How to make my flying object amplitude up and down on the current y position?

Questions & Answers
1

I want to create 2d flying object that can waving up and down and move forward. I had put my object with position.y = 7 on the scene, but when i start the game, the object will BLINK to position.y = 0 and start amplitude up and down. Can anyone help me to fix this code so my object will start amplitude by its current y position? Below is the codes i put to my object:

using UnityEngine;
using System.Collections;

public class BirdMovement : MonoBehaviour {

	public float horizontalSpeed;
	public float verticalSpeed;
	public float amplitude;
	private Vector3 tempPosition;

	// Use this for initialization
	void Start () {
		tempPosition = transform.position;
	}
	
	// Update is called once per frames
	void Update () {
		tempPosition.x += horizontalSpeed;
		tempPosition.y = Mathf.Sin (Time.realtimeSinceStartup * verticalSpeed) * amplitude;
		transform.position = tempPosition;
	}
}
2

@nopwen
The sin calculated in the update method gives u zero in the beginning probably. Remember sin lies between 1 & -1. In your case probably 7 & -7. So it blinks to a y of zero then goes to 7 then 0 then -7 etc. Try making your angle 90° initially.

Hope this helps.