# Collision Helper

There are many ways we could organize the methods we saw in the previous section, but one particularly apt one is to organize them into a static helper class, much like our `Math`

and `MathHelper`

classes, i.e. `CollisionHelper`

:

```
/// <summary>
/// A class containing collision detection methods
/// </summary>
public static class CollisionHelper
{
/// <summary>
/// Detects a collision between two points
/// </summary>
/// <param name="p1">the first point</param>
/// <param name="p2">the second point</param>
/// <returns>true when colliding, false otherwise</returns>
public static bool Collides(BoundingPoint p1, BoundingPoint p2)
{
return p1.X == p2.X && p1.Y == p2.Y;
}
// ... more static collision detection methods
}
```

With such a helper in place, we could also go back and expand our structures, i.e.:

```
/// <summary>
/// A class representing a bounding point for determining collisions
/// </summary>
public struct BoundingPoint
{
public float X;
public float Y;
/// <summary>
/// Constructs a BoundingPoint with the provided coordinates
/// </summary>
/// <param name="x">The x coordinate</param>
/// <param name="y">The y coordinate</param>
public BoundingPoint(float x, float y)
{
X = x;
Y = y;
}
/// <summary>
/// Determines if this BoundingPoint collides with another BoundingPoint
/// </summary>
/// <param name="o">the other bounding point</param>
/// <returns>true on collision, false otherwise</returns>
public bool CollidesWith(BoundingPoint o)
{
return CollisionHelper.Collides(o, this);
}
/// <summary>
/// Determines if this BoundingPoint collides with a BoundingCircle
/// </summary>
/// <param name="c">the BoundingCircle</param>
/// <returns>true on collision, false otherwise</returns>
public bool CollidesWith(BoundingCircle c)
{
return CollisionHelper.Collides(c, this);
}
/// <summary>
/// Determines if this BoundingPoint collides with a BoundingCircle
/// </summary>
/// <param name="r">the BoundingRectangle</param>
/// <returns>true on collision, false otherwise</returns>
public bool CollidesWith(BoundingRectangle r)
{
return CollisionHelper.Collides(r, this);
}
}
```

We could, of course, directly implement the collision methods within the structs, but this approach avoids duplicating code. It also more closely follows the style of the XNA framework.

Warning

For your collision detection to be accurate, you must keep your bounding volumes in sync with your sprites - i.e. every time you move a sprite, you must also move its bounding volume. Alternatively, you may wish to *create* yh