160 lines
4.2 KiB
C++
160 lines
4.2 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) 2023 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/export.h>
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#include <vector>
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#include <memory>
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// Forward declarations
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namespace geos {
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namespace geom {
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class CoordinateSequence;
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class CoordinateXY;
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class Geometry;
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class GeometryFactory;
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class LineSegment;
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class LineString;
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class Polygon;
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}
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}
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using geos::geom::CoordinateSequence;
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using geos::geom::CoordinateXY;
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using geos::geom::Geometry;
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using geos::geom::GeometryFactory;
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using geos::geom::LineSegment;
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using geos::geom::LineString;
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using geos::geom::Polygon;
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namespace geos {
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namespace algorithm { // geos::algorithm
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/**
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* Computes the minimum-area rectangle enclosing a Geometry.
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* Unlike the Envelope, the rectangle may not be axis-parallel.
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*
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* The first step in the algorithm is computing the convex hull of the Geometry.
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* If the input Geometry is known to be convex, a hint can be supplied to
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* avoid this computation.
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*
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* In degenerate cases the minimum enclosing geometry
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* may be a LineString or a Point.
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*
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* The minimum-area enclosing rectangle does not necessarily
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* have the minimum possible width.
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* Use MinimumDiameter to compute this.
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*
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* @see MinimumDiameter
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* @see ConvexHull
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*
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*/
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class GEOS_DLL MinimumAreaRectangle {
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private:
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// Members
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const Geometry* m_inputGeom;
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bool m_isConvex;
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// Methods
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std::unique_ptr<Geometry> getMinimumRectangle();
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std::unique_ptr<Geometry> computeConvex(const Geometry* convexGeom);
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/**
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* Computes the minimum-area rectangle for a convex ring of Coordinate.
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*
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* This algorithm uses the "dual rotating calipers" technique.
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* Performance is linear in the number of segments.
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*
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* @param ring the convex ring to scan
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*/
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std::unique_ptr<Polygon> computeConvexRing(const CoordinateSequence* ring);
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std::size_t findFurthestVertex(
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const CoordinateSequence* pts,
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const LineSegment& baseSeg,
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std::size_t startIndex,
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int orient);
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bool isFurtherOrEqual(double d1, double d2, int orient);
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static double orientedDistance(
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const LineSegment& seg,
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const CoordinateXY& p,
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int orient);
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static std::size_t getNextIndex(
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const CoordinateSequence* ring,
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std::size_t index);
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/**
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* Creates a line of maximum extent from the provided vertices
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* @param pts the vertices
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* @param factory the geometry factory
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* @return the line of maximum extent
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*/
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static std::unique_ptr<LineString> computeMaximumLine(
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const CoordinateSequence* pts,
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const GeometryFactory* factory);
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public:
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/**
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* Compute a minimum-area rectangle for a given Geometry.
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*
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* @param inputGeom a Geometry
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*/
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MinimumAreaRectangle(const Geometry* inputGeom)
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: m_inputGeom(inputGeom)
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, m_isConvex(false)
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{};
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/**
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* Compute a minimum rectangle for a Geometry,
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* with a hint if the geometry is convex
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* (e.g. a convex Polygon or LinearRing,
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* or a two-point LineString, or a Point).
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*
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* @param inputGeom a Geometry which is convex
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* @param isConvex true if the input geometry is convex
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*/
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MinimumAreaRectangle(const Geometry* inputGeom, bool isConvex)
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: m_inputGeom(inputGeom)
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, m_isConvex(isConvex)
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{};
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/**
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* Gets the minimum-area rectangular Polygon which encloses the input geometry.
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* If the convex hull of the input is degenerate (a line or point)
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* a LineString or Point is returned.
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*
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* @param geom the geometry
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* @return the minimum rectangle enclosing the geometry
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*/
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static std::unique_ptr<Geometry> getMinimumRectangle(const Geometry* geom);
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};
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} // namespace geos::algorithm
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} // namespace geos
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