kicad/common/geometry/seg.cpp

/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2013 CERN
 * @author Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, you may find one here:
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * or you may search the http://www.gnu.org website for the version 2 license,
 * or you may write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 */


#include <geometry/seg.h>

template <typename T> int sgn(T val) {
    return (T(0) < val) - (val < T(0));
}

bool SEG::PointCloserThan (const VECTOR2I& aP, int dist) const
{
	VECTOR2I   	  d = b - a;
	ecoord dist_sq = (ecoord) dist * dist;

 	SEG::ecoord l_squared = d.Dot(d);
    SEG::ecoord t = d.Dot(aP - a);


    if( t <= 0 || !l_squared )
    	return (aP - a).SquaredEuclideanNorm() < dist_sq;
    else if( t >= l_squared ) 
    	return (aP - b).SquaredEuclideanNorm() < dist_sq;


	int dxdy =  abs(d.x) - abs(d.y);	

    if( (dxdy >= -1 && dxdy <= 1) || abs(d.x) <= 1 || abs(d.y) <= 1)
    {
    	int ca = -sgn(d.y);
    	int cb = sgn(d.x);
    	int cc = -ca * a.x - cb * a.y;
    	
		ecoord num = ca * aP.x + cb * aP.y + cc;
		num *= num;

		if(ca && cb)
			num >>= 1;

		if(num > (dist_sq + 100))
			return false;
		else if(num < (dist_sq - 100))
			return true;
    }

	VECTOR2I nearest;    
    nearest.x = a.x + rescale(t, (ecoord)d.x, l_squared);
    nearest.y = a.y + rescale(t, (ecoord)d.y, l_squared);

    return (nearest - aP).SquaredEuclideanNorm() <= dist_sq;
}

SEG::ecoord SEG::SquaredDistance( const SEG& aSeg ) const 
{
		// fixme: rather inefficient.... 
		if(Intersect(aSeg))
			return 0;

		const VECTOR2I pts[4] =
		{
			aSeg.NearestPoint(a) - a,
			aSeg.NearestPoint(b) - b,
			NearestPoint(aSeg.a) - aSeg.a,
			NearestPoint(aSeg.b) - aSeg.b
			};

		ecoord m = VECTOR2I::ECOORD_MAX;
		for (int i = 0; i<4 ; i++)
			m = std::min(m, pts[i].SquaredEuclideanNorm());
		return m;
}
	
OPT_VECTOR2I SEG::Intersect( const SEG& aSeg, bool aIgnoreEndpoints, bool aLines ) const
{
	const VECTOR2I e (b - a);
	const VECTOR2I f (aSeg.b - aSeg.a);
	const VECTOR2I ac (aSeg.a - a);
	
	ecoord d = f.Cross(e);
	ecoord p = f.Cross(ac);
	ecoord q = e.Cross(ac);
	
	if(d == 0)
		return OPT_VECTOR2I();
	if (!aLines && d > 0 && (q < 0 || q > d || p < 0 || p > d))
		return OPT_VECTOR2I();
	if (!aLines && d < 0 && (q < d || p < d || p > 0 || q > 0))
		return OPT_VECTOR2I();
	if (!aLines && aIgnoreEndpoints && (q == 0 || q == d) && (p == 0 || p == d))
		return OPT_VECTOR2I();
		
	
	 VECTOR2I  ip ( aSeg.a.x + rescale(q, (ecoord)f.x, d),
					  aSeg.a.y + rescale(q, (ecoord)f.y, d) );

	 return ip;
}


bool SEG::ccw ( const VECTOR2I& a, const VECTOR2I& b, const VECTOR2I &c ) const
{
	return (ecoord)(c.y - a.y) * (b.x - a.x) > (ecoord)(b.y - a.y) * (c.x - a.x);
}

bool SEG::Collide( const SEG& aSeg, int aClearance ) const 
{
	// check for intersection 
	// fixme: move to a method
	if( ccw(a,aSeg.a,aSeg.b) != ccw(b,aSeg.a,aSeg.b) && ccw(a,b,aSeg.a) != ccw(a,b,aSeg.b) )
		return true;

#define CHK(_seg, _pt) \
	if( (_seg).PointCloserThan (_pt, aClearance ) ) return true;
	
	CHK(*this, aSeg.a);
	CHK(*this, aSeg.b);
	CHK(aSeg, a);
	CHK(aSeg, b);

#undef CHK

	return false;
}
		
bool SEG::Contains(const VECTOR2I& aP) const
{
	return PointCloserThan(aP, 1);
}