_lwt_GetInteriorEdgePoint()

static int _lwt_GetInteriorEdgePoint ( const LWLINE *  edge, POINT2D *  ip  )

static

Definition at line 1725 of file lwgeom_topo.c.

References getPoint2d_p(), POINTARRAY::npoints, p2d_same(), LWLINE::points, POINT2D::x, and POINT2D::y.

Referenced by _lwt_AddFaceSplit(), and lwt_ChangeEdgeGeom().

{
  int i;
  POINT2D fp, lp, tp;
  POINTARRAY *pa = edge->points;

  if ( pa->npoints < 2 ) return 0; /* empty or structurally collapsed */

  getPoint2d_p(pa, 0, &fp); /* save first point */
  getPoint2d_p(pa, pa->npoints-1, &lp); /* save last point */
  for (i=1; i<pa->npoints-1; ++i)
  {
    getPoint2d_p(pa, i, &tp); /* pick next point */
    if ( p2d_same(&tp, &fp) ) continue; /* equal to startpoint */
    if ( p2d_same(&tp, &lp) ) continue; /* equal to endpoint */
    /* this is a good one, neither same of start nor of end point */
    *ip = tp;
    return 1; /* found */
  }

  /* no distinct vertex found */

  /* interpolate if start point != end point */

  if ( p2d_same(&fp, &lp) ) return 0; /* no distinct points in edge */

  ip->x = fp.x + ( (lp.x - fp.x) * 0.5 );
  ip->y = fp.y + ( (lp.y - fp.y) * 0.5 );

  return 1;
}

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