finding an angle between two points

I'm working on an AI for an enemy, but there are some math bits that I do not know how to execute.

I need to find the angle between the enemy and the player, so that I can attack the player (or rather where the player is at that exact moment.)
I only need the angle in 2D space, and the code I am using to accelerate to the player's location requires the angle in radians. It's easy to convert degrees to radians, but either way, I'd need an angle between two points in X and Y.

How do I calculate that angle?

 

http://docs.unity3d.com/ScriptReference/Vector2.Angle.html

Vector2.Angle does the math for you!

 

I think Mathf.Atan2 is going to be more in line with what you need than Vector2.Angle, given that V2.Angle will only ever give a positive number between 0 and 180 (it's the difference between two direction vectors) with no indication of which direction the vector is rotating. Atan2, on the other hand, gives you a full 360 degree exact angle - or rather, it gives you a full 6.28 exact angle, because conveniently enough (for you), it returns the result in radians!

 

But Atan2 requires two floats, and I have two positions.

 

You use y2-y1 and x2-x1.

 

Okay! It's working now, thanks!

Vector2.angle was making it fly off in the same direction every time.

 

Been struggling with the same thing, just want to say that this was the solution for me, thanks.

 

simple, use this

Vector2 Point_1 = new Vector2([pos_x],[pos_y]);
Vector2 Point_2 = new Vector2([pos_x],[pos_y]);
float angle = Mathf.Atan2(Point_2.y - Point_1.y , Point_2.x-Point_1.x) * 180 / Mathf.PI;

Good Luck

 

Or you could replace the * 180 / Mathf.PI with a simpler * mathf.Rad2Deg.

@MelvMay that Vector2.Angle simply never works right; it never gives me a proper angle in degrees. I don't know what is wrong with it. The Atan2 method is the only thing I can get tow work right.
Side note, that avatar is the greatest I have ever seen.

 

It's simply because there is no such thing as an angle between two points. You can only have an angle between two lines and those require 3 points. Vector2.Angle calculates the angle at the origin between the two lines from the origin to each of the two points. Such points are actually known as vectors. All vectors have their tail sitting at the origin.

You don't want the angle between two points as seen from the origin, you want the angle of the line between your two points to some reference line. That reference line is mathematically usually the x axis. That's what Atan2 is actually calculating because angles in math start with 0° at the x axis. So to get the angle of the line between your two points in reference to the x-axis you could do:

Code (CSharp):

1. float angle = Vector2.Angle(p2 - p1, Vector2.right);

or if you need a signed angle you can use Vector2.SignedAngle in the same way:

Code (CSharp):

1. float angle = Vector2.SignedAngle(p2 - p1, Vector2.right);

If you have trouble understanding the concept of vectors vs points (points are just vectors from the origin),I can generally recommend the 3B1B series on linear algebra. If you have trouble with trigonometry and how to apply vector math to specific game development issues, I can recommend Freya Holmer's series Math for Game Devs. Those are quite verbose videos, so watch them if you really want to learn how it works. Yes, it takes some time but game dev requires a lot of math and you should get comfortable with it, at least with the basic stuff.

 

Today is a good day to smile!

 

Great thread: suddenly the wonderful world of vectors starts to make sense!