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.

materials在unity中是值拷贝，要新建一个数组进行赋值

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;