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/*
* 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.
*/
#include <OpenImageIO/fmath.h>
#include <OSL/genclosure.h>
#include "osl_closures.h"
#include "util_math.h"
CCL_NAMESPACE_BEGIN
using namespace OSL;
class AshikhminVelvetClosure : public BSDFClosure {
public:
Vec3 m_N;
float m_sigma;
float m_invsigma2;
AshikhminVelvetClosure() : BSDFClosure(Labels::DIFFUSE) {}
void setup()
{
m_sigma = max(m_sigma, 0.01f);
m_invsigma2 = 1.0f / (m_sigma * m_sigma);
}
bool mergeable(const ClosurePrimitive *other) const {
const AshikhminVelvetClosure *comp = (const AshikhminVelvetClosure *)other;
return m_N == comp->m_N && m_sigma == comp->m_sigma &&
BSDFClosure::mergeable(other);
}
size_t memsize() const { return sizeof(*this); }
const char *name() const { return "ashikhmin_velvet"; }
void print_on(std::ostream &out) const
{
out << name() << " (";
out << "(" << m_N[0] << ", " << m_N[1] << ", " << m_N[2] << "), ";
out << m_sigma;
out << ")";
}
float albedo(const Vec3 &omega_out) const
{
return 1.0f;
}
Color3 eval_reflect(const Vec3 &omega_out, const Vec3 &omega_in, float& pdf) const
{
float cosNO = m_N.dot(omega_out);
float cosNI = m_N.dot(omega_in);
if (cosNO > 0 && cosNI > 0) {
Vec3 H = omega_in + omega_out;
H.normalize();
float cosNH = m_N.dot(H);
float cosHO = fabsf(omega_out.dot(H));
if(!(fabsf(cosNH) < 1.0f-1e-5f && cosHO > 1e-5f))
return Color3(0, 0, 0);
float cosNHdivHO = cosNH / cosHO;
cosNHdivHO = max(cosNHdivHO, 1e-5f);
float fac1 = 2 * fabsf(cosNHdivHO * cosNO);
float fac2 = 2 * fabsf(cosNHdivHO * cosNI);
float sinNH2 = 1 - cosNH * cosNH;
float sinNH4 = sinNH2 * sinNH2;
float cotangent2 = (cosNH * cosNH) / sinNH2;
float D = expf(-cotangent2 * m_invsigma2) * m_invsigma2 * float(M_1_PI) / sinNH4;
float G = min(1.0f, min(fac1, fac2)); // TODO: derive G from D analytically
float out = 0.25f * (D * G) / cosNO;
pdf = 0.5f * (float) M_1_PI;
return Color3(out, out, out);
}
return Color3(0, 0, 0);
}
Color3 eval_transmit(const Vec3 &omega_out, const Vec3 &omega_in, float& pdf) const
{
return Color3(0, 0, 0);
}
ustring sample(const Vec3 &Ng,
const Vec3 &omega_out, const Vec3 &domega_out_dx, const Vec3 &domega_out_dy,
float randu, float randv,
Vec3 &omega_in, Vec3 &domega_in_dx, Vec3 &domega_in_dy,
float &pdf, Color3 &eval) const
{
// we are viewing the surface from above - send a ray out with uniform
// distribution over the hemisphere
sample_uniform_hemisphere(m_N, omega_out, randu, randv, omega_in, pdf);
if (Ng.dot(omega_in) > 0) {
Vec3 H = omega_in + omega_out;
H.normalize();
float cosNI = m_N.dot(omega_in);
float cosNO = m_N.dot(omega_out);
float cosNH = m_N.dot(H);
float cosHO = fabsf(omega_out.dot(H));
if(fabsf(cosNO) > 1e-5f && fabsf(cosNH) < 1.0f-1e-5f && cosHO > 1e-5f) {
float cosNHdivHO = cosNH / cosHO;
cosNHdivHO = max(cosNHdivHO, 1e-5f);
float fac1 = 2 * fabsf(cosNHdivHO * cosNO);
float fac2 = 2 * fabsf(cosNHdivHO * cosNI);
float sinNH2 = 1 - cosNH * cosNH;
float sinNH4 = sinNH2 * sinNH2;
float cotangent2 = (cosNH * cosNH) / sinNH2;
float D = expf(-cotangent2 * m_invsigma2) * m_invsigma2 * float(M_1_PI) / sinNH4;
float G = min(1.0f, min(fac1, fac2)); // TODO: derive G from D analytically
float power = 0.25f * (D * G) / cosNO;
eval.setValue(power, power, power);
// TODO: find a better approximation for the retroreflective bounce
domega_in_dx = (2 * m_N.dot(domega_out_dx)) * m_N - domega_out_dx;
domega_in_dy = (2 * m_N.dot(domega_out_dy)) * m_N - domega_out_dy;
domega_in_dx *= 125;
domega_in_dy *= 125;
}
else
pdf = 0;
}
else
pdf = 0;
return Labels::REFLECT;
}
};
ClosureParam *bsdf_ashikhmin_velvet_params()
{
static ClosureParam params[] = {
CLOSURE_VECTOR_PARAM(AshikhminVelvetClosure, m_N),
CLOSURE_FLOAT_PARAM(AshikhminVelvetClosure, m_sigma),
CLOSURE_STRING_KEYPARAM("label"),
CLOSURE_FINISH_PARAM(AshikhminVelvetClosure)
};
return params;
}
CLOSURE_PREPARE(bsdf_ashikhmin_velvet_prepare, AshikhminVelvetClosure)
CCL_NAMESPACE_END
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