get heading from 2D coordinates.

[chrishind10]

I have a bit of a problem, I need to turn X and Y coordinates into an angle fron the centre of a shape. I have a 10 by 10 grid, and I am detecting presses, I need to work out the angle those presses are at relative to the center of the grid.
[IMG]http://i205.photobucket.com/albums/bb139/chrishind10/diagram-1.jpg[/IMG]
So basicly I want to convert X and Y coordinates into a heading. A formula to do this would be brilliant (sorry for the bad diagram and possibly bad explination)

[dingusnin]

like a local vector 2 get to it

[editline]12:52PM[/editline]

?

[chrishind10]

Yes, exactly!

[editline]12:54PM[/editline]

I just need an algebra formula, that would be perfect.

[Ananace]

If I remember correctly then you can use atan to get the angular heading from a set of (normalized) coordinates,

I think it was something like

double ang = atan2(x, -y);

[dingusnin]

in 3d angles , i would do this

local header = destination - Player.Getpos()

or somthing like that , its one way or the other , it works in wire , i know that

[ColdFusion]

use sin, cos, tan ([url]http://en.wikipedia.org/wiki/Trigonometric_functions[/url])

[url]http://www.cplusplus.com/reference/clibrary/cmath/atan/[/url]

[cpp]
double ang = atan(Y/X);
[/cpp]
Yea its also possible to use atan2 its the same thing

[cpp]sqrt(pow(X,2) + pow(Y,2))[/cpp] The lenght
[cpp]ang * 180 / PI[/cpp] converts rad to deg

Everything should be done using normalized vectors.

[esalaka]

[QUOTE=ColdFusion;25037465]Yea its also possible to use atan2 its the same thing[/QUOTE]

Actually you want to use atan2 and not atan, because atan doesn't give the correct angle for each quadrant.

[deloc]

[QUOTE=ColdFusion;25037465]Yea its also possible to use atan2 its the same thing.[/QUOTE]

wrooooooooooooooooooooooong.
[IMG]http://imgur.com/cLRzQ.png[/IMG]

[thomasfn]

[img]http://www.fortfn.co.uk/images/angle1.png[/img]

Classic GCSE math question.

[editline]09:33PM[/editline]

Assuming x is right, and y is up.

[Robber]

[QUOTE=ace13;25037341]If I remember correctly then you can use atan to get the angular heading from a set of (normalized) coordinates,

I think it was something like

double ang = atan2(x, -y);

[/QUOTE]
I'm pretty sure the first parameter for atan2 is usually y.

[chrishind10]

Thanks for the help, I have my C in Maths (Not my strong point), so I dropped it and moved onto Graphics...