PostGIS  3.0.0dev-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 2072 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, LISTSTRUCT::pnr, r, DISTPTS::twisted, POINT2D::x, and POINT2D::y.

Referenced by lw_dist2d_fast_ptarray_ptarray().

2073 {
2074  const POINT2D *p1, *p2, *p3, *p4, *p01, *p02;
2075  int pnr1,pnr2,pnr3,pnr4, n1, n2, i, u, r, twist;
2076  double maxmeasure;
2077  n1= l1->npoints;
2078  n2 = l2->npoints;
2079 
2080  LWDEBUG(2, "lw_dist2d_pre_seg_seg is called");
2081 
2082  p1 = getPoint2d_cp(l1, list1[0].pnr);
2083  p3 = getPoint2d_cp(l2, list2[0].pnr);
2084  lw_dist2d_pt_pt(p1, p3, dl);
2085  maxmeasure = sqrt(dl->distance*dl->distance + (dl->distance*dl->distance*k*k));
2086  twist = dl->twisted; /*to keep the incoming order between iterations*/
2087  for (i =(n1-1); i>=0; --i)
2088  {
2089  /*we break this iteration when we have checked every
2090  point closer to our perpendicular "checkline" than
2091  our shortest found distance*/
2092  if (((list2[0].themeasure-list1[i].themeasure)) > maxmeasure) break;
2093  for (r=-1; r<=1; r +=2) /*because we are not iterating in the original point order we have to check the segment before and after every point*/
2094  {
2095  pnr1 = list1[i].pnr;
2096  p1 = getPoint2d_cp(l1, pnr1);
2097  if (pnr1+r<0)
2098  {
2099  p01 = getPoint2d_cp(l1, (n1-1));
2100  if (( p1->x == p01->x) && (p1->y == p01->y)) pnr2 = (n1-1);
2101  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*/
2102  }
2103 
2104  else if (pnr1+r>(n1-1))
2105  {
2106  p01 = getPoint2d_cp(l1, 0);
2107  if (( p1->x == p01->x) && (p1->y == p01->y)) pnr2 = 0;
2108  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*/
2109  }
2110  else pnr2 = pnr1+r;
2111 
2112 
2113  p2 = getPoint2d_cp(l1, pnr2);
2114  for (u=0; u<n2; ++u)
2115  {
2116  if (((list2[u].themeasure-list1[i].themeasure)) >= maxmeasure) break;
2117  pnr3 = list2[u].pnr;
2118  p3 = getPoint2d_cp(l2, pnr3);
2119  if (pnr3==0)
2120  {
2121  p02 = getPoint2d_cp(l2, (n2-1));
2122  if (( p3->x == p02->x) && (p3->y == p02->y)) pnr4 = (n2-1);
2123  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*/
2124  }
2125  else pnr4 = pnr3-1;
2126 
2127  p4 = getPoint2d_cp(l2, pnr4);
2128  dl->twisted=twist;
2129  if (!lw_dist2d_selected_seg_seg(p1, p2, p3, p4, dl)) return LW_FALSE;
2130 
2131  if (pnr3>=(n2-1))
2132  {
2133  p02 = getPoint2d_cp(l2, 0);
2134  if (( p3->x == p02->x) && (p3->y == p02->y)) pnr4 = 0;
2135  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*/
2136  }
2137 
2138  else pnr4 = pnr3+1;
2139 
2140  p4 = getPoint2d_cp(l2, pnr4);
2141  dl->twisted=twist; /*we reset the "twist" for each iteration*/
2142  if (!lw_dist2d_selected_seg_seg(p1, p2, p3, p4, dl)) return LW_FALSE;
2143 
2144  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*/
2145  }
2146  }
2147  }
2148 
2149  return LW_TRUE;
2150 }
char * r
Definition: cu_in_wkt.c:24
#define LWDEBUG(level, msg)
Definition: lwgeom_log.h:83
static const POINT2D * getPoint2d_cp(const POINTARRAY *pa, uint32_t n)
Returns a POINT2D pointer into the POINTARRAY serialized_ptlist, suitable for reading from...
Definition: lwinline.h:91
double x
Definition: liblwgeom.h:330
#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:330
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:2159
double distance
Definition: measures.h:48
int lw_dist2d_pt_pt(const POINT2D *thep1, const POINT2D *thep2, DISTPTS *dl)
Compares incoming points and stores the points closest to each other or most far away from each other...
Definition: measures.c:2281
int pnr
Definition: measures.h:59
uint32_t npoints
Definition: liblwgeom.h:373
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