LFS Forum - How to add a xy circle area ?

(9 posts, started Sat, 6 Dec 2008 14:39)

#1 - Marco1

How to add a xy circle area ?

Sat, 6 Dec 2008 14:39

Hello Programmers,

Im working on a Sumo system and needs help with code for a xy circle
if im in the circle its all ok but if im driving out of it it will specs me.

Ive tryed every combinations from codes but nothing is the right one.

===========================================
My Setups:

Language: C#
Database: MySql
Microsoft Visual C# 2008 Express Version SP1
Libary: LFS_External 1.1.1.4
===========================================

#2 - AndroidXP

Sat, 6 Dec 2008 15:06

Why do so many people fail on the simplest of problems? *sigh* Oh well...

Ever heard of a² + b² = c² ? You can easily calculate the distance between two points in a X/Y coordinate system by calculating dist = sqrt(Xdist² + Ydist²), where Xdist = Xcirle - Xcar and Ydist = Ycircle - Ycar. With this distance you then only need to check if it's shorter or longer than the circle's radius to determine whether the car is inside the circle or outside.

Just make yourself a Circle class like this...


public class Circle
{
    private double x, y, r;

    public Circle(double x, double y, double r)
    {
        this.x = x;
        this.y = y;
        this.r = r;
    }

    public bool Contains(double carX, double carY)
    {
        return Math.Sqrt(Math.Pow(x - carX, 2) + Math.Pow(y - carY, 2)) <= r;
    }
}

Then somewhere you define your sumo area and do your checks as required...


Circle sumoArea = new Circle(0, 0, 15 * 65535); //Right in the middle of the map (x=0, y=0) with 15 metres radius
...
if (!sumoArea.Contains(car.X, car.Y))
{ //you lose! }

I haven't tested it, but you get the idea. You can also incorporate automatic conversion of LFS units to metres to make the defining of circle areas a bit more intuitive.

#3 - Marco1

Sat, 6 Dec 2008 15:26

hey thnks for this fast replay you must know i have started coding for 2weeks ^^ but i will learn realy hard that i can code better and faster

#4 - AndroidXP

Sat, 6 Dec 2008 18:45

Yeah sorry, I didn't want to discourage you or anything. Everybody starts as a newbie at some point I guess...

#5 - Marco1

Sat, 6 Dec 2008 19:05