109 lines
3.3 KiB
C++
109 lines
3.3 KiB
C++
/**********************************************************************
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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) 2005-2006 Refractions Research Inc.
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* Copyright (C) 2001-2002 Vivid Solutions Inc.
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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/export.h>
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#include <memory>
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#include <vector>
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#include <geos/geomgraph/index/EdgeSetIntersector.h> // for inheritance
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#include <geos/geomgraph/index/SegmentIntersector.h>
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#include <geos/geomgraph/index/SweepLineEvent.h>
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#include <geos/geomgraph/index/MonotoneChain.h>
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#ifdef _MSC_VER
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#pragma warning(push)
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#pragma warning(disable: 4251) // warning C4251: needs to have dll-interface to be used by clients of class
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#endif
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// Forward declarations
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namespace geos {
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namespace geomgraph {
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class Edge;
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}
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}
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namespace geos {
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namespace geomgraph { // geos::geomgraph
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namespace index { // geos::geomgraph::index
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/** \brief
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* Finds all intersections in one or two sets of edges,
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* using an x-axis sweepline algorithm in conjunction with Monotone Chains.
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*
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* While still O(n^2) in the worst case, this algorithm
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* drastically improves the average-case time.
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* The use of MonotoneChains as the items in the index
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* seems to offer an improvement in performance over a sweep-line alone.
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*/
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class GEOS_DLL SimpleMCSweepLineIntersector: public EdgeSetIntersector {
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public:
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SimpleMCSweepLineIntersector() = default;
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~SimpleMCSweepLineIntersector() override = default;
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void computeIntersections(std::vector<Edge*>* edges,
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SegmentIntersector* si, bool testAllSegments) override;
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void computeIntersections(std::vector<Edge*>* edges0,
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std::vector<Edge*>* edges1,
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SegmentIntersector* si) override;
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protected:
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// SweepLineEvents need to refer to each other, and to MonotoneChains.
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// To avoid individually heap-allocating all of these, we store them
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// in deques so that subsequent inserts preserve addresses. However,
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// we also need to sort the SweepLineEvents after they have all been
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// inserted, so we keep a pointer to each event in a separate vector,
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// which can be freely reordered without breaking linkages.
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std::vector<SweepLineEvent*> events;
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std::deque<SweepLineEvent> eventStore;
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std::deque<MonotoneChain> chains;
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// statistics information
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int nOverlaps;
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private:
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void add(std::vector<Edge*>* edges);
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void add(std::vector<Edge*>* edges, void* edgeSet);
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void add(Edge* edge, void* edgeSet);
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void prepareEvents();
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void computeIntersections(SegmentIntersector* si);
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void processOverlaps(std::size_t start, std::size_t end,
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SweepLineEvent* ev0,
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SegmentIntersector* si);
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// Declare type as noncopyable
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SimpleMCSweepLineIntersector(const SimpleMCSweepLineIntersector& other) = delete;
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SimpleMCSweepLineIntersector& operator=(const SimpleMCSweepLineIntersector& rhs) = delete;
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};
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} // namespace geos.geomgraph.index
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} // namespace geos.geomgraph
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} // namespace geos
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#ifdef _MSC_VER
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#pragma warning(pop)
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#endif
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