83 lines
2.4 KiB
C++
83 lines
2.4 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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* Separable cubic spline reconstruction filter by Mitchell and Netravali.
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* This is often a good compromise between sharpness and ringing.
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*
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* D. Mitchell, A. Netravali, Reconstruction filters for computer graphics,
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* Proceedings of SIGGRAPH 88, Computer Graphics 22(4), pp. 221-228, 1988.
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*/
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class MitchellNetravaliFilter : public ReconstructionFilter {
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public:
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MitchellNetravaliFilter(const Properties &props)
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: ReconstructionFilter(props) {
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/* Filter radius */
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m_radius = 2.0f;
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/* B parameter from the paper */
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m_B = props.getFloat("B", 1.0f / 3.0f);
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/* C parameter from the paper */
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m_C = props.getFloat("C", 1.0f / 3.0f);
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}
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MitchellNetravaliFilter(Stream *stream, InstanceManager *manager)
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: ReconstructionFilter(stream, manager) {
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m_B = stream->readFloat();
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m_C = stream->readFloat();
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configure();
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}
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void serialize(Stream *stream, InstanceManager *manager) const {
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ReconstructionFilter::serialize(stream, manager);
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stream->writeFloat(m_B);
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stream->writeFloat(m_C);
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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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if (x < 1) {
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return 1.0f/6.0f * ((12-9*m_B-6*m_C)*x3
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+ (-18+12*m_B+6*m_C) * x2 + (6-2*m_B));
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} else if (x < 2) {
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return 1.0f/6.0f * ((-m_B-6*m_C)*x3 + (6*m_B+30*m_C) * x2
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+ (-12*m_B-48*m_C) * x + (8*m_B + 24*m_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("MitchellNetravaliFilter[radius=%f, B=%f, C=%f]", m_radius, m_B, m_C);
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}
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MTS_DECLARE_CLASS()
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protected:
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Float m_B, m_C;
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};
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MTS_IMPLEMENT_CLASS_S(MitchellNetravaliFilter, false, ReconstructionFilter);
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MTS_EXPORT_PLUGIN(MitchellNetravaliFilter, "Mitchell-Netravali filter");
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MTS_NAMESPACE_END
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