ActionScript for Flash MX: The Definitive Guide, Second Edition

Math.ceil() Method

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

604

|

ActionScript Language Reference

rotateTowardsMouse( ), to all movie clips. It then assigns rotateTowardsMouse( ) to the

onEnterFrame( ) handler of the clip

triangle_mc, so that with every passing frame, the clip

rotates towards the mouse pointer. The same technique could be used to orient an enemy

spaceship toward a player’s spaceship.

// Convert radians to degrees. There are 2*pi radians per 360 degrees.

_global.radiansToDegrees = function (radians) {

return (radians/Math.PI) * 180;

}

// Method: MovieClip.rotateTowardsMouse()

// Desc: Rotates a clip's positive x-axis towards the mouse pointer.

MovieClip.prototype.rotateTowardsMouse = function () {

// Create a point object that stores the x- and y-coordinates of

// this clip relative to its parent's registration point.

var point = {x:this._x, y:this._y};

// Convert the clip's parent's local coordinates to global (Stage) coordinates.

this._parent.localToGlobal(point);

// Measure the distance between the registration

// point of this clip and the mouse.

var deltaX = _root._xmouse - point.x;

var deltaY = _root._ymouse - point.y;

// Calculate the angle of the line from the registration point

// of this clip to the mouse. Note that the y-coordinate is passed first.

var rotationRadian = Math.atan2(deltaY, deltaX); ...