92 lines
2.3 KiB
C
92 lines
2.3 KiB
C
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/**********************************************************************
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*
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* GEOS - Geometry Engine Open Source
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* http://geos.osgeo.org
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*
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* Copyright (C) 2020 Paul Ramsey <pramsey@cleverelephant.ca>
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*
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* This is free software; you can redistribute and/or modify it under
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* the terms of the GNU Lesser General Public Licence as published
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* by the Free Software Foundation.
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* See the COPYING file for more information.
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*
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**********************************************************************/
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#pragma once
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#include <geos/geom/CoordinateSequence.h>
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#include <geos/export.h>
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#include <array>
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#include <memory>
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#include <vector>
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// Forward declarations
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namespace geos {
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namespace geom {
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class Envelope;
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class Coordinate;
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class CoordinateSequence;
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}
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}
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using namespace geos::geom;
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namespace geos { // geos.
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namespace operation { // geos.operation
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namespace overlayng { // geos.operation.overlayng
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/**
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* Limits the segments in a list of segments
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* to those which intersect an envelope.
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* This creates zero or more sections of the input segment sequences,
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* containing only line segments which intersect the limit envelope.
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* Segments are not clipped, since that can move
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* line segments enough to alter topology,
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* and it happens in the overlay in any case.
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* This can substantially reduce the number of vertices which need to be
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* processed during overlay.
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*
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* This optimization is only applicable to Line geometries,
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* since it does not maintain the closed topology of rings.
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* Polygonal geometries are optimized using the {@link RingClipper}.
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*
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* @author Martin Davis
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*/
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class GEOS_DLL LineLimiter {
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private:
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// Members
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const Envelope* limitEnv;
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std::unique_ptr<geom::CoordinateSequence> ptList;
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const Coordinate* lastOutside;
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std::vector<std::unique_ptr<CoordinateSequence>> sections;
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// Methods
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void addPoint(const Coordinate* p);
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void addOutside(const Coordinate* p);
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bool isLastSegmentIntersecting(const Coordinate* p);
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bool isSectionOpen();
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void startSection();
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void finishSection();
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public:
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LineLimiter(const Envelope* env)
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: limitEnv(env)
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, ptList(nullptr)
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, lastOutside(nullptr)
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{};
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std::vector<std::unique_ptr<CoordinateSequence>>& limit(const CoordinateSequence *pts);
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};
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} // namespace geos.operation.overlayng
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} // namespace geos.operation
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} // namespace geos
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