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/**********************************************************************
* $Id: HCoordinate.cpp,v 1.12 2004/11/29 16:05:33 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 Public Licence as published
* by the Free Software Foundation.
* See the COPYING file for more information.
*
**********************************************************************/
#include <geos/geosAlgorithm.h>
#include <geos/platform.h>
namespace geos {
/*
* Computes the (approximate) intersection point between two line segments
* using homogeneous coordinates.
*
* Note that this algorithm is
* not numerically stable; i.e. it can produce intersection points which
* lie outside the envelope of the line segments themselves. In order
* to increase the precision of the calculation input points should be
* normalized before passing them to this routine.
*/
Coordinate*
HCoordinate::intersection(Coordinate& p1,Coordinate& p2,Coordinate& q1,Coordinate& q2)
{
auto_ptr<HCoordinate> intHCoord(new HCoordinate(HCoordinate(HCoordinate(p1),HCoordinate(p2)),HCoordinate(HCoordinate(q1),HCoordinate(q2))));
return intHCoord->getCoordinate();
}
HCoordinate::HCoordinate(){
x = 0.0;
y = 0.0;
w = 1.0;
}
HCoordinate::HCoordinate(double _x, double _y, double _w) {
x = _x;
y = _y;
w = _w;
}
HCoordinate::HCoordinate(Coordinate& p) {
x = p.x;
y = p.y;
w = 1.0;
}
HCoordinate::HCoordinate(HCoordinate p1, HCoordinate p2) {
x = p1.y*p2.w - p2.y*p1.w;
y = p2.x*p1.w - p1.x*p2.w;
w = p1.x*p2.y - p2.x*p1.y;
}
double HCoordinate::getX() {
double a = x/w;
if (!FINITE(a))
{
throw new NotRepresentableException();
}
return a;
}
double
HCoordinate::getY()
{
double a = y/w;
if (!FINITE(a))
{
throw new NotRepresentableException();
}
return a;
}
Coordinate* HCoordinate::getCoordinate() {
return new Coordinate(getX(),getY());
}
} // namespace geos
/**********************************************************************
* $Log: HCoordinate.cpp,v $
* Revision 1.12 2004/11/29 16:05:33 strk
* Fixed a bug in LineIntersector::interpolateZ causing NaN values
* to come out.
* Handled dimensional collapses in ElevationMatrix.
* Added ISNAN macro and changed ISNAN/FINITE macros to avoid
* dispendious isnan() and finite() calls.
*
* Revision 1.11 2004/10/20 17:32:14 strk
* Initial approach to 2.5d intersection()
*
* Revision 1.10 2004/07/02 13:28:26 strk
* Fixed all #include lines to reflect headers layout change.
* Added client application build tips in README.
*
* Revision 1.9 2003/11/07 01:23:42 pramsey
* Add standard CVS headers licence notices and copyrights to all cpp and h
* files.
*
*
**********************************************************************/
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