Collision Class

package
{
    import flash.display.MovieClip;

    public class Collision
    {
        static public var collisionSide:String = "";

        public function Collision()
        {
        }
        static public function block(character:MovieClip, wall:MovieClip):void
        {
            //Calculate the distance vector
            var vx:Number
                = (character.x + (character.width / 2))
                - (wall.x + (wall.width / 2));

            var vy:Number
                = (character.y + (character.height / 2))
                - (wall.y + (wall.height / 2));

            //Check whether vx
            //is less than the combined half widths
            if(Math.abs(vx) < character.width / 2 + wall.width / 2)
            {
                //A collision might be occurring! Check
                //whether vy is less than the combined half heights
                if(Math.abs(vy) < character.height / 2 + wall.height / 2)
                {
                    //A collision has ocurred! This is good!

                    //Find out the size of the overlap on both the X and Y axes
                    var overlap_X:Number
                    = character.width / 2
                        + wall.width / 2
                        - Math.abs(vx);

                    var overlap_Y:Number
                    = character.height / 2
                        + wall.height / 2
                        - Math.abs(vy);

                    //The collision has occurred on the axis with the
                    //*smallest* amount of overlap. Let's figure out which
                    //axis that is

                    if(overlap_X >=  overlap_Y)
                    {
                        //The collision is happening on the X axis
                        //But on which side? _v0's vy can tell us
                        if(vy > 0)
                        {
                            collisionSide = "Top";

                            //Move the rectangle out of the collision
                            character.y = character.y + overlap_Y;
                        }
                        else
                        {
                            collisionSide = "Bottom";

                            //Move the rectangle out of the collision
                            character.y = character.y - overlap_Y;
                        }
                    }
                    else
                    {
                        //The collision is happening on the Y axis
                        //But on which side? _v0's vx can tell us
                        if(vx > 0)
                        {
                            collisionSide = "Left";

                            //Move the rectangle out of the collision
                            character.x = character.x + overlap_X;
                        }
                        else
                        {
                            collisionSide = "Right";

                            //Move the rectangle out of the collision
                            character.x = character.x - overlap_X;
                        }
                    }
                }
                else
                {
                    //No collision
                    collisionSide = "No collision";
                }
            }
            else
            {
                //No collision
                collisionSide = "No collision";
            }
        }
    }
}