forked from bartvdbraak/blender
314 lines
12 KiB
C
314 lines
12 KiB
C
/*
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* Adapted from Open Shading Language with this license:
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*
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* Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
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* All Rights Reserved.
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*
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* Modifications Copyright 2011, Blender Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of Sony Pictures Imageworks nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef __BSDF_HAIR_H__
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#define __BSDF_HAIR_H__
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CCL_NAMESPACE_BEGIN
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typedef ccl_addr_space struct HairBsdf {
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SHADER_CLOSURE_BASE;
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float3 T;
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float roughness1;
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float roughness2;
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float offset;
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} HairBsdf;
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static_assert(sizeof(ShaderClosure) >= sizeof(HairBsdf), "HairBsdf is too large!");
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ccl_device int bsdf_hair_reflection_setup(HairBsdf *bsdf)
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{
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bsdf->type = CLOSURE_BSDF_HAIR_REFLECTION_ID;
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bsdf->roughness1 = clamp(bsdf->roughness1, 0.001f, 1.0f);
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bsdf->roughness2 = clamp(bsdf->roughness2, 0.001f, 1.0f);
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return SD_BSDF | SD_BSDF_HAS_EVAL;
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}
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ccl_device int bsdf_hair_transmission_setup(HairBsdf *bsdf)
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{
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bsdf->type = CLOSURE_BSDF_HAIR_TRANSMISSION_ID;
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bsdf->roughness1 = clamp(bsdf->roughness1, 0.001f, 1.0f);
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bsdf->roughness2 = clamp(bsdf->roughness2, 0.001f, 1.0f);
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return SD_BSDF | SD_BSDF_HAS_EVAL;
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}
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ccl_device bool bsdf_hair_merge(const ShaderClosure *a, const ShaderClosure *b)
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{
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const HairBsdf *bsdf_a = (const HairBsdf *)a;
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const HairBsdf *bsdf_b = (const HairBsdf *)b;
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return (isequal_float3(bsdf_a->T, bsdf_b->T)) && (bsdf_a->roughness1 == bsdf_b->roughness1) &&
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(bsdf_a->roughness2 == bsdf_b->roughness2) && (bsdf_a->offset == bsdf_b->offset);
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}
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ccl_device float3 bsdf_hair_reflection_eval_reflect(const ShaderClosure *sc,
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const float3 I,
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const float3 omega_in,
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float *pdf)
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{
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const HairBsdf *bsdf = (const HairBsdf *)sc;
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float offset = bsdf->offset;
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float3 Tg = bsdf->T;
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float roughness1 = bsdf->roughness1;
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float roughness2 = bsdf->roughness2;
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float Iz = dot(Tg, I);
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float3 locy = normalize(I - Tg * Iz);
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float theta_r = M_PI_2_F - fast_acosf(Iz);
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float omega_in_z = dot(Tg, omega_in);
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float3 omega_in_y = normalize(omega_in - Tg * omega_in_z);
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float theta_i = M_PI_2_F - fast_acosf(omega_in_z);
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float cosphi_i = dot(omega_in_y, locy);
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if (M_PI_2_F - fabsf(theta_i) < 0.001f || cosphi_i < 0.0f) {
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*pdf = 0.0f;
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return make_float3(*pdf, *pdf, *pdf);
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}
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float roughness1_inv = 1.0f / roughness1;
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float roughness2_inv = 1.0f / roughness2;
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float phi_i = fast_acosf(cosphi_i) * roughness2_inv;
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phi_i = fabsf(phi_i) < M_PI_F ? phi_i : M_PI_F;
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float costheta_i = fast_cosf(theta_i);
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float a_R = fast_atan2f(((M_PI_2_F + theta_r) * 0.5f - offset) * roughness1_inv, 1.0f);
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float b_R = fast_atan2f(((-M_PI_2_F + theta_r) * 0.5f - offset) * roughness1_inv, 1.0f);
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float theta_h = (theta_i + theta_r) * 0.5f;
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float t = theta_h - offset;
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float phi_pdf = fast_cosf(phi_i * 0.5f) * 0.25f * roughness2_inv;
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float theta_pdf = roughness1 /
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(2 * (t * t + roughness1 * roughness1) * (a_R - b_R) * costheta_i);
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*pdf = phi_pdf * theta_pdf;
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return make_float3(*pdf, *pdf, *pdf);
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}
