ST_ANGLE

Description

Enter three points that represent two intersecting lines. Return the Angle between these lines.

Syntax

ST_ANGLE( <point1>, <point2>, <point3>)

Parameters

Parameters	Instructions
<point1>	The first point of the first line
<point2>	The second point of the first line and the first point of the second line
<point3>	The second point of the second line

Return Value

The Angle between these lines is expressed in radians and ranges from [0, 2pi]. The Angle is measured clockwise from the first line to the second line.

ST_ANGLE has the following edge cases:

• If point 2 and point 3 are the same, NULL is returned
• If point 2 and point 1 are the same, NULL is returned
• NULL is returned if points 2 and 3 are perfect Antipodes
• NULL is returned if points 2 and 1 are perfect AntipodesL
• If any input geography is not a single point or is an empty geography, an error is thrown

Examples

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 |
+----------------------------------------------------------------------+

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 |
+----------------------------------------------------------------------+

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 |
+----------------------------------------------------------------------+

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 |
+----------------------------------------------------------------------+

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 |
+--------------------------------------------------------------------------+