php backpack

<?php>

    $BACKPACK_SMALL  = 1;
    $BACKPACK_MEDIUM = 2;
    $BACKPACK_LARGE  = 3;

    $BACKPACK_STATE_PLAYER  = 1;
    $BACKPACK_STATE_WORLD   = 2;
    $BACKBACK_STATE_VEHICLE = 3;

    class Backpack {

        public $created = true;
        public $size;
        public $model;
        public $state;

        public $object;
        public $x;
        public $y;
        public $z;

        public function createBackpack($size, $state, $id = null) {
            $this->size = $size;
            $this->state = $state;

            switch($this->size) {
                case $BACKPACK_SMALL:
                    $this->model = 0;
                    break;
                case $BACKPACK_MEDIUM:
                    $this->model = 0;
                    break;
                case $BACKPACK_LARGE:
                    $this->model = 0;
                    break;
            }

            if(this->state != BACKPACK_STATE_WORLD) {

            }


        }

        public function setPosition($x, $y, $z) {
            if(this->state == $BACKPACK_STATE_WORLD) {
                $this->x = $x;
                $this->y = $y;
                $this->z = $z;

                Object::create(this->, $x, $y, $z, $rX = 0.0, $rY = 0.0, $rZ = 0.0, $drawDistance = 0.0);
            }
        }



    }

?>