globalToLocal() in 3D

[SWF(frameRate=60, backgroundColor=0x000000, width=500, height=500)]
stage.quality = "medium";
var frame:Sprite = Sprite(addChild(new Sprite()));
with (frame.graphics) beginFill(0xCCCCCC), drawRect(-200, -200, 400, 400), endFill();
frame.x = stage.stageWidth / 2;
frame.y = stage.stageHeight / 2;
frame.z = 100;

var canvas:Shape = Shape(frame.addChild(new Shape()));
var msk:Shape = Shape(frame.addChild(new Shape()));
with (msk.graphics) beginFill(0x00FF00), drawRect(-200, -200, 400, 400), endFill();
canvas.mask = msk

var txt:TextField = TextField(addChild(new TextField()));
txt.defaultTextFormat = new TextFormat("_sans", 12);
txt.x = txt.y = 10;
txt.textColor = 0xFFFFFF, txt.autoSize="left", txt.text = "Draw on the 3D plane...";

stage.addEventListener(MouseEvent.MOUSE_DOWN, onDown);
stage.addEventListener(MouseEvent.MOUSE_UP, onUp);
function onDown(evt:MouseEvent):void{
	canvas.graphics.lineStyle(4, 0x000000);
	var pnt:Point = frame.globalToLocal(new Point(mouseX, mouseY));
	canvas.graphics.moveTo(pnt.x, pnt.y);
	addEventListener(Event.ENTER_FRAME, onDraw);
}
function onUp(evt:MouseEvent):void{
	removeEventListener(Event.ENTER_FRAME, onDraw);
}

var t:Number = 0;
addEventListener(Event.ENTER_FRAME, onLoop);
function onLoop(evt:Event):void {
    frame.rotationY = 35 * Math.sin(t);
	frame.rotationX = 35 * Math.cos(t);
	t+=0.02;
}

function onDraw(evt:Event):void {
        var pnt:Point = frame.globalToLocal(new Point(mouseX, mouseY));
	canvas.graphics.lineTo(pnt.x, pnt.y);
}

This demo shows that globalToLocal() works with 3D – saving us the trouble of doing some extra math if we want to draw on 3D display objects…

Have a look at the swf….

Was made aware of this trick by watching a video that kevinSuttle sent me via twitter. The video is an interview with Chris Nuuja (one of the flash player engineers).