsdf_G1(float alpha2, float cos_N)		template<MicrofacetType m_type> ccl_device_inline float bsdf_lambda(float alpha2, float cos_N)
{		{
return bsdf_G1_from_sqr_alpha_tan_n<m_type>(alpha2 * fmaxf(1.0f / (cos_N * cos_N) - 1.0f, 0.0f));		return bsdf_lambda_from_sqr_alpha_tan_n<m_type>(alpha2 * fmaxf(1.0f / sqr(cos_N) - 1.0f, 0.0f));
}		}

template<MicrofacetType m_type>		template<MicrofacetType m_type>
ccl_device_inline float bsdf_aniso_G1(float alpha_x, float alpha_y, float3 V)		ccl_device_inline float bsdf_aniso_lambda(float alpha_x, float alpha_y, float3 V)
{		{
return bsdf_G1_from_sqr_alpha_tan_n<m_type>((sqr(alpha_x * V.x) + sqr(alpha_y * V.y)) /		const float sqr_alpha_tan_n = (sqr(alpha_x * V.x) + sqr(alpha_y * V.y)) / sqr(V.z);
sqr(V.z));		return bsdf_lambda_from_sqr_alpha_tan_n<m_type>(sqr_alpha_tan_n);
}		}

/* Smith's separable shadowing-masking term. */		/* Combined shadowing-masking term. */
template<MicrofacetType m_type>		template<MicrofacetType m_type>
ccl_device_inline float bsdf_G(float alpha2, float cos_NI, float cos_NO)		ccl_device_inline float bsdf_G(float alpha2, float cos_NI, float cos_NO)
{		{
return bsdf_G1<m_type>(alpha2, cos_NI) * bsdf_G1<m_type>(alpha2, cos_NO);		return 1.0f / (1.0f + bsdf_lambda<m_type>(alpha2, cos_NI) + bsdf_lambda<m_type>(alpha2, cos_NO));
}		}

/* Normal distribution function. */		/* Normal distribution function. */
template<MicrofacetType m_type> ccl_device_inline float bsdf_D(float alpha2, float cos_NH)		template<MicrofacetType m_type> ccl_device_inline float bsdf_D(float alpha2, float cos_NH)
{		{
const float cos_NH2 = sqr(cos_NH);		const float cos_NH2 = sqr(cos_NH);

if (m_type == MicrofacetType::BECKMANN) {		if (m_type == MicrofacetType::BECKMANN) {
▲ Show 20 Lines • Show All 64 Lines • ▼ Show 20 Lines	ccl_device Spectrum bsdf_microfacet_eval(ccl_private const ShaderClosure *sc,
}		}

/* Compute half vector. */		/* Compute half vector. */
float3 H = m_refractive ? -(bsdf->ior * wo + wi) : (wi + wo);		float3 H = m_refractive ? -(bsdf->ior * wo + wi) : (wi + wo);
const float inv_len_H = 1.0f / len(H);		const float inv_len_H = 1.0f / len(H);
H *= inv_len_H;		H *= inv_len_H;

const float cos_NH = dot(N, H);		const float cos_NH = dot(N, H);
float D, G1i, G1o;		float D, lambdaI, lambdaO;

/* TODO: add support for anisotropic transmission. */		/* TODO: add support for anisotropic transmission. */
if (alpha_x == alpha_y \|\| m_refractive) { /* Isotropic. */		if (alpha_x == alpha_y \|\| m_refractive) { /* Isotropic. */
float alpha2 = alpha_x * alpha_y;		float alpha2 = alpha_x * alpha_y;

if (bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_CLEARCOAT_ID) {		if (bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_CLEARCOAT_ID) {
D = bsdf_clearcoat_D(alpha2, cos_NH);		D = bsdf_clearcoat_D(alpha2, cos_NH);

/* The masking-shadowing term for clearcoat has a fixed alpha of 0.25		/* The masking-shadowing term for clearcoat has a fixed alpha of 0.25
* => alpha2 = 0.25 * 0.25 */		* => alpha2 = 0.25 * 0.25 */
alpha2 = 0.0625f;		alpha2 = 0.0625f;
}		}
else {		else {
D = bsdf_D<m_type>(alpha2, cos_NH);		D = bsdf_D<m_type>(alpha2, cos_NH);
}		}

