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/**********************************************************************
* $Id: SegmentSnapper.cpp,v 1.3 2004/12/08 13:54:43 strk Exp $
*
* GEOS - Geometry Engine Open Source
* http://geos.refractions.net
*
* Copyright (C) 2001-2002 Vivid Solutions Inc.
*
* This is free software; you can redistribute and/or modify it under
* the terms of the GNU Lesser General Licence as published
* by the Free Software Foundation.
* See the COPYING file for more information.
*
**********************************************************************
* $Log: SegmentSnapper.cpp,v $
* Revision 1.3 2004/12/08 13:54:43 strk
* gcc warnings checked and fixed, general cleanups.
*
* Revision 1.2 2004/07/02 13:28:27 strk
* Fixed all #include lines to reflect headers layout change.
* Added client application build tips in README.
*
* Revision 1.1 2004/03/29 06:59:25 ybychkov
* "noding/snapround" package ported (JTS 1.4);
* "operation", "operation/valid", "operation/relate" and "operation/overlay" upgraded to JTS 1.4;
* "geom" partially upgraded.
*
*
**********************************************************************/
#include <geos/nodingSnapround.h>
#include <math.h>
namespace geos {
double SegmentSnapper::TOLERANCE=0.5;
/**
* @return true if the point p is within the snap tolerance of the line p0-p1
*/
bool SegmentSnapper::isWithinTolerance(const Coordinate& p,const Coordinate& p0,const Coordinate& p1){
double minx = p.x - TOLERANCE;
double maxx = p.x + TOLERANCE;
double miny = p.y - TOLERANCE;
double maxy = p.y + TOLERANCE;
double segMinx = min(p0.x, p1.x);
double segMaxx = max(p0.x, p1.x);
double segMiny = min(p0.y, p1.y);
double segMaxy = max(p0.y, p1.y);
if ( maxx < segMinx
|| minx > segMaxx
|| maxy < segMiny
|| miny > segMaxy) return false;
double dx = p1.x - p0.x;
double dy = p1.y - p0.y;
double px = p.x - p0.x;
double py = p.y - p0.y;
//double dely = px * dy / dx - py;
//double delx = py * dx / dy - px;
double discy = px * dy - py * dx;
if (fabs(discy) < fabs(0.5 * dx) ) return true;
double discx = py * dx - px * dy;
if (fabs(discx) < fabs(0.5 * dy) ) return true;
return false;
}
/**
* Adds a new node (equal to the snap pt) to the segment
* if the snapPt is
* within tolerance of the segment
*
* @param snapPt
* @param segStr
* @param segIndex
* @return <code>true</code> if a node was added
*/
bool SegmentSnapper::addSnappedNode(Coordinate& snapPt,SegmentString *segStr, int segIndex){
Coordinate p0 = segStr->getCoordinate(segIndex);
Coordinate p1 = segStr->getCoordinate(segIndex + 1);
// no need to snap if the snapPt equals an endpoint of the segment
if (snapPt==p0) return false;
if (snapPt==p1) return false;
if (isWithinTolerance(snapPt, p0, p1)) {
segStr->addIntersection(snapPt, segIndex);
return true;
}
return false;
}
}
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