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/*
* Copyright 2011, Blender Foundation.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <OpenImageIO/fmath.h>
#include <OSL/genclosure.h>
#include "osl_closures.h"
#include "util_math.h"
CCL_NAMESPACE_BEGIN
using namespace OSL;
class OrenNayarClosure : public BSDFClosure {
public:
Vec3 m_N;
float m_sigma;
float m_a, m_b;
OrenNayarClosure() : BSDFClosure(Labels::DIFFUSE) {}
void setup() {
m_sigma = clamp(m_sigma, 0.0f, 1.0f);
float div = 1.0f / (M_PI + ((3.0f * M_PI - 4.0f) / 6.0f) * m_sigma);
m_a = 1.0f * div;
m_b = m_sigma * div;
}
bool mergeable(const ClosurePrimitive *other) const {
const OrenNayarClosure *comp = static_cast<const OrenNayarClosure *>(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 "oren_nayar";
}
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 {
if (m_N.dot(omega_in) > 0.0f) {
pdf = float(0.5 * M_1_PI);
float is = get_intensity(m_N, omega_out, omega_in);
return Color3(is, is, is);
}
else {
pdf = 0.0f;
return Color3(0.0f, 0.0f, 0.0f);
}
}
Color3 eval_transmit(const Vec3& omega_out, const Vec3& omega_in, float& pdf) const {
return Color3(0.0f, 0.0f, 0.0f);
}
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 {
sample_uniform_hemisphere(m_N, omega_out, randu, randv, omega_in, pdf);
if (Ng.dot(omega_in) > 0.0f) {
float is = get_intensity(m_N, omega_out, omega_in);
eval.setValue(is, is, is);
// TODO: find a better approximation for the bounce
domega_in_dx = (2.0f * m_N.dot(domega_out_dx)) * m_N - domega_out_dx;
domega_in_dy = (2.0f * m_N.dot(domega_out_dy)) * m_N - domega_out_dy;
domega_in_dx *= 125.0f;
domega_in_dy *= 125.0f;
}
else {
pdf = 0.0f;
}
return Labels::REFLECT;
}
private:
float get_intensity(Vec3 const& n, Vec3 const& v, Vec3 const& l) const {
float nl = max(n.dot(l), 0.0f);
float nv = max(n.dot(v), 0.0f);
float t = l.dot(v) - nl * nv;
if (t > 0.0f) {
t /= max(nl, nv) + 1e-8f;
}
return nl * (m_a + m_b * t);
}
};
ClosureParam *bsdf_oren_nayar_params()
{
static ClosureParam params[] = {
CLOSURE_VECTOR_PARAM(OrenNayarClosure, m_N),
CLOSURE_FLOAT_PARAM(OrenNayarClosure, m_sigma),
CLOSURE_STRING_KEYPARAM("label"),
CLOSURE_FINISH_PARAM(OrenNayarClosure)
};
return params;
}
CLOSURE_PREPARE(bsdf_oren_nayar_prepare, OrenNayarClosure)
CCL_NAMESPACE_END
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