unity3D 用RenderTexture截图

private void MakeCameraImg(Camera mCam, int width, int height)
    {
        //Image mImage;
        RenderTexture rt = new RenderTexture(width, height, 0);
        mCam.pixelRect = new Rect(0, 0, Screen.width, Screen.height);
        mCam.targetTexture = rt;
        Texture2D screenShot = new Texture2D(width, height,TextureFormat.RGB24, false);
        mCam.Render();
        RenderTexture.active = rt;
        screenShot.ReadPixels(new Rect(0, 0, width, height ), 0, 0);
        mCam.targetTexture = null;
        RenderTexture.active = null;
        UnityEngine.Object.Destroy(rt);
        byte[] bytes = screenShot.EncodeToPNG();
        string filename = Application.dataPath + System.DateTime.Now.ToString("yyyy-MM-dd_HH-mm-ss") + ".png";
        System.IO.File.WriteAllBytes(filename, bytes);
    }