PostGIS  2.1.10dev-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 1878 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().

1879 {
1880  const POINT2D *p1, *p2, *p3, *p4, *p01, *p02;
1881  int pnr1,pnr2,pnr3,pnr4, n1, n2, i, u, r, twist;
1882  double maxmeasure;
1883  n1= l1->npoints;
1884  n2 = l2->npoints;
1885 
1886  LWDEBUG(2, "lw_dist2d_pre_seg_seg is called");
1887 
1888  p1 = getPoint2d_cp(l1, list1[0].pnr);
1889  p3 = getPoint2d_cp(l2, list2[0].pnr);
1890  lw_dist2d_pt_pt(p1, p3, dl);
1891  maxmeasure = sqrt(dl->distance*dl->distance + (dl->distance*dl->distance*k*k));
1892  twist = dl->twisted; /*to keep the incomming order between iterations*/
1893  for (i =(n1-1); i>=0; --i)
1894  {
1895  /*we break this iteration when we have checked every
1896  point closer to our perpendicular "checkline" than
1897  our shortest found distance*/
1898  if (((list2[0].themeasure-list1[i].themeasure)) > maxmeasure) break;
1899  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*/
1900  {
1901  pnr1 = list1[i].pnr;
1902  p1 = getPoint2d_cp(l1, pnr1);
1903  if (pnr1+r<0)
1904  {
1905  p01 = getPoint2d_cp(l1, (n1-1));
1906  if (( p1->x == p01->x) && (p1->y == p01->y)) pnr2 = (n1-1);
1907  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*/
1908  }
1909 
1910  else if (pnr1+r>(n1-1))
1911  {
1912  p01 = getPoint2d_cp(l1, 0);
1913  if (( p1->x == p01->x) && (p1->y == p01->y)) pnr2 = 0;
1914  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*/
1915  }
1916  else pnr2 = pnr1+r;
1917 
1918 
1919  p2 = getPoint2d_cp(l1, pnr2);
1920  for (u=0; u<n2; ++u)
1921  {
1922  if (((list2[u].themeasure-list1[i].themeasure)) >= maxmeasure) break;
1923  pnr3 = list2[u].pnr;
1924  p3 = getPoint2d_cp(l2, pnr3);
1925  if (pnr3==0)
1926  {
1927  p02 = getPoint2d_cp(l2, (n2-1));
1928  if (( p3->x == p02->x) && (p3->y == p02->y)) pnr4 = (n2-1);
1929  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*/
1930  }
1931  else pnr4 = pnr3-1;
1932 
1933  p4 = getPoint2d_cp(l2, pnr4);
1934  dl->twisted=twist;
1935  if (!lw_dist2d_selected_seg_seg(p1, p2, p3, p4, dl)) return LW_FALSE;
1936 
1937  if (pnr3>=(n2-1))
1938  {
1939  p02 = getPoint2d_cp(l2, 0);
1940  if (( p3->x == p02->x) && (p3->y == p02->y)) pnr4 = 0;
1941  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*/
1942  }
1943 
1944  else pnr4 = pnr3+1;
1945 
1946  p4 = getPoint2d_cp(l2, pnr4);
1947  dl->twisted=twist; /*we reset the "twist" for each iteration*/
1948  if (!lw_dist2d_selected_seg_seg(p1, p2, p3, p4, dl)) return LW_FALSE;
1949 
1950  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*/
1951  }
1952  }
1953  }
1954 
1955  return LW_TRUE;
1956 }
char * r
Definition: cu_in_wkt.c:25
int npoints
Definition: liblwgeom.h:327
#define LWDEBUG(level, msg)
Definition: lwgeom_log.h:50
double x
Definition: liblwgeom.h:284
#define LW_FALSE
Definition: liblwgeom.h:52
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:458
#define LW_TRUE
Return types for functions with status returns.
Definition: liblwgeom.h:51
double y
Definition: liblwgeom.h:284
int twisted
Definition: measures.h:27
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:1965
double distance
Definition: measures.h:23
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:2087
int pnr
Definition: measures.h:34

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