Im trying to use the raycast function of B2World . I need to provide a “call back function” when I use it.

```
/**
* Ray-cast the world for all fixtures in the path of the ray. Your callback
* Controls whether you get the closest point, any point, or n-points
* The ray-cast ignores shapes that contain the starting point
* @param callback A callback function which must be of signature:
* <code>function Callback(fixture:B2Fixture, // The fixture hit by the ray
* point:B2Vec2, // The point of initial intersection
* normal:B2Vec2, // The normal vector at the point of intersection
* fraction:Float // The fractional length along the ray of the intersection
* ):Float
* </code>
* Callback should return the new length of the ray as a fraction of the original length.
* By returning 0, you immediately terminate.
* By returning 1, you continue wiht the original ray.
* By returning the current fraction, you proceed to find the closest point.
* @param point1 the ray starting point
* @param point2 the ray ending point
*/
public function rayCast(callbackMethod:B2Fixture -> B2Vec2 -> B2Vec2 -> Float -> Dynamic, point1:B2Vec2, point2:B2Vec2):Void
{
var broadPhase:IBroadPhase = m_contactManager.m_broadPhase;
var output:B2RayCastOutput = new B2RayCastOutput ();
function rayCastWrapper(input:B2RayCastInput, proxy:Dynamic):Float
{
var userData:Dynamic = broadPhase.getUserData(proxy);
var fixture:B2Fixture = cast (userData, B2Fixture);
var hit:Bool = fixture.rayCast(output, input);
if (hit)
{
var fraction:Float = output.fraction;
var point:B2Vec2 = new B2Vec2(
(1.0 - fraction) * point1.x + fraction * point2.x,
(1.0 - fraction) * point1.y + fraction * point2.y);
return callbackMethod(fixture, point, output.normal, fraction);
}
return input.maxFraction;
}
var input:B2RayCastInput = new B2RayCastInput(point1, point2);
broadPhase.rayCast(rayCastWrapper, input);
}
```

So my code is:

```
m_world.rayCast(rcCallback, p1, p2);
```

and my callback function is:

```
private function rcCallback(fixture:B2Fixture, point:B2Vec2, normal:B2Vec2, fraction:Float):Float
{
if (fixture.getFilterData().groupIndex==-1)
{
return -1;
}
return fraction;
}
```

I have never really done this type of thing with callbacks before so I don’t really understand.

but the function only returns void. I’m probably doing something wrong.