NGUI与特效的层级关系

通过调整特效的 render queue 来解决特效与NGUI界面之间的层级关系问题，用以下脚本解决：

using System.Collections.Generic;
using UnityEngine;

public class UIRenderQueueSorter : MonoBehaviour
{
    [SerializeField]
    UIWidget m_source;
    [SerializeField]
    int m_offset;
    [SerializeField]
    List<Renderer> m_renderers = new List<Renderer>();

    public void Initialize()
    {
        Renderer[] renders = transform.GetComponentsInChildren<Renderer>(true);
        m_renderers.AddRange(renders);
    }

    void Update()
    {
        if (m_source && m_renderers.Count > 0)
        {
            for (int i = 0; i < m_renderers.Count; i++)
            {
                Renderer r = m_renderers[i];
                if (r && r.sharedMaterial && m_source.drawCall != null)
                    r.sharedMaterial.renderQueue = m_source.drawCall.renderQueue + m_offset;
            }
        }
    }

    public void AddRenderer(Renderer r)
    {
        if (!m_renderers.Contains(r))
        {
            m_renderers.Add(r);
        }
    }

    public void ClearAllRenderers()
    {
        m_renderers.Clear();
    }

    public UIWidget Source
    {
        set { m_source = value; }
    }

    public int Offset
    {
        set { m_offset = value; }
    }
}