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ccl_device float3 bsdf_hair_transmission_eval_reflect(const ShaderClosure *sc,
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const float3 I,
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const float3 omega_in,
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float *pdf)
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{
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return make_float3(0.0f, 0.0f, 0.0f);
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}
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ccl_device float3 bsdf_hair_reflection_eval_transmit(const ShaderClosure *sc,
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const float3 I,
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const float3 omega_in,
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float *pdf)
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{
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return make_float3(0.0f, 0.0f, 0.0f);
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}
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ccl_device float3 bsdf_hair_transmission_eval_transmit(const ShaderClosure *sc,
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const float3 I,
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const float3 omega_in,
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float *pdf)
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{
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const HairBsdf *bsdf = (const HairBsdf *)sc;
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float offset = bsdf->offset;
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float3 Tg = bsdf->T;
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float roughness1 = bsdf->roughness1;
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float roughness2 = bsdf->roughness2;
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float Iz = dot(Tg, I);
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float3 locy = normalize(I - Tg * Iz);
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float theta_r = M_PI_2_F - fast_acosf(Iz);
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float omega_in_z = dot(Tg, omega_in);
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float3 omega_in_y = normalize(omega_in - Tg * omega_in_z);
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float theta_i = M_PI_2_F - fast_acosf(omega_in_z);
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float phi_i = fast_acosf(dot(omega_in_y, locy));
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if (M_PI_2_F - fabsf(theta_i) < 0.001f) {
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*pdf = 0.0f;
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return make_float3(*pdf, *pdf, *pdf);
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}
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float costheta_i = fast_cosf(theta_i);
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float roughness1_inv = 1.0f / roughness1;
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float a_TT = fast_atan2f(((M_PI_2_F + theta_r) / 2 - offset) * roughness1_inv, 1.0f);
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float b_TT = fast_atan2f(((-M_PI_2_F + theta_r) / 2 - offset) * roughness1_inv, 1.0f);
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float c_TT = 2 * fast_atan2f(M_PI_2_F / roughness2, 1.0f);
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float theta_h = (theta_i + theta_r) / 2;
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float t = theta_h - offset;
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float phi = fabsf(phi_i);
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float p = M_PI_F - phi;
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float theta_pdf = roughness1 /
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(2 * (t * t + roughness1 * roughness1) * (a_TT - b_TT) * costheta_i);
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float phi_pdf = roughness2 / (c_TT * (p * p + roughness2 * roughness2));
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*pdf = phi_pdf * theta_pdf;
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return make_float3(*pdf, *pdf, *pdf);
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}
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ccl_device int bsdf_hair_reflection_sample(const ShaderClosure *sc,
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float3 Ng,
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float3 I,
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float3 dIdx,
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float3 dIdy,
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float randu,
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float randv,
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float3 *eval,
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float3 *omega_in,
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float3 *domega_in_dx,
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float3 *domega_in_dy,
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float *pdf)
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{
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const HairBsdf *bsdf = (const HairBsdf *)sc;
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float offset = bsdf->offset;
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float3 Tg = bsdf->T;
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float roughness1 = bsdf->roughness1;
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float roughness2 = bsdf->roughness2;
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float Iz = dot(Tg, I);
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float3 locy = normalize(I - Tg * Iz);
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float3 locx = cross(locy, Tg);
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float theta_r = M_PI_2_F - fast_acosf(Iz);
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float roughness1_inv = 1.0f / roughness1;
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float a_R = fast_atan2f(((M_PI_2_F + theta_r) * 0.5f - offset) * roughness1_inv, 1.0f);
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float b_R = fast_atan2f(((-M_PI_2_F + theta_r) * 0.5f - offset) * roughness1_inv, 1.0f);
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float t = roughness1 * tanf(randu * (a_R - b_R) + b_R);
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float theta_h = t + offset;
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float theta_i = 2 * theta_h - theta_r;
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float costheta_i, sintheta_i;
