Getting Degree's of where you are to a players Radius

[SwInY]

Hey Guys,

i have a really technical maths question. and due the fact i hate maths. im asking you guys lol.

What im trying to get is,

my Degree's or radian of where my location is, compared to a other person.



Basiclly its the "guts" out of IsBehind, exept the bool is a output.

ANY help!?

[xalcon]

Well, I don't know if can get this right, but I will try.

First you have to calculate the distance on x and y (or z) axes, to get the necessary values for a (arc-)tangens calculation
DiffX = EnemyPosX - YourPosX
DiffY = EnemyPosY - YourPosY (Or Z, depending on your point of view)

Rule: tan(alpha) = X / Y and tan(beta) = Y / X

MeToEnemyDegrees_Absolute = tan^-1 * (DiffX / DiffY)
or
EnemyToMeDegrees_Absolute = tan^-1 * (DiffY / DiffX)

To determine if something is behind someone/something, you can do the folllowing: (Not tested)

public bool IsBehind(GameObject obj)
{
	double x = obj.x - this.x;
	double y = obj.y - this.y;
	double d = Math.Atan() * (y / x); // Absolute rotation "Object to Object"
					  // If you set your rotation to this value, you will face the object
					
	double r = d - this.RotationZ; 	  // substracting object rotation from absolute rotation
	
	if(Math.Abs(r) > 180) r = (Math.Abs(r) - 360) * -1;
	return (r > 90);		  // If the relative rotation to the object is bigger than 90 degrees,
					  // the given object is behind "this"
}

[SwInY]

Thanks for that, got it working.

        public static double GetStandingDegrees
        {
            get
            {
                double d = Math.Atan2((Target.Y - Me.Y), (Target.X - Me.X));

                double r = d - Target.Rotation; 	  // substracting object rotation from absolute rotation
                if (r < 0)
                    r += (Math.PI * 2);

                return r;
            }            
        }