PostGIS  2.3.8dev-r@@SVN_REVISION@@

◆ distance2d_sqr_pt_seg()

double distance2d_sqr_pt_seg ( const POINT2D p,
const POINT2D A,
const POINT2D B 
)

Definition at line 2389 of file measures.c.

References distance2d_sqr_pt_pt(), r, s, POINT2D::x, and POINT2D::y.

Referenced by ptarray_dp_findsplit().

2390 {
2391  double r,s;
2392 
2393  if ( ( A->x == B->x) && (A->y == B->y) )
2394  return distance2d_sqr_pt_pt(p,A);
2395 
2396  r = ( (p->x-A->x) * (B->x-A->x) + (p->y-A->y) * (B->y-A->y) )/( (B->x-A->x)*(B->x-A->x) +(B->y-A->y)*(B->y-A->y) );
2397 
2398  if (r<0) return distance2d_sqr_pt_pt(p,A);
2399  if (r>1) return distance2d_sqr_pt_pt(p,B);
2400 
2401 
2402  /*
2403  * (2)
2404  * (Ay-Cy)(Bx-Ax)-(Ax-Cx)(By-Ay)
2405  * s = -----------------------------
2406  * L^2
2407  *
2408  * Then the distance from C to P = |s|*L.
2409  *
2410  */
2411 
2412  s = ( (A->y-p->y)*(B->x-A->x)- (A->x-p->x)*(B->y-A->y) ) /
2413  ( (B->x-A->x)*(B->x-A->x) +(B->y-A->y)*(B->y-A->y) );
2414 
2415  return s * s * ( (B->x-A->x)*(B->x-A->x) + (B->y-A->y)*(B->y-A->y) );
2416 }
double distance2d_sqr_pt_pt(const POINT2D *p1, const POINT2D *p2)
Definition: measures.c:2325
char * r
Definition: cu_in_wkt.c:24
double x
Definition: liblwgeom.h:327
double y
Definition: liblwgeom.h:327
char * s
Definition: cu_in_wkt.c:23
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