67 lines
1.9 KiB
C++
67 lines
1.9 KiB
C++
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#include <mitsuba/render/rfilter.h>
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MTS_NAMESPACE_BEGIN
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/**
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* Separable reconstruction filter by Mitchell and Netravali
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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 size in pixels */
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Float halfSize = props.getFloat("halfSize", 2.0f);
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m_size = Vector2(halfSize, halfSize);
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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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Float halfSize = stream->readFloat();
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m_size = Vector2(halfSize, halfSize);
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m_B = stream->readFloat();
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m_C = stream->readFloat();
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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_size.x);
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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 evaluate(Float x, Float y) const {
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return mitchellNetravali(2.0f * x / m_size.x)
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* mitchellNetravali(2.0f * y / m_size.y);
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}
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Float mitchellNetravali(Float x) const {
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x = std::abs(x);
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Float xSquared = x*x, xCubed = xSquared*x;
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if (x < 1) {
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return 1.0f/6.0f * ((12-9*m_B-6*m_C)*xCubed
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+ (-18+12*m_B+6*m_C) * xSquared + (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)*xCubed + (6*m_B+30*m_C) * xSquared
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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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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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