(function() {
    var DEFAULT_VERTICAL_SPEED = 0.0;
    var DEFAULT_HORIZONTAL_SPEED = -0.5;
    var UPDATE_INTERVAL = 20;

    this.t = 0;
    var self = this;
    this.preload = function(entityID) {
        self.intervalID = Script.setInterval(function() {
            var verticalSpeed = DEFAULT_VERTICAL_SPEED;
            var horizontalSpeed = DEFAULT_HORIZONTAL_SPEED;
            var userData = JSON.parse(Entities.getEntityProperties(entityID, ["userData"]).userData);
            if (userData !== undefined) {
                if (userData.horizontalScrollSpeed !== undefined) {
                    horizontalSpeed = userData.horizontalScrollSpeed;
                }
                if (userData.verticalScrollSpeed !== undefined) {
                    verticalSpeed = userData.verticalScrollSpeed;
                }
            }
            Entities.editEntity(entityID, { materialMappingPos: { x: horizontalSpeed * self.t, y: verticalSpeed * self.t }});
            self.t = self.t + UPDATE_INTERVAL / 1000;
        }, UPDATE_INTERVAL);
    };
    this.unload = function() {
        Script.clearInterval(self.intervalID);
    }
});