Extract derived 3D scaling from a 3D Sprite to set to a 2D billboard
- by Bill Kotsias
I am trying to get the derived position and scaling of a 3D Sprite and set them to a 2D Sprite.
I have managed to do the first part like this:
var p:Point = sprite3d.local3DToGlobal(new Vector3D(0,0,0));
billboard.x = p.x;
billboard.y = p.y;
But I can't get the scaling part correctly. I am trying this:
var mat:Matrix3D = sprite3d.transform.getRelativeMatrix3D(stage); // get derived matrix(?)
var scaleV:Vector3D = mat.decompose()[2]; // get scaling vector from derived matrix
var scale:Number = scaleV.length;
billboard.scaleX = scale;
billboard.scaleY = scale;
...but the result is apparently wrong.
PS. One might ask what I am trying to achieve. I am trying to create "billboard" 3D sprites, i.e. sprites which are affected by all 3D transformations except rotations, thus they always face the "camera".
