ptarray_arc_length_2d()

double ptarray_arc_length_2d

(

const POINTARRAY *

pts

)

Find the 2d length of the given POINTARRAY, using circular arc interpolation between each coordinate triple.

Length(A1, A2, A3, A4, A5) = Length(A1, A2, A3)+Length(A3, A4, A5)

Definition at line 1730 of file ptarray.c.

{
        double dist = 0.0;
        uint32_t i;
        const POINT2D *a1;
        const POINT2D *a2;
        const POINT2D *a3;
 
        if ( pts->npoints % 2 != 1 )
                lwerror("arc point array with even number of points");
 
        a1 = getPoint2d_cp(pts, 0);
 
        for ( i=2; i < pts->npoints; i += 2 )
        {
                a2 = getPoint2d_cp(pts, i-1);
                a3 = getPoint2d_cp(pts, i);
                dist += lw_arc_length(a1, a2, a3);
                a1 = a3;
        }
        return dist;
}

References getPoint2d_cp(), lw_arc_length(), lwerror(), and POINTARRAY::npoints.

Referenced by lwcircstring_length_2d().

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