atan2: Difference between revisions

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{{Command|Comments=
{{Command


| ofp |Game name=
| ofp


|1.00|Game version=
|1.00


|gr1= Math - Geometry |GROUP1=
|gr1= Math - Geometry


| ArcTangent of ''x/y''. Used to determine the angle of a vector ''[x,y]''. Result in [[Number#Degrees|Degrees]] between -180 and 180.
| ArcTangent of ''x/y''. Used to determine the angle of a vector ''[x,y]''. Result in [[Number#Degrees|Degrees]] between -180 and 180.
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{{Informative | This command can handle ''y'' being 0, unlike when using [[atan]], and will return 90 }}
{{Informative | This command can handle ''y'' being 0, unlike when using [[atan]], and will return 90 }}
<br>
<br>
{{Important | Even though this command is a binary operator just like [[select]] command, it has [[SQF_syntax#Rules_of_Precedence | higher precedence]] than [[select]] command, therefore the following expression: <br><tt>_pos select 0 [[atan2]] (_pos select 1)</tt><br> will produce an error. The correct usage in this case will be: <br><tt>(_pos select 0) [[atan2]] (_pos select 1)</tt>}}|DESCRIPTION=
{{Important | Even though this command is a binary operator just like [[select]] command, it has [[SQF_syntax#Rules_of_Precedence | higher precedence]] than [[select]] command, therefore the following expression: <br><tt>_pos select 0 [[atan2]] (_pos select 1)</tt><br> will produce an error. The correct usage in this case will be: <br><tt>(_pos select 0) [[atan2]] (_pos select 1)</tt>}}


| x '''atan2''' y |SYNTAX=
| x '''atan2''' y


|p1=  x: [[Number]] |PARAMETER1=
|p1=  x: [[Number]]


|p2=  y: [[Number]] |PARAMETER2=
|p2=  y: [[Number]]




| [[Number]]  
| [[Number]]  


<br><br>[[Image:atan.jpg|200px]]|RETURNVALUE=
<br><br>[[Image:atan.jpg|200px]]
   
   
|x1= <code>_xy = [5,3];
|x1= <code>_xy = [5,3];
_degrees = (_xy [[select]] 0) [[atan2]] (_xy [[select]] 1); //59.0362</code>|EXAMPLE1=
_degrees = (_xy [[select]] 0) [[atan2]] (_xy [[select]] 1); //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); //_dir range from -180 to +180  
_dir = (_vd [[select]] 0) [[atan2]] (_vd [[select]] 1); //_dir range from -180 to +180  
[[if]] (_dir < 0) [[then]] {_dir = 360 + _dir}; //_dir range from 0 to 360</code>|EXAMPLE2=
[[if]] (_dir < 0) [[then]] {_dir = 360 + _dir}; //_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); //_dir range from -180 to +180  
_dir = (_xy [[select]] 0) [[atan2]] (_xy [[select]] 1); //_dir range from -180 to +180  
[[if]] (_dir < 0) [[then]] {_dir = 360 + _dir}; //_dir range from 0 to 360</code>|EXAMPLE3=
[[if]] (_dir < 0) [[then]] {_dir = 360 + _dir}; //_dir range from 0 to 360</code>






| [[atan]], [[tan]], [[sin]], [[cos]], [[asin]], [[acos]], [[rad]], [[pi]], [[vectorCos]], [[getPos]], [[getRelPos]], [[Math Commands]] |SEEALSO=
| [[atan]], [[tan]], [[sin]], [[cos]], [[asin]], [[acos]], [[rad]], [[pi]], [[vectorCos]], [[getPos]], [[getRelPos]], [[Math Commands]]


}}
}}

Revision as of 00:03, 18 January 2021

Logo A0.png1.00
Hover & click on the images for description

Description

Description:
ArcTangent of x/y. Used to determine the angle of a vector [x,y]. Result in Degrees between -180 and 180.

ⓘ
This command can handle y 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

Syntax

Syntax:
x atan2 y
Parameters:
x: Number
y: Number
Return Value:
Number

atan.jpg

Examples

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 if (_dir < 0) then {_dir = 360 + _dir}; //_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 if (_dir < 0) then {_dir = 360 + _dir}; //_dir range from 0 to 360

Additional Information

See also:
atantansincosasinacosradpivectorCosgetPosgetRelPosMath Commands

Notes

Report bugs on the Feedback Tracker and/or discuss them on the Arma Discord or on the Forums.
Only post proven facts here! Add Note

Notes

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.

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