PostGIS  2.5.1dev-r@@SVN_REVISION@@

◆ azimuth_pt_pt()

int azimuth_pt_pt ( const POINT2D A,
const POINT2D B,
double *  d 
)

Compute the azimuth of segment AB in radians.

Return 0 on exception (same point), 1 otherwise.

Definition at line 2416 of file measures.c.

References POINT2D::x, and POINT2D::y.

Referenced by _lwt_AddEdge(), _lwt_FindAdjacentEdges(), _lwt_InitEdgeEndByLine(), LWGEOM_angle(), and LWGEOM_azimuth().

2417 {
2418  if ( A->x == B->x )
2419  {
2420  if ( A->y < B->y ) *d=0.0;
2421  else if ( A->y > B->y ) *d=M_PI;
2422  else return 0;
2423  return 1;
2424  }
2425 
2426  if ( A->y == B->y )
2427  {
2428  if ( A->x < B->x ) *d=M_PI/2;
2429  else if ( A->x > B->x ) *d=M_PI+(M_PI/2);
2430  else return 0;
2431  return 1;
2432  }
2433 
2434  if ( A->x < B->x )
2435  {
2436  if ( A->y < B->y )
2437  {
2438  *d=atan(fabs(A->x - B->x) / fabs(A->y - B->y) );
2439  }
2440  else /* ( A->y > B->y ) - equality case handled above */
2441  {
2442  *d=atan(fabs(A->y - B->y) / fabs(A->x - B->x) )
2443  + (M_PI/2);
2444  }
2445  }
2446 
2447  else /* ( A->x > B->x ) - equality case handled above */
2448  {
2449  if ( A->y > B->y )
2450  {
2451  *d=atan(fabs(A->x - B->x) / fabs(A->y - B->y) )
2452  + M_PI;
2453  }
2454  else /* ( A->y < B->y ) - equality case handled above */
2455  {
2456  *d=atan(fabs(A->y - B->y) / fabs(A->x - B->x) )
2457  + (M_PI+(M_PI/2));
2458  }
2459  }
2460 
2461  return 1;
2462 }
double x
Definition: liblwgeom.h:330
double y
Definition: liblwgeom.h:330
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