Not sure if this is a bug or just my misunderstanding. I am trying to make a mesh  parent of another mesh without changing the transforms (position, rotation and scaling) of the  child mesh in the world frame of reference Similar to this discussion Keep child's world position when parenting As shown in the above discussion I use the following kind of function to do this function makeParent(child, parent) { var invParentMatrix = Matrix.Invert(parent.getWorldMatrix());