atan2: Difference between revisions

Revision as of 21:52, 7 May 2022

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Description:: ArcTangent of y/x. Used to determine the angle of a vector [x,y]. Result in Degrees between -180 and 180.
ⓘ
This command can handle x being 0, unlike when using atan, and will return 90

⚠
Even though this command is a binary operator just like select command, it has higher precedence than select command, therefore the following expression:
_pos select 0 atan2 (_pos select 1)
will produce an error. The correct usage in this case will be:
(_pos select 0) atan2 (_pos select 1)
Groups:: Math - Geometry

Example 1:: _xy = [5,3]; _degrees = (_xy select 0) atan2 (_xy select 1); // 59.0362
Example 2:: Get direction from _obj1 to _obj2: _vd = getPosASL _obj2 vectorDiff getPosASL _obj1; _dir = (_vd select 0) atan2 (_vd select 1); // _dir range from -180 to +180 _dir = (_dir + 360) % 360; // _dir range from 0 to 360
Example 3:: Get relative direction from _obj1 to _obj2: _xy = _obj1 worldToModel getPosASL _obj2; _dir = (_xy select 0) atan2 (_xy select 1); // _dir range from -180 to +180 _dir = (_dir + 360) % 360; // _dir range from 0 to 360

See also:: atan tan sin cos asin acos rad pi vectorCos getPos getRelPos Math Commands

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Only post proven facts here! Add Note

: Posted on 08:00, 18 November 2009
KeV: To get the direction of an object from the player: _dir = ((getPos _obj select 0) - (getPos player select 0)) atan2 ((getPos _obj select 1) - (getPos player select 1)); //_dir will be from -180 to 180. If positive values are needed then use: if (_dir < 0) then {_dir = _dir + 360}; Or just use BIS_fnc_dirTo directly.

@@ Line 39: / Line 39: @@
 _degrees = (_xy [[select]] 0) [[atan2]] (_xy [[select]] 1); {{cc|59.0362}}</code>
-|x2= Get direction from _obj1 to _obj2:<code>_vd = [[getPosASL]] _obj2 [[vectorDiff]] [[getPosASL]] _obj1;
+|x2= Get direction from _obj1 to _obj2:
+<code>_vd = [[getPosASL]] _obj2 [[vectorDiff]] [[getPosASL]] _obj1;
 _dir = (_vd [[select]] 0) [[atan2]] (_vd [[select]] 1); {{cc|_dir range from -180 to +180}}
 _dir = (_dir + 360) % 360; {{cc|_dir range from 0 to 360}}</code>
-|x3= Get relative direction from _obj1 to _obj2:<code>_xy = _obj1 [[worldToModel]] [[getPosASL]] _obj2;
+|x3= Get relative direction from _obj1 to _obj2:
+<code>_xy = _obj1 [[worldToModel]] [[getPosASL]] _obj2;
 _dir = (_xy [[select]] 0) [[atan2]] (_xy [[select]] 1); {{cc|_dir range from -180 to +180}}
 _dir = (_dir + 360) % 360; {{cc|_dir range from 0 to 360}}</code>