   get:function(mesh){
                    if (!mesh.__billdboardScale) {
                        mesh.__billdboardScale = new Hilo3d.Vector3(1, 1, 1);
                    }
                    return mesh.worldMatrix.getScaling(mesh.__billdboardScale).elements;
                }
            },
        },
        attributes:{
            a_position: 'POSITION',
            a_texcoord0:'TEXCOORD_0'
        },
        fs:`
            precision HILO_MAX_FRAGMENT_PRECISION float;
            varying vec2 v_tex