Determine If Two Points Are Near

Question

I have the following:

bool AreNear(Point Old, Point Current)
{
    int x1 = Convert.ToInt32(Old.X);
    int x2 = Convert.ToInt32(Current.X);
    int y1 = Con         


        

Answer 1

You can use Math.Abs to get the distance:

public static bool InDistance(Point Old, Point Current, int distance)
{
    int diffX = Math.Abs(Old.X - Current.X);
    int diffY = Math.Abs(Old.Y - Current.Y);
    return diffX <= distance && diffY <= distance;
}

use it:

bool arePointsInDistance = InDistance(new Point(100, 120), new Point(120, 99), 25);

Answer 2

Try using the distance formula http://www.purplemath.com/modules/distform.htm and compare the distance <=25

Answer 3

You can use the Pythagorean formula to calculate the distance between two points. In C#:

var d = Math.Sqrt(Math.Pow(x1 - x2, 2) + Math.Pow(y1 - y2, 2)) 

Why does this work? Have a look at the following diagram and remember that a^2 + b^2 = c^2 holds for right triangles:

Answer 4

Just calculate the square of the distance using Pythagoras' theorem, and compare to the square of the radius:

bool ComparePoints(Point Old, Point Current)
{
    int x1 = Convert.ToInt32(Old.X);
    int x2 = Convert.ToInt32(Current.X);
    int y1 = Convert.ToInt32(Old.Y);
    int y2 = Convert.ToInt32(Current.Y);
    int dx = x1 - x2;
    int dy = y1 - y2;
    return (dx*dx + dy*dy) < 25*25;
}