blender/intern/cycles/kernel/osl/bsdf_ashikhmin_velvet.cpp
Ton Roosendaal da376e0237 Cycles render engine, initial commit. This is the engine itself, blender modifications and build instructions will follow later.
Cycles uses code from some great open source projects, many thanks them:

* BVH building and traversal code from NVidia's "Understanding the Efficiency of Ray Traversal on GPUs":
http://code.google.com/p/understanding-the-efficiency-of-ray-traversal-on-gpus/
* Open Shading Language for a large part of the shading system:
http://code.google.com/p/openshadinglanguage/
* Blender for procedural textures and a few other nodes.
* Approximate Catmull Clark subdivision from NVidia Mesh tools:
http://code.google.com/p/nvidia-mesh-tools/
* Sobol direction vectors from:
http://web.maths.unsw.edu.au/~fkuo/sobol/
* Film response functions from:
http://www.cs.columbia.edu/CAVE/software/softlib/dorf.php
2011-04-27 11:58:34 +00:00

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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"
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 = std::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));
float cosNHdivHO = cosNH / cosHO;
cosNHdivHO = std::max(cosNHdivHO, 0.00001f);
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 = std::min(1.0f, std::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));
float cosNHdivHO = cosNH / cosHO;
cosNHdivHO = std::max(cosNHdivHO, 0.00001f);
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 = std::min(1.0f, std::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;
return Labels::REFLECT;
}
};
ClosureParam bsdf_ashikhmin_velvet_params[] = {
CLOSURE_VECTOR_PARAM(AshikhminVelvetClosure, m_N),
CLOSURE_FLOAT_PARAM (AshikhminVelvetClosure, m_sigma),
CLOSURE_STRING_KEYPARAM("label"),
CLOSURE_FINISH_PARAM(AshikhminVelvetClosure) };
CLOSURE_PREPARE(bsdf_ashikhmin_velvet_prepare, AshikhminVelvetClosure)
CCL_NAMESPACE_END