Finding the distance between two mobiles

[vermillion2083]

Good afternoon all,

The distance between two mobiles has been a value that I have found myself needing several times in the past, so I figured its due time I figured it out. I made an attempt using the Pythagorean Theorem but I am not entirely sure if this will function or not (I am at work so I am unable to test it). I've seen several users show their amazing capabilities with mathematic formulas here on the RunUO forums, so I figured I would post my first attempt in hopes that someone will be able to either confirm that this method will function, or lead me in a better direction.

	public static int CalculateDistance( Mobile from, Mobile target )
	{
		int distance = Math.Sqrt( Math.Pow( from.X - from.Y, 2 ) + Math.Pow( target.X - target.Y, 2 ) );
		return distance;
	}

The formula I was attempting to follow (although it has been so long since I’ve taken a math class only god know how far off I am) can be found here:

The Distance Formula

Any assistance with this method would be greatly appreciated. Thank you all in advance!

[mordero]

Almost, but not quite. Its:

    public static int CalculateDistance( Mobile from, Mobile target )
    {
        int distance = Math.Sqrt( Math.Pow( from.X - target.X, 2 ) + Math.Pow( from.Y - target.Y, 2 ) );
        return distance;
    }

[vermillion2083]

Ahh *smacks his head*, thanks for the catch. It's good to know it's this simple, thanks a million mordero. I'm excited to get home and fiddle around with this and see what I can do with it.

[arul]

You can use the api:

double distance = mobile1.GetDistanceToSqrt(mobile2);

Anyway, if you want to compare the distance against some fixed value, rather use a power-of-two of the fixed value since square root calculations are quite expensive.

So if the original code looked like:

    public static int CalculateDistance( Mobile from, Mobile target )
    {
        int distance = Math.Sqrt( Math.Pow( from.X - target.X, 2 ) + Math.Pow( from.Y - target.Y, 2 ) );
        return distance;
    }
....
   if(CalculateDistance( m1, m2 ) > 7)
  {
     DoSomething();
  }

Then the optimized code would look like:

public static int CalculateDistanceSansSqrt(Mobile from, Mobile target)
{
     int dx= from.X - target.X;
     int dy= from.Y - target.Y;

     return (dx*dx) + (dy*dy);
}

   if(CalculateDistanceSansSqrt( m1, m2 ) > ( 7*7 )/*49*/)
  {
     DoSomething();
  }

Without the square root it turns out to be like 3.5 times faster.

[vermillion2083]

Terrific information arul, thank you for the input.