G1i = bsdf_G1<m_type>(alpha2, cos_NI);		lambdaI = bsdf_lambda<m_type>(alpha2, cos_NI);
G1o = bsdf_G1<m_type>(alpha2, cos_NO);		lambdaO = bsdf_lambda<m_type>(alpha2, cos_NO);
}		}
else { /* Anisotropic. */		else { /* Anisotropic. */
float3 X, Y;		float3 X, Y;
make_orthonormals_tangent(N, bsdf->T, &X, &Y);		make_orthonormals_tangent(N, bsdf->T, &X, &Y);

const float3 local_H = make_float3(dot(X, H), dot(Y, H), cos_NH);		const float3 local_H = make_float3(dot(X, H), dot(Y, H), cos_NH);
const float3 local_I = make_float3(dot(X, wi), dot(Y, wi), cos_NI);		const float3 local_I = make_float3(dot(X, wi), dot(Y, wi), cos_NI);
const float3 local_O = make_float3(dot(X, wo), dot(Y, wo), cos_NO);		const float3 local_O = make_float3(dot(X, wo), dot(Y, wo), cos_NO);

D = bsdf_aniso_D<m_type>(alpha_x, alpha_y, local_H);		D = bsdf_aniso_D<m_type>(alpha_x, alpha_y, local_H);

G1i = bsdf_aniso_G1<m_type>(alpha_x, alpha_y, local_I);		lambdaI = bsdf_aniso_lambda<m_type>(alpha_x, alpha_y, local_I);
G1o = bsdf_aniso_G1<m_type>(alpha_x, alpha_y, local_O);		lambdaO = bsdf_aniso_lambda<m_type>(alpha_x, alpha_y, local_O);
}		}

const float common = G1i * D / cos_NI *		const float common = D / cos_NI *
(m_refractive ?		(m_refractive ?
sqr(bsdf->ior * inv_len_H) * fabsf(dot(H, wi) * dot(H, wo)) :		sqr(bsdf->ior * inv_len_H) * fabsf(dot(H, wi) * dot(H, wo)) :
0.25f);		0.25f);

*pdf = common;		*pdf = common / (1.0f + lambdaI);

const Spectrum F = m_refractive ? one_spectrum() : reflection_color(bsdf, wo, H);		const Spectrum F = m_refractive ? one_spectrum() : reflection_color(bsdf, wo, H);

return F * G1o * common;		return F * common / (1.0f + lambdaO + lambdaI);
}		}

template<MicrofacetType m_type>		template<MicrofacetType m_type>
ccl_device int bsdf_microfacet_sample(KernelGlobals kg,		ccl_device int bsdf_microfacet_sample(KernelGlobals kg,
ccl_private const ShaderClosure *sc,		ccl_private const ShaderClosure *sc,
float3 Ng,		float3 Ng,
float3 wi,		float3 wi,
float randu,		float randu,
Show All 24 Lines	if (alpha_x == alpha_y) {
make_orthonormals(N, &X, &Y);		make_orthonormals(N, &X, &Y);
}		}
else {		else {
make_orthonormals_tangent(N, bsdf->T, &X, &Y);		make_orthonormals_tangent(N, bsdf->T, &X, &Y);
}		}

/* Importance sampling with distribution of visible normals. Vectors are transformed to local		/* Importance sampling with distribution of visible normals. Vectors are transformed to local
* space before and after sampling. */		* space before and after sampling. */
float G1i;		float lambdaI;
const float3 local_I = make_float3(dot(X, wi), dot(Y, wi), cos_NI);		const float3 local_I = make_float3(dot(X, wi), dot(Y, wi), cos_NI);
const float3 local_H = microfacet_sample_stretched<m_type>(		const float3 local_H = microfacet_sample_stretched<m_type>(
kg, local_I, alpha_x, alpha_y, randu, randv, &G1i);		kg, local_I, alpha_x, alpha_y, randu, randv, &lambdaI);

const float3 H = X * local_H.x + Y * local_H.y + N * local_H.z;		const float3 H = X * local_H.x + Y * local_H.y + N * local_H.z;
const float cos_NH = local_H.z;		const float cos_NH = local_H.z;
const float cos_HI = dot(H, wi);		const float cos_HI = dot(H, wi);

