127 lines
4.0 KiB
C++
127 lines
4.0 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) 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/export.h>
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#include <vector>
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#include <memory>
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#include <geos/noding/Noder.h> // for inheritance
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#include <geos/algorithm/LineIntersector.h> // for composition
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#include <geos/geom/Coordinate.h> // for use in vector
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#include <geos/geom/CoordinateSequence.h>
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#include <geos/geom/PrecisionModel.h> // for inlines (should drop)
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#include <geos/noding/SegmentIntersector.h>
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// Forward declarations
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namespace geos {
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namespace geom {
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class PrecisionModel;
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}
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namespace noding {
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class SegmentString;
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class NodedSegmentString;
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namespace snapround {
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class HotPixel;
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}
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}
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}
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namespace geos {
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namespace noding { // geos::noding
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namespace snapround { // geos::noding::snapround
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/**
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* Finds intersections between line segments which will be snap-rounded,
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* and adds them as nodes to the segments.
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*
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* Intersections are detected and computed using full precision.
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* Snapping takes place in a subsequent phase.
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*
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* The intersection points are recorded, so that HotPixels can be created for them.
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*
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* To avoid robustness issues with vertices which lie very close to line segments
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* a heuristic is used:
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* nodes are created if a vertex lies within a tolerance distance
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* of the interior of a segment.
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* The tolerance distance is chosen to be significantly below the snap-rounding grid size.
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* This has empirically proven to eliminate noding failures.
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*/
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class GEOS_DLL SnapRoundingIntersectionAdder: public SegmentIntersector { // implements SegmentIntersector
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private:
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algorithm::LineIntersector li;
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geom::CoordinateSequence intersections;
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// const geom::PrecisionModel* pm;
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double nearnessTol;
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/**
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* If an endpoint of one segment is near
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* the interior of the other segment, add it as an intersection.
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* EXCEPT if the endpoint is also close to a segment endpoint
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* (since this can introduce "zigs" in the linework).
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*
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* This resolves situations where
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* a segment A endpoint is extremely close to another segment B,
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* but is not quite crossing. Due to robustness issues
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* in orientation detection, this can
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* result in the snapped segment A crossing segment B
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* without a node being introduced.
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*/
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void processNearVertex(const geom::CoordinateSequence& seq0,
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std::size_t ptIndex,
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const geom::CoordinateSequence& seq1,
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std::size_t segIndex,
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SegmentString* edge);
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bool isNearSegmentInterior(const geom::CoordinateXY& p, const geom::CoordinateXY& p0, const geom::CoordinateXY& p1) const;
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public:
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SnapRoundingIntersectionAdder(double p_nearnessTol)
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: SegmentIntersector()
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, intersections(geom::CoordinateSequence::XYZM(0))
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, nearnessTol(p_nearnessTol)
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{}
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geom::CoordinateSequence getIntersections() { return std::move(intersections); };
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/**
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* This method is called by clients
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* of the {@link SegmentIntersector} class to process
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* intersections for two segments of the {@link SegmentString}s being intersected.
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* Note that some clients (such as MonotoneChains) may optimize away
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* this call for segment pairs which they have determined do not intersect
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* (e.g. by an disjoint envelope test).
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*/
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void processIntersections(SegmentString* e0, std::size_t segIndex0, SegmentString* e1, std::size_t segIndex1) override;
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/**
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* Always process all intersections
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*
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*/
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bool isDone() const override { return false; }
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};
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} // namespace geos::noding::snapround
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} // namespace geos::noding
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} // namespace geos
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