All about Degrees <> Radians

[Yixx]

Heey guys,,

At school i have worked with Cos and Sin with degrees, now i heard here that it is better to use Radians, but how do i use them?
Lets say i got an angle in radians, but i dont know how to increase it the right way,,
So i convert it to degrees, set it + 90 and convert to radians again,,
This is probably way around how it should, so my question is, how to use it well?
What are the basics with Radians?

Thanks! -Yixx,,-

 

[Seth21]

90 degrees= pi/2 rads

 

[Yixx]

Ya ok,, but i dont want it just for 90 degrees, i want to know a general rule for degrees to radians,, not just for 90 degrees,,
Cause i also want to add 45 degrees later, and maybe 2 degrees later on,, you know?

 

[busterkomo]

Use the constant bj_DEGTORAD. It's Pi/180. EG. To convert 90 degrees to radians, it would look something like this:

set r = 90*bj_DEGTORAD

The only real use for bj_DEGTORAD is when dealing with GetUnitFacing, and SetUnitFacing.

Degrees range from 0 to 360, radians range from 0 to around 6.28 (2π).

 

[Yixx]

Ya that would work, but it would become this every time:
set dat.cos = Cos( ( (bj_RADTODEG * dat.a) + 90) * bj_DEGTORAD)

And I dont like that,, so is there an easy way to do it with radians immediately?
something like:
set dat.angle = dat.angle + (Degrees * bj_DEGTORAD)

Would that add the right degrees to it? Would it?

 

[The Reborn Devil]

set dat.cos = Cos(dat.a + 1.5707)

 

[Cov3r70ps]

In a circle, there are 360 degrees and 2*(Pi) radians, meaning that if you want to go from radians to degrees, use a conversion:

X radians = (Your Number of Degrees) * ((2*(PI) radians) / (360 degrees))
X radians = (Your Number of Degrees) * (((PI) radians) / (180 degrees))

Y degrees = (Your Number of Radians) * ((360 degrees) / (2*(PI) radians))
Y degrees = (Your Number of Radians) * ((180 degrees) / ((PI) radians))

I would suggest just doing the calculations by hand before putting them into your scripts, and you'll be able to get the hang of it without too much work.

EDIT: Got my conversions mixed up, should be fixed now.

 

[Yixx]

So,
radians = degrees * PI/180
so if i do:
set NewRadians = OldRadians + (ExtraDegrees * PI/180)

This is the right formula?

Oh, and one more question:
Is there any difference between:
set angle = Cos(a * PI/180)

and

set angle = Cos(a) * PI/180

Any difference?

 

[Cov3r70ps]

So,
radians = degrees * PI/180
so if i do:
set NewRadians = OldRadians + (ExtraDegrees * PI/180)

This is the right formula?

Yes, that should be the right formula.

Oh, and one more question:
Is there any difference between:
set angle = Cos(a * PI/180)

and

set angle = Cos(a) * PI/180

Any difference?

Yeah, there will be a difference between these two pieces of code. You should convert to radians inside of the cosine function, eg.
set angle = Cos(a * PI/180)

Otherwise you will get skewed results.

Hope this helps!

 

[Yixx]

It does! =),, thanks! + rep to youu,,

 

[Cov3r70ps]

It does! =),, thanks! + rep to youu,,

No problem! Just be careful with Degrees and Radians when working with Jass/Triggers (or even worse, a combination of the two), as, if I remember correctly, most triggers use degrees and most native Jass functions use radians (although it is not always the case).

 

[Yixx]

Ya, SetUnitFacing(), GetUnitFacing() and some more use/return degrees, but most functions/natives use radians,, i heard,,

 

[GhostWolf]

I don't think there is any programming language that takes or returns degrees in any trigo function.

 

[Cov3r70ps]

I don't think there is any programming language that takes or returns degrees in any trigo function.

I didn't mean the base trig functions like cosine, sine, or tangent, but there are some other functions that utilize angles that can get confusing.

 

[PurplePoot]

The mathematics are done in radians (because degrees suck) and thus the programming languages all use radians.

 

[Cov3r70ps]

The mathematics are done in radians (because degrees suck) and thus the programming languages all use radians.

I couldn't agree more.

 

[The Reborn Devil]

Radians can also be harder to handle than degrees for some people and that's why I think Blizzard made some of the functions use degrees or added BJ versions of those natives that used radians to help people that have problems with it.