bool valid = false;		bool valid = false;
if (m_refractive) {		if (m_refractive) {
float3 R, T;		float3 R, T;
Show All 28 Lines	if (alpha_x * alpha_y <= 1e-7f \|\| (m_refractive && fabsf(m_eta - 1.0f) < 1e-4f)) {

if (use_fresnel && !m_refractive) {		if (use_fresnel && !m_refractive) {
eval = reflection_color(bsdf, *wo, H);		eval = reflection_color(bsdf, *wo, H);
}		}
}		}
else {		else {
label \|= LABEL_GLOSSY;		label \|= LABEL_GLOSSY;
float cos_NO = dot(N, *wo);		float cos_NO = dot(N, *wo);
float D, G1o;		float D, lambdaO;

/* TODO: add support for anisotropic transmission. */		/* TODO: add support for anisotropic transmission. */
if (alpha_x == alpha_y \|\| m_refractive) { /* Isotropic. */		if (alpha_x == alpha_y \|\| m_refractive) { /* Isotropic. */
float alpha2 = alpha_x * alpha_y;		float alpha2 = alpha_x * alpha_y;

if (bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_CLEARCOAT_ID) {		if (bsdf->type == CLOSURE_BSDF_MICROFACET_GGX_CLEARCOAT_ID) {
D = bsdf_clearcoat_D(alpha2, cos_NH);		D = bsdf_clearcoat_D(alpha2, cos_NH);

/* The masking-shadowing term for clearcoat has a fixed alpha of 0.25		/* The masking-shadowing term for clearcoat has a fixed alpha of 0.25
* => alpha2 = 0.25 * 0.25 */		* => alpha2 = 0.25 * 0.25 */
alpha2 = 0.0625f;		alpha2 = 0.0625f;

/* Recalculate G1i. */		/* Recalculate lambdaI. */
G1i = bsdf_G1<m_type>(alpha2, cos_NI);		lambdaI = bsdf_lambda<m_type>(alpha2, cos_NI);
}		}
else {		else {
D = bsdf_D<m_type>(alpha2, cos_NH);		D = bsdf_D<m_type>(alpha2, cos_NH);
}		}

G1o = bsdf_G1<m_type>(alpha2, cos_NO);		lambdaO = bsdf_lambda<m_type>(alpha2, cos_NO);
}		}
else { /* Anisotropic. */		else { /* Anisotropic. */
const float3 local_O = make_float3(dot(X, wo), dot(Y, wo), cos_NO);		const float3 local_O = make_float3(dot(X, wo), dot(Y, wo), cos_NO);

D = bsdf_aniso_D<m_type>(alpha_x, alpha_y, local_H);		D = bsdf_aniso_D<m_type>(alpha_x, alpha_y, local_H);

G1o = bsdf_aniso_G1<m_type>(alpha_x, alpha_y, local_O);		lambdaO = bsdf_aniso_lambda<m_type>(alpha_x, alpha_y, local_O);
}		}

const float cos_HO = dot(H, *wo);		const float cos_HO = dot(H, *wo);
const float common = G1i * D / cos_NI *		const float common = D / cos_NI *
(m_refractive ? fabsf(cos_HI * cos_HO) / sqr(cos_HO + cos_HI / m_eta) :		(m_refractive ? fabsf(cos_HI * cos_HO) / sqr(cos_HO + cos_HI / m_eta) :
0.25f);		0.25f);

*pdf = common;		*pdf = common / (1.0f + lambdaI);

Spectrum F = m_refractive ? one_spectrum() : reflection_color(bsdf, *wo, H);		Spectrum F = m_refractive ? one_spectrum() : reflection_color(bsdf, *wo, H);

eval = G1o common * F;		eval = F common / (1.0f + lambdaI + lambdaO);
}		}

*sampled_roughness = make_float2(alpha_x, alpha_y);		*sampled_roughness = make_float2(alpha_x, alpha_y);
*eta = m_refractive ? 1.0f / m_eta : m_eta;		*eta = m_refractive ? 1.0f / m_eta : m_eta;

return label;		return label;
}		}

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