Unity调用外部摄像头，全屏显示摄像头画面

public class CameraTest : MonoBehaviour {

WebCamTexture camTexture;

void Start () {
StartCoroutine(CallCamera());
}

IEnumerator CallCamera()
{
yield return Application.RequestUserAuthorization(UserAuthorization.WebCam);
if (Application.HasUserAuthorization(UserAuthorization.WebCam))
{
if (camTexture != null)
camTexture.Stop();

WebCamDevice[] cameraDevices = WebCamTexture.devices;

string deviceName = cameraDevices[0].name;
Debug.Log(deviceName);

camTexture = new WebCamTexture(deviceName);
camTexture.Play();
}
}

void OnGUI()
{
if(camTexture!=null)
{
GUI.DrawTexture(new Rect(0, 0, Screen.width, Screen.height), camTexture, ScaleMode.StretchToFill);
}
}
}

public class CameraTest : MonoBehaviour {

WebCamTexture camTexture;

Image img;

public GameObject quad;

void Start () {
img = GetComponentInChildren<Image>();
StartCoroutine(CallCamera());
}

IEnumerator CallCamera()
{
yield return Application.RequestUserAuthorization(UserAuthorization.WebCam);
if (Application.HasUserAuthorization(UserAuthorization.WebCam))
{
if (camTexture != null)
camTexture.Stop();

WebCamDevice[] cameraDevices = WebCamTexture.devices;

string deviceName = cameraDevices[0].name;
Debug.Log(deviceName);

camTexture = new WebCamTexture(deviceName);
img.canvasRenderer.SetTexture(camTexture); //注意改行代码
camTexture.Play();
}
}

}