キャンバスパーティクル.cs

using UnityEngine;
using UnityEngine.UI;
using System.Collections;
using DG.Tweening;

// Screen Space - Overrayで使える2Dパーティクル

[RequireComponent (typeof (CanvasGroup))]
public class CanvasParticle : MonoBehaviour {

	public int particleNum = 5;
	public GameObject prefab;

	// パーティクルサイズ
	public float minWidth = 10.0f;
	public float maxWidth = 20.0f;

	public float minRadius = 50.0f;
	public float maxRadius = 100.0f;

	public float fadeTime = 1.0f;


	void Start () {
		var rectTransform = this.GetComponent<RectTransform> ();

		for (int i = 0; i < particleNum; i++) {
			var go = Instantiate (prefab) as GameObject;
			var rect = go.GetComponent<RectTransform>();

			// 親
			rect.SetParent(this.transform);

			// 位置はこれ自身と同じ
			//rect.anchoredPosition = rectTransform.anchoredPosition;
			rect.anchoredPosition = Vector2.zero;

			// 色はランダム
			var image = go.GetComponent<Image>();
			image.color = Color.HSVToRGB (Random.value, 1.0f, 1.0f);

			// 飛ぶ方向はランダム
			var rad = Mathf.PI * 2.0f * Random.value;
			var radius = Random.Range (minRadius, maxRadius);
			Vector2 targetPosition = rect.anchoredPosition + new Vector2 (radius * Mathf.Cos (rad), radius * Mathf.Sin (rad));
			rect.DOAnchorPos (targetPosition, fadeTime).SetEase (Ease.Linear);

			// サイズ
			float size = Random.Range(minWidth, maxWidth);
			rect.sizeDelta = Vector2.one * size;
		}

		// フェードする
		this.GetComponent<CanvasGroup>().DOFade(0.0f, fadeTime);

		Destroy (this.gameObject, fadeTime + 1.0f);
	}
}