IEnumerator Capture()
{
        yield return new WaitForEndOfFrame();
        int width = Screen.width;
        int height = Screen.height;
        Texture2D texture = new Texture2D(width,height,TextureFormat.RGB24,false);
        Rect rect = new Rect(0, 0, width, height);
        tex.ReadPixels(rect, 0, 0);
        #if UNITY_ANDROID
        texture.Apply();//不压缩
        #elif UNITY_IPHONE
        TextureScalePoint.ScalePoint (texture, width * 0.5, height * 0.5); //压缩
        #endif
        byte[] image = texture.EncodeToPNG();
        File.WriteAllBytes(Application.persistentDataPath + "/" + "capture.png",image);//存储png图
}