Alpha tween for 2D toolkit sprites. Inherits NGUI's UITweener.

tk2dTweenAlpha

// Alpha tween for 2D toolkit sprites. Uses same method signatures as NGUI's
// TweenAlpha.

using UnityEngine;
using System.Collections;

[RequireComponent (typeof(tk2dBaseSprite))]
public class tk2dTweenAlpha : UITweener
{
  public float from = 0f;
	public float to = 1f;
	
	tk2dBaseSprite _sprite;
	tk2dBaseSprite Sprite
	{
		get
		{
			if (_sprite == null)
			{
				_sprite = GetComponent<tk2dBaseSprite>();
			}
			
			return _sprite;
		}
	}
	
	float alpha
	{
		get { return Sprite.color.a; }
		set { Sprite.color = new Color(Sprite.color.r, Sprite.color.g, Sprite.color.b, value); }
	}
		
	protected override void OnUpdate(float factor, bool isFinished)
	{
		alpha = Mathf.Lerp(from, to, factor);
	}
	
	public static tk2dTweenAlpha Begin (GameObject go, float duration, float alpha)
	{
		tk2dTweenAlpha comp = UITweener.Begin<tk2dTweenAlpha>(go, duration);
		comp.from = comp.alpha;
		comp.to = alpha;
		return comp;
	}
}