// Copyright (C) 2007 Ian Langworth
//
// MovieClip creation style described here: http://osflash.org/flashcoders/as2

class Blob extends MovieClip {

    // Needed for MovieClip to be instantiated easily
    static var symbolName = '__Packages.Blob';
    static var symbolLinked = Object.registerClass(Blob.symbolName, Blob)

    // Constants
    private static var MAX_SPEED = 20;
    private static var ACCELERATION = 2;
    private static var BOUNCE_DAMPER = .75;

    // Instance variables
    private var parent;
    private var radius;
    private var vx, vy;

    // Object constructor
    function Blob() {
        super();
    }

    // Object factory to make constructing objects easier
    static function create(parent, depth, color, x, y, radius) {
        var obj = Blob(
            parent.attachMovie(Blob.symbolName, 'Blob' + depth, depth));
        obj.init(parent, color, x, y, radius);
        return obj;
    }

    // Object initialization
    function init(parent, color, x, y, radius) {
        this.parent = parent;
        this.radius = radius;
        this.render(color, x, y, radius);
        this.vx = 0;
        this.vy = 0;
    }

    // Update a frame of the animation
    function update() {
        // Get the direction to the mouse.
        var direction = this.angleTo(this.parent._xmouse, this.parent._ymouse);

        // Calculate the distance in horizontal and vertical movement, then add
        // those to the existing velocity. Don't let the velocity exceed
        // MAX_SPEED.
        this.vx = Math.min(MAX_SPEED, this.vx + Math.cos(direction) * ACCELERATION);
        this.vy = Math.min(MAX_SPEED, this.vy + Math.sin(direction) * ACCELERATION);

        // If any blobs go off the stage, make them bounce back, but only after
        // losing a little momentum.
        if (this._x - this.radius < 0)
            this.vx = Math.abs(this.vx) * BOUNCE_DAMPER;
        if (this._y - this.radius < 0)
            this.vy = Math.abs(this.vy) * BOUNCE_DAMPER;
        if (this._x + this.radius > Stage.width)
            this.vx = -Math.abs(this.vx) * BOUNCE_DAMPER;
        if (this._y + this.radius > Stage.height)
            this.vy = -Math.abs(this.vy) * BOUNCE_DAMPER;

        // Update the position of the blob.
        this._x += this.vx;
        this._y += this.vy;
    }

    // Draw the blob as a vector (a naive way to draw a circle)
    function render(color, x, y, radius) {
        this.lineStyle(3, color);
        this.beginFill(color, 50);
        this.moveTo(0, -radius);
        this.curveTo(radius, -radius, radius, 0);
        this.curveTo(radius, radius, 0, radius);
        this.curveTo(-radius, radius, -radius, 0);
        this.curveTo(-radius, -radius, 0, -radius);
        this.endFill();
        this._x = x;
        this._y = y;
    }

    // Return the angle from the center of our blob to the given point in radians
    function angleTo(x, y) {
        return Math.atan2((y - this._y), (x - this._x));
    }

}