PostGIS  2.3.8dev-r@@SVN_REVISION@@

◆ lw_dist2d_pre_seg_seg()

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 2071 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().

2072 {
2073  const POINT2D *p1, *p2, *p3, *p4, *p01, *p02;
2074  int pnr1,pnr2,pnr3,pnr4, n1, n2, i, u, r, twist;
2075  double maxmeasure;
2076  n1= l1->npoints;
2077  n2 = l2->npoints;
2078 
2079  LWDEBUG(2, "lw_dist2d_pre_seg_seg is called");
2080 
2081  p1 = getPoint2d_cp(l1, list1[0].pnr);
2082  p3 = getPoint2d_cp(l2, list2[0].pnr);
2083  lw_dist2d_pt_pt(p1, p3, dl);
2084  maxmeasure = sqrt(dl->distance*dl->distance + (dl->distance*dl->distance*k*k));
2085  twist = dl->twisted; /*to keep the incomming order between iterations*/
2086  for (i =(n1-1); i>=0; --i)
2087  {
2088  /*we break this iteration when we have checked every
2089  point closer to our perpendicular "checkline" than
2090  our shortest found distance*/
2091  if (((list2[0].themeasure-list1[i].themeasure)) > maxmeasure) break;
2092  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*/
2093  {
2094  pnr1 = list1[i].pnr;
2095  p1 = getPoint2d_cp(l1, pnr1);
2096  if (pnr1+r<0)
2097  {
2098  p01 = getPoint2d_cp(l1, (n1-1));
2099  if (( p1->x == p01->x) && (p1->y == p01->y)) pnr2 = (n1-1);
2100  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*/
2101  }
2102 
2103  else if (pnr1+r>(n1-1))
2104  {
2105  p01 = getPoint2d_cp(l1, 0);
2106  if (( p1->x == p01->x) && (p1->y == p01->y)) pnr2 = 0;
2107  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*/
2108  }
2109  else pnr2 = pnr1+r;
2110 
2111 
2112  p2 = getPoint2d_cp(l1, pnr2);
2113  for (u=0; u<n2; ++u)
2114  {
2115  if (((list2[u].themeasure-list1[i].themeasure)) >= maxmeasure) break;
2116  pnr3 = list2[u].pnr;
2117  p3 = getPoint2d_cp(l2, pnr3);
2118  if (pnr3==0)
2119  {
2120  p02 = getPoint2d_cp(l2, (n2-1));
2121  if (( p3->x == p02->x) && (p3->y == p02->y)) pnr4 = (n2-1);
2122  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*/
2123  }
2124  else pnr4 = pnr3-1;
2125 
2126  p4 = getPoint2d_cp(l2, pnr4);
2127  dl->twisted=twist;
2128  if (!lw_dist2d_selected_seg_seg(p1, p2, p3, p4, dl)) return LW_FALSE;
2129 
2130  if (pnr3>=(n2-1))
2131  {
2132  p02 = getPoint2d_cp(l2, 0);
2133  if (( p3->x == p02->x) && (p3->y == p02->y)) pnr4 = 0;
2134  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*/
2135  }
2136 
2137  else pnr4 = pnr3+1;
2138 
2139  p4 = getPoint2d_cp(l2, pnr4);
2140  dl->twisted=twist; /*we reset the "twist" for each iteration*/
2141  if (!lw_dist2d_selected_seg_seg(p1, p2, p3, p4, dl)) return LW_FALSE;
2142 
2143  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*/
2144  }
2145  }
2146  }
2147 
2148  return LW_TRUE;
2149 }
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:2158
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:2280
int pnr
Definition: measures.h:59
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