unity 给materials赋值

for (int i = 0; i < trans.transform.GetComponent<Renderer>().materials.Length; i++)
        {
            trans.transform.GetComponent<Renderer>().materials[i] = PenMgr.mInstance.m_alphaMat;
        }
 

这样是赋值不了的 
因为

Note that like all arrays returned by Unity, this returns a copy of materials array. If you want to change some materials in it, get the value, change an entry and set materials back.

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故应改成

 Material[] newBufMat = new Material[trans.transform.GetComponent<Renderer>().materials.Length];
            for (int i = 0; i < trans.transform.GetComponent<Renderer>().materials.Length; i++)
            {
                newBufMat[i] = PenMgr.mInstance.m_alphaMat;
            }

            trans.transform.GetComponent<Renderer>().materials = newBufMat;