get_ procs

Jan 31 2013, 5:59 pm
Bravo1	The code's pretty much the same, yours is more compact though. I'm crap with formatting.

Jan 31 2013, 6:07 pm

Bravo1

It's probably because BYOND uses a truncated version of Pi.

Magnun2k's is pretty much the same, but highers factors of Pi.

His is more accurate, but a bit slower as a result.

Or at least that's what it seems to be.

I'm gonna be updating the library soon to include get_angle_nums() which is the same as get_angle() but you can use four numeric values instead of atoms, in case you prefer that.

Ultimately I'll cut the proc down to be universal and take any kind of entry. Ex: (num,num,atom)/(atom,num,num)/(atom,atom)/(num,num,num,num)

But I'm lazy so that'll come later XD

Jan 31 2013, 6:08 pm
Magnum2k	Actually, I made a mistake. Forget the 180 / PI since Lummox's atan2() returns an angle in degrees.

Jan 31 2013, 6:12 pm
Bravo1	Do they return the same results?

Jan 31 2013, 6:14 pm
Bravo1	Also I think mine would be a bit faster without the call for round() and the checks to make sure the returned angle is between 0 and 360. I figured I'd include that stuff for the sake or convenience.

Jan 31 2013, 6:20 pm
Magnum2k	Weird.

Jan 31 2013, 6:24 pm
Bravo1	Give a few examples of what they return. It could be the same angle but in a different format.. Ex: 345 degrees = -15 degrees

Jan 31 2013, 6:25 pm

Magnum2k

Another re-vamped version.

proc

    //  Credit to Lummox JR for the atan2()
    fatan2(x, y)
        if(!x && !y)
            return 0
        . = arccos(x / sqrt(x * x + y * y))
        return y >= 0 ? . : -.

    fget_angle(atom/a, atom/b)
        return fatan2(b.y - a.y, b.x - a.x)

Jan 31 2013, 7:29 pm

FIREking

Ok, I got some more implementations, and all of them are returning the same values (I prefer North to be 0, South to be 180, East to be 90, and West to be 270).

Here's code and results:

proc

    //  Credit to Lummox JR for the atan2()
    atan2(x, y)
        if(!(x || y))
            return 0
        . = arccos(x / sqrt(x * x + y * y))
        return y >= 0 ? . : -.
        
    more_mem_get_angle(atom/a, atom/b)
        var/dx = b.x - a.x
        var/dy = b.y - a.y
        var/val = sqrt(dx * dx + dy * dy)
        if(!val) return 0
        var/ar = arccos(dx / val)
        var/deg = round(360 - (dy >= 0 ? ar : -ar), 1)
        deg -= 270
        while(deg > 360) deg -= 360
        while(deg < 0) deg += 360
        return deg
        
    get_angle(atom/a, atom/b)
        var/val = sqrt((b.x - a.x) * (b.x - a.x) + (b.y - a.y) * (b.y - a.y))
        if(!val) return 0
        var/ar = arccos((b.x - a.x) / val)
        var/deg = round(360 - (b.y - a.y >= 0 ? ar : -ar), 1)
        deg -= 270
        while(deg > 360) deg -= 360
        while(deg < 0) deg += 360
        return deg
        
    other_get_angle(atom/a, atom/b)
        var/res = atan2(b.y - a.y, b.x - a.x)
        while(res > 360) res -= 360
        while(res < 0) res += 360
        return res
        
mob
    verb/test()
        for(var/n = 1 to 10)
            for(var/nn = 1 to 1000)
                var/obj/a = new(locate(rand(1,64), rand(1, 64), 1))
                var/obj/b = new(locate(rand(1,64), rand(1, 64), 1))
                world << "get_angle returns [get_angle(a, b)]"
                world << "other_get_angle returns [other_get_angle(a, b)]"
                world << "more_mem_get_angle returns [more_mem_get_angle(a, b)]"

Feb 1 2013, 12:58 am
Bravo1	Ok, I got some more implementations, and all of them are returning the same values (I prefer North to be 0, South to be 180, East to be 90, and West to be 270). Unfortunately BYOND and trigonometry doesn't like that. You'll be making a -270 adjustment to every input. shrugs If that's how you prefer it though...

Feb 1 2013, 1:44 am In response to Bravo1
FIREking	Bravo1 wrote: Ok, I got some more implementations, and all of them are returning the same values (I prefer North to be 0, South to be 180, East to be 90, and West to be 270). Unfortunately BYOND and trigonometry doesn't like that. You'll be making a -270 adjustment to every input. shrugs If that's how you prefer it though... Yeah, which isn't a big deal.

Feb 1 2013, 5:57 am

Magnum2k

You can also optimize Lummox's algorithm a bit further. I did some testing and the snippet below is a bit faster, though the speed increase is negligible.

proc
    
    //  Original atan2() by Lummox R
    atan2(x, y)
        if(!x && !y)
            return 0
        . = arccos(x / sqrt(x * x + y * y))
        return y >= 0 ? . : -.
    
    //  Modified atan2() by Magnum2k
    atan3(x, y)
        if(isnull(x || y))
            return 0
        return y >= 0 ? arccos(x / sqrt(x * x + y * y)) : \
                       -arccos(x / sqrt(x * x + y * y))

Result:

EDIT: Lummox JR's atan2() seems to get more exhausted as more calls are made to it.

Feb 1 2013, 6:19 am
Bravo1	It doesn't look like atan3 is getting called in that profile. o_o

Feb 1 2013, 6:24 am
Magnum2k	It is. I forgot to change the name in the snippet. Haha.

Dec 16 2013, 5:43 am
Turboskill	so atan3 would be f_atan2?

	get_ procs by Bravo1
	A helpful set of procs for angular and positional data!