Well, that was easy:
public static function
getArcballMatrix(n1:Number3D,n2:Number3D,center:Number3D=
null,oMatrix:MatrixAway3D=null):MatrixAway3D
{
if(center == null) center = new Number3D;
// var center:Number3D =
obj.scenePivotPoint//new
Number3D(0,0,0)//uiball.position//new Number3D(0,0,0);
var p1:Number3D =n1
p1.sub(p1,center);
// p1.y = -p1.y;
var p2:Number3D = new Number3D;
p2.clone(n2);
//p2.scale(p2,.1);
//p2.y = -p2.y;
p2.sub(p2,center);
//trace(nn2,cP)
// c; //0,0,0
p1.normalize();
p2.normalize()
var cross:Number3D = new Number3D;
cross.cross(p1,p2);
var pos:Array = [cross.x,cross.y,cross.z]
var len:Number = cross.modulo;
var angle:Number = Math.acos(len)
var q:Quaternion = new Quaternion;
q.axis2quaternion(pos[0],pos[1],pos[2],angle);
//q.normalize(1)
var mat:MatrixAway3D = new MatrixAway3D;
mat.quaternion2matrix(q);
if(oMatrix){
mat.multiply3x3( mat, oMatrix);
//mat.normalize(oMatrix)
}
return mat;
}
only trouble is that one axis of motion needs to be flipped...
