PostGIS  2.5.0dev-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 2067 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().

2068 {
2069  const POINT2D *p1, *p2, *p3, *p4, *p01, *p02;
2070  int pnr1,pnr2,pnr3,pnr4, n1, n2, i, u, r, twist;
2071  double maxmeasure;
2072  n1= l1->npoints;
2073  n2 = l2->npoints;
2074 
2075  LWDEBUG(2, "lw_dist2d_pre_seg_seg is called");
2076 
2077  p1 = getPoint2d_cp(l1, list1[0].pnr);
2078  p3 = getPoint2d_cp(l2, list2[0].pnr);
2079  lw_dist2d_pt_pt(p1, p3, dl);
2080  maxmeasure = sqrt(dl->distance*dl->distance + (dl->distance*dl->distance*k*k));
2081  twist = dl->twisted; /*to keep the incomming order between iterations*/
2082  for (i =(n1-1); i>=0; --i)
2083  {
2084  /*we break this iteration when we have checked every
2085  point closer to our perpendicular "checkline" than
2086  our shortest found distance*/
2087  if (((list2[0].themeasure-list1[i].themeasure)) > maxmeasure) break;
2088  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*/
2089  {
2090  pnr1 = list1[i].pnr;
2091  p1 = getPoint2d_cp(l1, pnr1);
2092  if (pnr1+r<0)
2093  {
2094  p01 = getPoint2d_cp(l1, (n1-1));
2095  if (( p1->x == p01->x) && (p1->y == p01->y)) pnr2 = (n1-1);
2096  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*/
2097  }
2098 
2099  else if (pnr1+r>(n1-1))
2100  {
2101  p01 = getPoint2d_cp(l1, 0);
2102  if (( p1->x == p01->x) && (p1->y == p01->y)) pnr2 = 0;
2103  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*/
2104  }
2105  else pnr2 = pnr1+r;
2106 
2107 
2108  p2 = getPoint2d_cp(l1, pnr2);
2109  for (u=0; u<n2; ++u)
2110  {
2111  if (((list2[u].themeasure-list1[i].themeasure)) >= maxmeasure) break;
2112  pnr3 = list2[u].pnr;
2113  p3 = getPoint2d_cp(l2, pnr3);
2114  if (pnr3==0)
2115  {
2116  p02 = getPoint2d_cp(l2, (n2-1));
2117  if (( p3->x == p02->x) && (p3->y == p02->y)) pnr4 = (n2-1);
2118  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*/
2119  }
2120  else pnr4 = pnr3-1;
2121 
2122  p4 = getPoint2d_cp(l2, pnr4);
2123  dl->twisted=twist;
2124  if (!lw_dist2d_selected_seg_seg(p1, p2, p3, p4, dl)) return LW_FALSE;
2125 
2126  if (pnr3>=(n2-1))
2127  {
2128  p02 = getPoint2d_cp(l2, 0);
2129  if (( p3->x == p02->x) && (p3->y == p02->y)) pnr4 = 0;
2130  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*/
2131  }
2132 
2133  else pnr4 = pnr3+1;
2134 
2135  p4 = getPoint2d_cp(l2, pnr4);
2136  dl->twisted=twist; /*we reset the "twist" for each iteration*/
2137  if (!lw_dist2d_selected_seg_seg(p1, p2, p3, p4, dl)) return LW_FALSE;
2138 
2139  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*/
2140  }
2141  }
2142  }
2143 
2144  return LW_TRUE;
2145 }
char * r
Definition: cu_in_wkt.c:24
#define LWDEBUG(level, msg)
Definition: lwgeom_log.h:83
double x
Definition: liblwgeom.h:327
#define LW_FALSE
Definition: liblwgeom.h:76
#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:2154
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:2276
const POINT2D * getPoint2d_cp(const POINTARRAY *pa, uint32_t n)
Returns a POINT2D pointer into the POINTARRAY serialized_ptlist, suitable for reading from...
Definition: lwgeom_api.c:364
int pnr
Definition: measures.h:59
uint32_t npoints
Definition: liblwgeom.h:370

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