CGAL users discussion list

[Ariel Keselman <>]

Dear all,

I need to calculate the distance from a point to the
vertices of the cell that contains it, in a periodic
Delaunay triangulation. This is done to interpolate
a function with the inverse distance method.

The most obvious way to do this, and the one I
implemented, is to take the periodic_point from the
cell, and then calcule dx,dy,dz between the
periodic_point and the point. In those directions
where the difference is too large, (say, >box_len/2)
the point is translated by box_len. Here is the
function I use:

inline const tvc 
periodic_r(const PDT& T, const tch& ch,
    const unsigned int i, const tpt& p1) {

    const double blen2=T.domain().xmax()/2.0;
    const tpt p2=T.point(ch,i);
    const tvc rv(p1,p2);
    bool needs_trans=false;
    int ox=0,oy=0,oz=0;
    if (rv.x()>=blen2) {
        needs_trans=true;
        ox=+1;
    }
    if (rv.y()>=blen2) {
        needs_trans=true;
        oy=+1;
    }
    if (rv.z()>=blen2) {
        needs_trans=true;
        oz=+1;
    }
    if (!needs_trans) return rv;
    const tpp tpp1(p1,PDT::Offset(ox,oy,oz));
    const tpt tp1=T.point(tpp1);
    const tvc trv(tp1,p2);
    return trv;
}

My question is, is there a way to do this more efficient?
This function increases the time of  the main loop by
0.1 secs, which is about 5%. It just feels this should
be a one-liner, but being new to CGAL, I can't see how
to improve it...

Thanks in advance,
Ariel.

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