using UnityEngine;
using System.Collections;

public class CameraShake : MonoBehaviour {

	//shake part
	public const float BaseAmplitude = 0.2f;

	public float amplitude = 0;

	private float shakeStartTime;
	private float shakeDirection;

	private SkyBackground skyBg;

	public float offsetX = 0;
	public float offsetZ = 0;

	public void Start()
	{
		shakeStartTime = GameTime.time;
		shakeDirection = Random.Range(0f, 1f)*2*Mathf.PI;
		skyBg = GameObject.FindObjectOfType<SkyBackground>();
	}
	
	void FixedUpdate()
	{
		if(amplitude > 0.001f)
		{
			float dis = amplitude*Mathf.Sin((GameTime.time-shakeStartTime)*50);
			amplitude *= 0.95f;
			
			offsetX = dis*Mathf.Cos(shakeDirection);
			offsetZ = dis*Mathf.Sin(shakeDirection);

			if(skyBg != null)
			{
				skyBg.Update();
			}
		}
		else
		{
			offsetX = 0;
			offsetZ = 0;
			this.enabled = false;
		}
	}
}