67 lines
1.9 KiB
C++
67 lines
1.9 KiB
C++
/*
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This file is part of Mitsuba, a physically based rendering system.
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Copyright (c) 2007-2012 by Wenzel Jakob and others.
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Mitsuba is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License Version 3
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as published by the Free Software Foundation.
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Mitsuba is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <mitsuba/core/rfilter.h>
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MTS_NAMESPACE_BEGIN
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/**
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* Special version of the Mitchell-Netravali filter with constants B and C configured
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* to match the Catmull-Rom spline. It usually does a better job at at preserving sharp
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* features at the cost of more ringing.
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*/
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class CatmullRomFilter : public ReconstructionFilter {
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public:
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CatmullRomFilter(const Properties &props)
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: ReconstructionFilter(props) {
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m_radius = 2.0f;
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}
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CatmullRomFilter(Stream *stream, InstanceManager *manager)
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: ReconstructionFilter(stream, manager) {
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configure();
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}
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Float eval(Float x) const {
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x = std::abs(x);
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Float x2 = x*x, x3 = x2*x;
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Float B = 0.0f, C = 0.5f;
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if (x < 1) {
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return 1.0f/6.0f * ((12-9*B-6*C)*x3
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+ (-18+12*B+6*C) * x2 + (6-2*B));
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} else if (x < 2) {
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return 1.0f/6.0f * ((-B-6*C)*x3 + (6*B+30*C) * x2
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+ (-12*B-48*C) * x + (8*B + 24*C));
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} else {
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return 0.0f;
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}
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}
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std::string toString() const {
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return formatString("CatmullRomFilter[radius=%f]", m_radius);
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}
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MTS_DECLARE_CLASS()
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};
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MTS_IMPLEMENT_CLASS_S(CatmullRomFilter, false, ReconstructionFilter);
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MTS_EXPORT_PLUGIN(CatmullRomFilter, "Catmull-Rom filter");
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MTS_NAMESPACE_END
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