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fast_sincosf(theta_i, &sintheta_i, &costheta_i);
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float phi = 2 * safe_asinf(1 - 2 * randv) * roughness2;
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float phi_pdf = fast_cosf(phi * 0.5f) * 0.25f / roughness2;
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float theta_pdf = roughness1 /
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(2 * (t * t + roughness1 * roughness1) * (a_R - b_R) * costheta_i);
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float sinphi, cosphi;
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fast_sincosf(phi, &sinphi, &cosphi);
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*omega_in = (cosphi * costheta_i) * locy - (sinphi * costheta_i) * locx + (sintheta_i)*Tg;
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// differentials - TODO: find a better approximation for the reflective bounce
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#ifdef __RAY_DIFFERENTIALS__
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*domega_in_dx = 2 * dot(locy, dIdx) * locy - dIdx;
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*domega_in_dy = 2 * dot(locy, dIdy) * locy - dIdy;
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#endif
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*pdf = fabsf(phi_pdf * theta_pdf);
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if (M_PI_2_F - fabsf(theta_i) < 0.001f)
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*pdf = 0.0f;
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*eval = make_float3(*pdf, *pdf, *pdf);
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return LABEL_REFLECT | LABEL_GLOSSY;
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}
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ccl_device int bsdf_hair_transmission_sample(const ShaderClosure *sc,
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float3 Ng,
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float3 I,
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float3 dIdx,
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float3 dIdy,
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float randu,
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float randv,
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float3 *eval,
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float3 *omega_in,
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float3 *domega_in_dx,
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float3 *domega_in_dy,
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float *pdf)
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{
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const HairBsdf *bsdf = (const HairBsdf *)sc;
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float offset = bsdf->offset;
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float3 Tg = bsdf->T;
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float roughness1 = bsdf->roughness1;
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float roughness2 = bsdf->roughness2;
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float Iz = dot(Tg, I);
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float3 locy = normalize(I - Tg * Iz);
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float3 locx = cross(locy, Tg);
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float theta_r = M_PI_2_F - fast_acosf(Iz);
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float roughness1_inv = 1.0f / roughness1;
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float a_TT = fast_atan2f(((M_PI_2_F + theta_r) / 2 - offset) * roughness1_inv, 1.0f);
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float b_TT = fast_atan2f(((-M_PI_2_F + theta_r) / 2 - offset) * roughness1_inv, 1.0f);
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float c_TT = 2 * fast_atan2f(M_PI_2_F / roughness2, 1.0f);
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float t = roughness1 * tanf(randu * (a_TT - b_TT) + b_TT);
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float theta_h = t + offset;
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float theta_i = 2 * theta_h - theta_r;
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float costheta_i, sintheta_i;
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fast_sincosf(theta_i, &sintheta_i, &costheta_i);
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float p = roughness2 * tanf(c_TT * (randv - 0.5f));
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float phi = p + M_PI_F;
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float theta_pdf = roughness1 /
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(2 * (t * t + roughness1 * roughness1) * (a_TT - b_TT) * costheta_i);
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float phi_pdf = roughness2 / (c_TT * (p * p + roughness2 * roughness2));
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float sinphi, cosphi;
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fast_sincosf(phi, &sinphi, &cosphi);
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*omega_in = (cosphi * costheta_i) * locy - (sinphi * costheta_i) * locx + (sintheta_i)*Tg;
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// differentials - TODO: find a better approximation for the transmission bounce
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#ifdef __RAY_DIFFERENTIALS__
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*domega_in_dx = 2 * dot(locy, dIdx) * locy - dIdx;
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*domega_in_dy = 2 * dot(locy, dIdy) * locy - dIdy;
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#endif
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*pdf = fabsf(phi_pdf * theta_pdf);
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if (M_PI_2_F - fabsf(theta_i) < 0.001f) {
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*pdf = 0.0f;
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}
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*eval = make_float3(*pdf, *pdf, *pdf);
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/* TODO(sergey): Should always be negative, but seems some precision issue
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* is involved here.
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*/
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kernel_assert(dot(locy, *omega_in) < 1e-4f);
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return LABEL_TRANSMIT | LABEL_GLOSSY;
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}
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CCL_NAMESPACE_END
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#endif /* __BSDF_HAIR_H__ */
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