Trouble with local3DToGlobal()

[robertnyc]

I've been having some trouble understanding displayObject.local3DToGlobal() --

I want to determine the global (stage) x/y coordinates of a display object that's existing in Flash 3D space -- i.e. has a Z. I thought what I'd do is this (in pseudocode):


class myDisplayObject {

v3:Vector3D = new Vector3D(this.x, this.y, this.z);
pt:Point = this.local3DToGlobal(v3);
}

but apparently what I need to do is


class myDisplayObject {

v3:Vector3D = new Vector3D(this.x, this.y, this.z);
pt:Point = parent.local3DToGlobal(v3);
}

That is, the local3DToGlobal call must be called by the parent of the object. Is this true? Why? What am I not grokking here? If I do it from the object itself, it gives me wrong coordinates...


and this is also true if I do it outside a class structure as in


v3 = new Vector3D(myDisplayObject.x,myDisplayObject.y,myDis playObject.z);
pt = myDisplayObject.local3DToGlobal(v3);

as opposed to


v3 = new Vector3D(myDisplayObject.x,myDisplayObject.y,myDis playObject.z);
pt = this.local3DToGlobal(v3;)

Thanks for any info -- I can't find this documented anywhere in the Adobe docs/examples…