PostGIS  2.3.7dev-r@@SVN_REVISION@@
int lw_dist2d_pre_seg_seg ( POINTARRAY l1,
POINTARRAY l2,
LISTSTRUCT list1,
LISTSTRUCT list2,
double  k,
DISTPTS dl 
)

preparation before lw_dist2d_seg_seg.

Definition at line 2070 of file measures.c.

References DISTPTS::distance, getPoint2d_cp(), lw_dist2d_pt_pt(), lw_dist2d_selected_seg_seg(), LW_FALSE, LW_TRUE, LWDEBUG, POINTARRAY::npoints, rect_node::p1, rect_node::p2, LISTSTRUCT::pnr, r, DISTPTS::twisted, POINT2D::x, and POINT2D::y.

Referenced by lw_dist2d_fast_ptarray_ptarray().

2071 {
2072  const POINT2D *p1, *p2, *p3, *p4, *p01, *p02;
2073  int pnr1,pnr2,pnr3,pnr4, n1, n2, i, u, r, twist;
2074  double maxmeasure;
2075  n1= l1->npoints;
2076  n2 = l2->npoints;
2077 
2078  LWDEBUG(2, "lw_dist2d_pre_seg_seg is called");
2079 
2080  p1 = getPoint2d_cp(l1, list1[0].pnr);
2081  p3 = getPoint2d_cp(l2, list2[0].pnr);
2082  lw_dist2d_pt_pt(p1, p3, dl);
2083  maxmeasure = sqrt(dl->distance*dl->distance + (dl->distance*dl->distance*k*k));
2084  twist = dl->twisted; /*to keep the incomming order between iterations*/
2085  for (i =(n1-1); i>=0; --i)
2086  {
2087  /*we break this iteration when we have checked every
2088  point closer to our perpendicular "checkline" than
2089  our shortest found distance*/
2090  if (((list2[0].themeasure-list1[i].themeasure)) > maxmeasure) break;
2091  for (r=-1; r<=1; r +=2) /*because we are not iterating in the original pointorder we have to check the segment before and after every point*/
2092  {
2093  pnr1 = list1[i].pnr;
2094  p1 = getPoint2d_cp(l1, pnr1);
2095  if (pnr1+r<0)
2096  {
2097  p01 = getPoint2d_cp(l1, (n1-1));
2098  if (( p1->x == p01->x) && (p1->y == p01->y)) pnr2 = (n1-1);
2099  else pnr2 = pnr1; /* if it is a line and the last and first point is not the same we avoid the edge between start and end this way*/
2100  }
2101 
2102  else if (pnr1+r>(n1-1))
2103  {
2104  p01 = getPoint2d_cp(l1, 0);
2105  if (( p1->x == p01->x) && (p1->y == p01->y)) pnr2 = 0;
2106  else pnr2 = pnr1; /* if it is a line and the last and first point is not the same we avoid the edge between start and end this way*/
2107  }
2108  else pnr2 = pnr1+r;
2109 
2110 
2111  p2 = getPoint2d_cp(l1, pnr2);
2112  for (u=0; u<n2; ++u)
2113  {
2114  if (((list2[u].themeasure-list1[i].themeasure)) >= maxmeasure) break;
2115  pnr3 = list2[u].pnr;
2116  p3 = getPoint2d_cp(l2, pnr3);
2117  if (pnr3==0)
2118  {
2119  p02 = getPoint2d_cp(l2, (n2-1));
2120  if (( p3->x == p02->x) && (p3->y == p02->y)) pnr4 = (n2-1);
2121  else pnr4 = pnr3; /* if it is a line and the last and first point is not the same we avoid the edge between start and end this way*/
2122  }
2123  else pnr4 = pnr3-1;
2124 
2125  p4 = getPoint2d_cp(l2, pnr4);
2126  dl->twisted=twist;
2127  if (!lw_dist2d_selected_seg_seg(p1, p2, p3, p4, dl)) return LW_FALSE;
2128 
2129  if (pnr3>=(n2-1))
2130  {
2131  p02 = getPoint2d_cp(l2, 0);
2132  if (( p3->x == p02->x) && (p3->y == p02->y)) pnr4 = 0;
2133  else pnr4 = pnr3; /* if it is a line and the last and first point is not the same we avoid the edge between start and end this way*/
2134  }
2135 
2136  else pnr4 = pnr3+1;
2137 
2138  p4 = getPoint2d_cp(l2, pnr4);
2139  dl->twisted=twist; /*we reset the "twist" for each iteration*/
2140  if (!lw_dist2d_selected_seg_seg(p1, p2, p3, p4, dl)) return LW_FALSE;
2141 
2142  maxmeasure = sqrt(dl->distance*dl->distance + (dl->distance*dl->distance*k*k));/*here we "translate" the found mindistance so it can be compared to our "z"-values*/
2143  }
2144  }
2145  }
2146 
2147  return LW_TRUE;
2148 }
char * r
Definition: cu_in_wkt.c:24
int npoints
Definition: liblwgeom.h:370
#define LWDEBUG(level, msg)
Definition: lwgeom_log.h:83
double x
Definition: liblwgeom.h:327
#define LW_FALSE
Definition: liblwgeom.h:76
const POINT2D * getPoint2d_cp(const POINTARRAY *pa, int n)
Returns a POINT2D pointer into the POINTARRAY serialized_ptlist, suitable for reading from...
Definition: lwgeom_api.c:485
#define LW_TRUE
Return types for functions with status returns.
Definition: liblwgeom.h:75
double y
Definition: liblwgeom.h:327
int twisted
Definition: measures.h:52
int lw_dist2d_selected_seg_seg(const POINT2D *A, const POINT2D *B, const POINT2D *C, const POINT2D *D, DISTPTS *dl)
This is the same function as lw_dist2d_seg_seg but without any calculations to determine intersection...
Definition: measures.c:2157
double distance
Definition: measures.h:48
int lw_dist2d_pt_pt(const POINT2D *thep1, const POINT2D *thep2, DISTPTS *dl)
Compares incomming points and stores the points closest to each other or most far away from each othe...
Definition: measures.c:2279
int pnr
Definition: measures.h:59

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