Collision detection between a circle and rectangle

Hi,
I need to implement collision detection algorithm for the small game I'm developing. The objects i have here is ball/circle and a rectangle. The balls are moving vertically, while the rectangle is moving horizontally. The condition is that if the ball and rectangle touch each other then an event should be raised. I have been trying to do that for a while without success. This is my first program in C# so please bear with me.

Here is my code for the two objects that i want to check their collision

Code:

---

class Ball
    {       
        public float x, y, yvel, radius;
        public Brush brush;
        public Ball(int gamewidth,int gameHeight,Random r)
        {
         
            x = r.Next(gamewidth);
            y = r.Next(gameHeight);

            yvel = r.Next(2) + 5;

            radius = r.Next(10) + 5;
            brush = new SolidBrush(Color.Blue);           
        }
     
        public void Move(int gameHeight)
                     
        {             
            if (y + radius >= gameHeight)
            {
                y =  0;           
            }
            y += yvel;
        }
        public void Draw(Graphics g)
        {
            g.FillEllipse(brush, new RectangleF(x-radius,y - radius, radius * 2, radius * 2));
        }
    }

class Player
    {
       
        public float x, y, xvel;
        public Brush brush;

        public Player()
        {
       
        }

        public void DrawPlayer(Graphics g)
        {
           
            g.FillRectangle(brush, new RectangleF(x, y, 30,30));     
        }

        public void MovePlayerLeft(int gameWidth)
        {
            if (x > 0)
            {
                x -= xvel;
            }
        }
 

    }

---

Well, I don't see any collision logic at all there, but it should be as simple as checking the center of the circle + the radius in relation to the bounds of the rectangle, no? Get the circle's center point and use the distance formula to check a line from the center of teh circle to the edge against the rectangle bounds.

Quote:

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Originally Posted by BigEd781

Well, I don't see any collision logic at all there, but it should be as simple as checking the center of the circle + the radius in relation to the bounds of the rectangle, no? Get the circle's center point and use the distance formula to check a line from the center of the circle to the edge against the rectangle bounds.

---

Sorry to bother you again. How is the distance formula like? Can you please show me how the distance is calculated

1) Rectangle or Square?
2) Are all Rectangles/Squares the same size?
3) Are the circles always the same size?

Quote:

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Originally Posted by rliq

1) Rectangle or Square?
2) Are all Rectangles/Squares the same size?
3) Are the circles always the same size?

---

Hi,

Sorry for not making myself clear. Need to check the contact between the square(fixed size) and the circles(varying size) but i can make the circle fixed size if need be. I hope I'm clear. Thank you.

Collision is always a funny topic.
Usally we detect collisins by putting objects into easily comparable shapes. If it were 2 circles it would be just checking if the distance between the 2 center is lower or equal to the sum of their radius.

You can do it simple by assuming that the rectangle is a circle but that would pose problems on faces.

Or you can do it the hard way :

http://stackoverflow.com/questions/4...n-intersection