distance2.h

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/****************************************************************************
* VCGLib                                                            o o     *
* Visual and Computer Graphics Library                            o     o   *
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* Copyright(C) 2004                                                \/)\/    *
* Visual Computing Lab                                            /\/|      *
* ISTI - Italian National Research Council                           |      *
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#ifndef __VCG_DISTANCE2
#define __VCG_DISTANCE2

#include <limits>
#include <vcg/space/segment2.h>
#include <vcg/space/intersection2.h>

namespace vcg {

        /*
        * Computes the minimum distance between a two segments
        * @param[in] S0                         The input segment0
        * @param[in] S1                         The input segment1
        * return the distance between the two segments
        */
        template<class ScalarType>
        ScalarType Segment2DSegment2DDistance(const vcg::Segment2<ScalarType> &S0,
                                                                        const vcg::Segment2<ScalarType> &S1,
                                    vcg::Point2<ScalarType> &p_clos0,
                                    vcg::Point2<ScalarType> &p_clos1)
        {
        //first test if they intersect
        vcg::Point2<ScalarType> IntPoint;
        if (vcg:: SegmentSegmentIntersection(S0,S1,IntPoint))
        {
            p_clos0=IntPoint;
            p_clos1=IntPoint;
            return 0;
        }
                vcg::Point2<ScalarType> Pclos0=ClosestPoint(S0,S1.P0());
                vcg::Point2<ScalarType> Pclos1=ClosestPoint(S0,S1.P1());
                vcg::Point2<ScalarType> Pclos2=ClosestPoint(S1,S0.P0());
                vcg::Point2<ScalarType> Pclos3=ClosestPoint(S1,S0.P1());
                ScalarType d0=(Pclos0-S1.P0()).Norm();
                ScalarType d1=(Pclos1-S1.P1()).Norm();
                ScalarType d2=(Pclos2-S0.P0()).Norm();
                ScalarType d3=(Pclos3-S0.P1()).Norm();

        //then return the minimuim distance
        if ((d0<d1)&&(d0<d2)&&(d0<d3))
        {
            p_clos0=Pclos0;
            p_clos1=S1.P0();
            return d0;
        }
        if ((d1<d0)&&(d1<d2)&&(d1<d3))
        {
            p_clos0=Pclos1;
            p_clos1=S1.P1();
            return d1;
        }
        if ((d2<d0)&&(d2<d1)&&(d2<d3))
        {
            p_clos0=S0.P0();
            p_clos1=Pclos2;
            return d2;
        }
        else
        {
            p_clos0=S0.P1();
            p_clos1=Pclos3;
            return d3;
        }
        }


}

#endif