ST_Angle

Syntax

DOUBLE ST_Angle(GEOPOINT point1, GEOPOINT point2, GEOPOINT point3)

description

Enter three point, which represent two intersecting lines. Returns the angle between these lines. Point 2 and point 1 represent the first line and point 2 and point 3 represent the second line. The angle between these lines is in radians, in the range [0, 2pi). The angle is measured clockwise from the first line to the second line.

ST_ANGLE has the following edge cases:

  • If points 2 and 3 are the same, returns NULL.
  • If points 2 and 1 are the same, returns NULL.
  • If points 2 and 3 are exactly antipodal, returns NULL.
  • If points 2 and 1 are exactly antipodal, returns NULL.
  • If any of the input geographies are not single points or are the empty geography, then throws an error.

example

  1. mysql> SELECT ST_Angle(ST_Point(1, 0),ST_Point(0, 0),ST_Point(0, 1));
  2. +----------------------------------------------------------------------+
  3. | st_angle(st_point(1.0, 0.0), st_point(0.0, 0.0), st_point(0.0, 1.0)) |
  4. +----------------------------------------------------------------------+
  5. |                                                     4.71238898038469 |
  6. +----------------------------------------------------------------------+
  7. 1 row in set (0.04 sec)
  9. mysql> SELECT ST_Angle(ST_Point(0, 0),ST_Point(1, 0),ST_Point(0, 1));
  10. +----------------------------------------------------------------------+
  11. | st_angle(st_point(0.0, 0.0), st_point(1.0, 0.0), st_point(0.0, 1.0)) |
  12. +----------------------------------------------------------------------+
  13. |                                                  0.78547432161873854 |
  14. +----------------------------------------------------------------------+
  15. 1 row in set (0.02 sec)
  17. mysql> SELECT ST_Angle(ST_Point(1, 0),ST_Point(0, 0),ST_Point(1, 0));
  18. +----------------------------------------------------------------------+
  19. | st_angle(st_point(1.0, 0.0), st_point(0.0, 0.0), st_point(1.0, 0.0)) |
  20. +----------------------------------------------------------------------+
  21. |                                                                    0 |
  22. +----------------------------------------------------------------------+
  23. 1 row in set (0.02 sec)
  25. mysql> SELECT ST_Angle(ST_Point(1, 0),ST_Point(0, 0),ST_Point(0, 0));
  26. +----------------------------------------------------------------------+
  27. | st_angle(st_point(1.0, 0.0), st_point(0.0, 0.0), st_point(0.0, 0.0)) |
  28. +----------------------------------------------------------------------+
  29. |                                                                 NULL |
  30. +----------------------------------------------------------------------+
  31. 1 row in set (0.03 sec)
  33. mysql> SELECT ST_Angle(ST_Point(0, 0),ST_Point(-30, 0),ST_Point(150, 0));
  34. +--------------------------------------------------------------------------+
  35. | st_angle(st_point(0.0, 0.0), st_point(-30.0, 0.0), st_point(150.0, 0.0)) |
  36. +--------------------------------------------------------------------------+
  37. |                                                                     NULL |
  38. +--------------------------------------------------------------------------+
  39. 1 row in set (0.02 sec)

keywords

ST_ANGLE,ST,ANGLE