forked from bartvdbraak/blender
227 lines
7.7 KiB
C++
227 lines
7.7 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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#include <OpenImageIO/fmath.h>
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#include <OSL/genclosure.h>
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#include "osl_closures.h"
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#include "util_math.h"
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CCL_NAMESPACE_BEGIN
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using namespace OSL;
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// anisotropic ward - leaks energy at grazing angles
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// see http://www.graphics.cornell.edu/~bjw/wardnotes.pdf
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class WardClosure : public BSDFClosure {
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public:
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Vec3 m_N;
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Vec3 m_T;
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float m_ax, m_ay;
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WardClosure() : BSDFClosure(Labels::GLOSSY) {}
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void setup()
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{
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m_ax = clamp(m_ax, 1e-5f, 1.0f);
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m_ay = clamp(m_ay, 1e-5f, 1.0f);
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}
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bool mergeable(const ClosurePrimitive *other) const {
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const WardClosure *comp = (const WardClosure *)other;
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return m_N == comp->m_N && m_T == comp->m_T &&
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m_ax == comp->m_ax && m_ay == comp->m_ay &&
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BSDFClosure::mergeable(other);
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}
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size_t memsize() const { return sizeof(*this); }
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const char *name() const { return "ward"; }
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void print_on(std::ostream &out) const {
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out << name() << " ((";
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out << m_N[0] << ", " << m_N[1] << ", " << m_N[2] << "), (";
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out << m_T[0] << ", " << m_T[1] << ", " << m_T[2] << "), ";
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out << m_ax << ", " << m_ay << ")";
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}
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float albedo(const Vec3 &omega_out) const
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{
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return 1.0f;
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}
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Color3 eval_reflect(const Vec3 &omega_out, const Vec3 &omega_in, float& pdf) const
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{
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float cosNO = m_N.dot(omega_out);
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float cosNI = m_N.dot(omega_in);
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if (cosNI > 0 && cosNO > 0) {
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// get half vector and get x,y basis on the surface for anisotropy
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Vec3 H = omega_in + omega_out;
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H.normalize(); // normalize needed for pdf
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Vec3 X, Y;
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make_orthonormals(m_N, m_T, X, Y);
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// eq. 4
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float dotx = H.dot(X) / m_ax;
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float doty = H.dot(Y) / m_ay;
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float dotn = H.dot(m_N);
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float exp_arg = (dotx * dotx + doty * doty) / (dotn * dotn);
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float denom = (4 * (float) M_PI * m_ax * m_ay * sqrtf(cosNO * cosNI));
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float exp_val = expf(-exp_arg);
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float out = cosNI * exp_val / denom;
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float oh = H.dot(omega_out);
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denom = 4 * (float) M_PI * m_ax * m_ay * oh * dotn * dotn * dotn;
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pdf = exp_val / denom;
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return Color3(out, out, out);
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}
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return Color3(0, 0, 0);
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}
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Color3 eval_transmit(const Vec3 &omega_out, const Vec3 &omega_in, float& pdf) const
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{
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return Color3(0, 0, 0);
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}
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ustring sample(const Vec3 &Ng,
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const Vec3 &omega_out, const Vec3 &domega_out_dx, const Vec3 &domega_out_dy,
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float randu, float randv,
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Vec3 &omega_in, Vec3 &domega_in_dx, Vec3 &domega_in_dy,
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float &pdf, Color3 &eval) const
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{
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float cosNO = m_N.dot(omega_out);
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if (cosNO > 0) {
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// get x,y basis on the surface for anisotropy
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Vec3 X, Y;
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make_orthonormals(m_N, m_T, X, Y);
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// generate random angles for the half vector
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// eq. 7 (taking care around discontinuities to keep
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// output angle in the right quadrant)
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// we take advantage of cos(atan(x)) == 1/sqrt(1+x^2)
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// and sin(atan(x)) == x/sqrt(1+x^2)
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float alphaRatio = m_ay / m_ax;
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float cosPhi, sinPhi;
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if (randu < 0.25f) {
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float val = 4 * randu;
