PostGIS  2.5.0dev-r@@SVN_REVISION@@
double distance2d_sqr_pt_seg ( const POINT2D p,
const POINT2D A,
const POINT2D B 
)

Definition at line 2386 of file measures.c.

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

Referenced by ptarray_dp_findsplit_in_place().

2387 {
2388  double r,s;
2389 
2390  if ( ( A->x == B->x) && (A->y == B->y) )
2391  return distance2d_sqr_pt_pt(p,A);
2392 
2393  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) );
2394 
2395  if (r<0) return distance2d_sqr_pt_pt(p,A);
2396  if (r>1) return distance2d_sqr_pt_pt(p,B);
2397 
2398 
2399  /*
2400  * (2)
2401  * (Ay-Cy)(Bx-Ax)-(Ax-Cx)(By-Ay)
2402  * s = -----------------------------
2403  * L^2
2404  *
2405  * Then the distance from C to P = |s|*L.
2406  *
2407  */
2408 
2409  s = ( (A->y-p->y)*(B->x-A->x)- (A->x-p->x)*(B->y-A->y) ) /
2410  ( (B->x-A->x)*(B->x-A->x) +(B->y-A->y)*(B->y-A->y) );
2411 
2412  return s * s * ( (B->x-A->x)*(B->x-A->x) + (B->y-A->y)*(B->y-A->y) );
2413 }
double distance2d_sqr_pt_pt(const POINT2D *p1, const POINT2D *p2)
Definition: measures.c:2322
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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