Get_Angle()

ID:169218
 
Jul 19 2005, 1:14 am
I've been trying to write a procedure for getting the angle from point A to point B, but I haven't been able to find any decent tutorials/formulas/graphs on the web. Well, I did find one but I had accidently closed it and could not find it again. So if anyone would teach me right-angle trigonometry it'd be great. :-)

Oh, and from what I interpreted, I came up with the three sides and their length:
proc/get_angle(atom/A,atom/B)
    var {X=abs(A.x-B.x);Y=abs(A.y-B.y)}
    var/Hypotenuse=round(sqrt((X*X)+(Y*Y)))
    var/Adjacent=X
    var/Opposite=Y


Is that correct?
Jul 19 2005, 1:58 am
Yes, that looks about right. To get the angle you're going to need to use arccos() or arcsin(). I'll use arcsin()

The sin of an angle is the value of the opposite/hypontenuse

Arcsin is the opposite function of sin. So you would do...

return arcsin(Opposite/Hypotenuse)

I think that should do it. I've only learned basic trig so far.
Jul 19 2005, 2:01 am
In response to Dark Weasel
So arcsin(o/h) would return my angle? Thanks. :-)
Jul 19 2005, 2:04 am
In response to Crashed
Yeah that sounds like what I used to use when calculating the turn points for my units in the old Battle System add on for AD&D, back when I used to play.
Jul 19 2005, 2:07 am
In response to Crashed
I just tried, and it nearly works. I had edited atom/Click() to show the angle get_angle returns, when I click at the top of the screen in a straight line infront of me it'll return 90 (which is good), and in a straight line to the right it returns 0 (good), but when I click at the top right corner, it should return 45 degrees but instead it returns 48.5904. What would be my problem?

Edit: Actually, this isn't working properly. I'll click on an area that should equal to about 80ish degrees but it's still 90, and I'll click on a tile over that one and it's still 90. For about 4 tiles it'll still return 90 degrees.
Jul 19 2005, 2:48 am (Edited on Jul 19 2005, 3:03 am)
In response to Crashed
Take out the round(). You can add a round() when you display the angle, if you don't want decimals.
If you compared 1,1 and 2,2, you'd come out with 2.236 as a hypotenuse. Then you'd divide 2 by it, which'd give you .894. You'll get an angle of 63.438 when arcsin()ing that, but if you rounded the hypotenuse to 2, you'd come out with 1, and you'd get a 90 degree angle when arcsin()ing it.