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float tanPhi = alphaRatio * tanf((float) M_PI_2 * val);
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cosPhi = 1 / sqrtf(1 + tanPhi * tanPhi);
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sinPhi = tanPhi * cosPhi;
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}
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else if (randu < 0.5) {
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float val = 1 - 4 * (0.5f - randu);
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float tanPhi = alphaRatio * tanf((float) M_PI_2 * val);
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// phi = (float) M_PI - phi;
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cosPhi = -1 / sqrtf(1 + tanPhi * tanPhi);
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sinPhi = -tanPhi * cosPhi;
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}
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else if (randu < 0.75f) {
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float val = 4 * (randu - 0.5f);
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float tanPhi = alphaRatio * tanf((float) M_PI_2 * val);
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//phi = (float) M_PI + phi;
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cosPhi = -1 / sqrtf(1 + tanPhi * tanPhi);
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sinPhi = tanPhi * cosPhi;
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}
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else {
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float val = 1 - 4 * (1 - randu);
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float tanPhi = alphaRatio * tanf((float) M_PI_2 * val);
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// phi = 2 * (float) M_PI - phi;
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cosPhi = 1 / sqrtf(1 + tanPhi * tanPhi);
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sinPhi = -tanPhi * cosPhi;
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}
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// eq. 6
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// we take advantage of cos(atan(x)) == 1/sqrt(1+x^2)
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// and sin(atan(x)) == x/sqrt(1+x^2)
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float thetaDenom = (cosPhi * cosPhi) / (m_ax * m_ax) + (sinPhi * sinPhi) / (m_ay * m_ay);
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float tanTheta2 = -logf(1 - randv) / thetaDenom;
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float cosTheta = 1 / sqrtf(1 + tanTheta2);
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float sinTheta = cosTheta * sqrtf(tanTheta2);
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Vec3 h; // already normalized becaused expressed from spherical coordinates
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h.x = sinTheta * cosPhi;
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h.y = sinTheta * sinPhi;
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h.z = cosTheta;
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// compute terms that are easier in local space
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float dotx = h.x / m_ax;
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float doty = h.y / m_ay;
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float dotn = h.z;
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// transform to world space
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h = h.x * X + h.y * Y + h.z * m_N;
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// generate the final sample
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float oh = h.dot(omega_out);
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omega_in.x = 2 * oh * h.x - omega_out.x;
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omega_in.y = 2 * oh * h.y - omega_out.y;
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omega_in.z = 2 * oh * h.z - omega_out.z;
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if (Ng.dot(omega_in) > 0) {
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float cosNI = m_N.dot(omega_in);
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if (cosNI > 0) {
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// eq. 9
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float exp_arg = (dotx * dotx + doty * doty) / (dotn * dotn);
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float denom = 4 * (float) M_PI * m_ax * m_ay * oh * dotn * dotn * dotn;
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pdf = expf(-exp_arg) / denom;
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// compiler will reuse expressions already computed
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denom = (4 * (float) M_PI * m_ax * m_ay * sqrtf(cosNO * cosNI));
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float power = cosNI * expf(-exp_arg) / denom;
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eval.setValue(power, power, power);
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domega_in_dx = (2 * m_N.dot(domega_out_dx)) * m_N - domega_out_dx;
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domega_in_dy = (2 * m_N.dot(domega_out_dy)) * m_N - domega_out_dy;
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/* disabled for now - gives texture filtering problems */
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#if 0
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// Since there is some blur to this reflection, make the
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// derivatives a bit bigger. In theory this varies with the
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// roughness but the exact relationship is complex and
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// requires more ops than are practical.
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domega_in_dx *= 10;
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domega_in_dy *= 10;
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#endif
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}
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}
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}
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return Labels::REFLECT;
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}
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};
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ClosureParam bsdf_ward_params[] = {
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CLOSURE_VECTOR_PARAM(WardClosure, m_N),
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CLOSURE_VECTOR_PARAM(WardClosure, m_T),
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CLOSURE_FLOAT_PARAM(WardClosure, m_ax),
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CLOSURE_FLOAT_PARAM(WardClosure, m_ay),
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CLOSURE_STRING_KEYPARAM("label"),
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CLOSURE_FINISH_PARAM(WardClosure)
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};
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CLOSURE_PREPARE(bsdf_ward_prepare, WardClosure)
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CCL_NAMESPACE_END
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