ST_ANGLE

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

mysql> SELECT ST_Angle(ST_Point(1, 0),ST_Point(0, 0),ST_Point(0, 1));
+----------------------------------------------------------------------+
| st_angle(st_point(1.0, 0.0), st_point(0.0, 0.0), st_point(0.0, 1.0)) |
+----------------------------------------------------------------------+
|                                                     4.71238898038469 |
+----------------------------------------------------------------------+
1 row in set (0.04 sec)

mysql> SELECT ST_Angle(ST_Point(0, 0),ST_Point(1, 0),ST_Point(0, 1));
+----------------------------------------------------------------------+
| st_angle(st_point(0.0, 0.0), st_point(1.0, 0.0), st_point(0.0, 1.0)) |
+----------------------------------------------------------------------+
|                                                  0.78547432161873854 |
+----------------------------------------------------------------------+
1 row in set (0.02 sec)

mysql> SELECT ST_Angle(ST_Point(1, 0),ST_Point(0, 0),ST_Point(1, 0));
+----------------------------------------------------------------------+
| st_angle(st_point(1.0, 0.0), st_point(0.0, 0.0), st_point(1.0, 0.0)) |
+----------------------------------------------------------------------+
|                                                                    0 |
+----------------------------------------------------------------------+
1 row in set (0.02 sec)

mysql> SELECT ST_Angle(ST_Point(1, 0),ST_Point(0, 0),ST_Point(0, 0));
+----------------------------------------------------------------------+
| st_angle(st_point(1.0, 0.0), st_point(0.0, 0.0), st_point(0.0, 0.0)) |
+----------------------------------------------------------------------+
|                                                                 NULL |
+----------------------------------------------------------------------+
1 row in set (0.03 sec)

mysql> SELECT ST_Angle(ST_Point(0, 0),ST_Point(-30, 0),ST_Point(150, 0));
+--------------------------------------------------------------------------+
| st_angle(st_point(0.0, 0.0), st_point(-30.0, 0.0), st_point(150.0, 0.0)) |
+--------------------------------------------------------------------------+
|                                                                     NULL |
+--------------------------------------------------------------------------+
1 row in set (0.02 sec)

keywords

ST_ANGLE,ST,ANGLE