public void place2d( Transform transform, float ratio )
{
transform.position = point( ratio );
ratio += 0.001f;
if(ratio<=1.0f){
Vector3 v3Dir = point( ratio ) - transform.position;
float angle = Mathf.Atan2(v3Dir.y, v3Dir.x) * Mathf.Rad2Deg;
transform.eulerAngles = new Vector3(0, 0, angle);
}
}