PostGIS  2.2.8dev-r@@SVN_REVISION@@

◆ distance2d_sqr_pt_seg()

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

Definition at line 2376 of file measures.c.

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

Referenced by ptarray_dp_findsplit().

2377 {
2378  double r,s;
2379 
2380  if ( ( A->x == B->x) && (A->y == B->y) )
2381  return distance2d_sqr_pt_pt(p,A);
2382 
2383  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) );
2384 
2385  if (r<0) return distance2d_sqr_pt_pt(p,A);
2386  if (r>1) return distance2d_sqr_pt_pt(p,B);
2387 
2388 
2389  /*
2390  * (2)
2391  * (Ay-Cy)(Bx-Ax)-(Ax-Cx)(By-Ay)
2392  * s = -----------------------------
2393  * L^2
2394  *
2395  * Then the distance from C to P = |s|*L.
2396  *
2397  */
2398 
2399  s = ( (A->y-p->y)*(B->x-A->x)- (A->x-p->x)*(B->y-A->y) ) /
2400  ( (B->x-A->x)*(B->x-A->x) +(B->y-A->y)*(B->y-A->y) );
2401 
2402  return s * s * ( (B->x-A->x)*(B->x-A->x) + (B->y-A->y)*(B->y-A->y) );
2403 }
double distance2d_sqr_pt_pt(const POINT2D *p1, const POINT2D *p2)
Definition: measures.c:2312
char * r
Definition: cu_in_wkt.c:24
double x
Definition: liblwgeom.h:312
double y
Definition: liblwgeom.h:312
char * s
Definition: cu_in_wkt.c:23
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