How to rotate an object without showing the underside?

Hello,

I´m rotating an object in iOS (on touch) through the following code:

function Update () {

if (Input.touchCount == 1) {
var touch : Touch = Input.GetTouch(0);

if (touch.phase == TouchPhase.Moved) {

h = horizontalSpeed * touch.deltaPosition.x;
transform.Rotate(0, -h, 0, Space.World);
v = verticalSpeed * touch.deltaPosition.y;
transform.Rotate(v, 0, 0, Space.World);
}
}
}

How do I change this so that the underside of the object is never shown?

you need to define bounds for the value

somthing like

h = horizontalSpeed * touch.deltaPosition.x;

if(h>0 && themodel.transform.eulerangels.y <90)
{
transform.Rotate(0, -h, 0, Space.World);

}

you only need to do this for the y value