Unity：在 GameObject 上实例化预制件 - 错误对象为空

Question

在我的 Unity 游戏中，我有一个使用 Edy 的车辆物理资产的车辆预制件。我正在尝试根据 GameObject 的位置和旋转实例化选定的车辆预制件。

当运行我的代码在场景中生成载具时出现此错误

ArgumentException: The Object you want to instantiate is null

ArgumentException: The Object you want to instantiate is null. UnityEngine.Object.CheckNullArgument (System.Object arg, System.String message) (at C:/buildslave/unity/build/Runtime/Export/UnityEngineObject.cs:239) UnityEngine.Object.Instantiate (UnityEngine.Object original, Vector3 position, Quaternion rotation) (at C:/buildslave/unity/build/Runtime/Export/UnityEngineObject.cs:151) UnityEngine.Object.Instantiate[VehicleController] (EVP.VehicleController original, Vector3 position, Quaternion rotation) (at C:/buildslave/unity/build/Runtime/Export/UnityEngineObject.cs:206) VehicleSpawner.spawnVehiclesInFirstGarage () (at Assets/Scripts/VehicleSpawner.cs:44) HandleGarage.Start () (at Assets/Scripts/HandleGarage.cs:59)

Vehicle Prefab 为空，因为车辆将由用户在游戏中选择。（即使我 select 一个车辆预制件我仍然得到同样的错误）

我在游戏对象上实例化车辆预制件的代码

public EVP.VehicleTelemetry telemetryComponent;
public EVP.VehicleController vehiclePrefab;
public GameObject spawnObject;

public void spawnVehiclesInFirstGarage ()
{
    // Load saved JSON
    string jsonData = SecurePlayerPrefs.GetString ("vehicleNames");

    // Convert to Class
    Database loadedData = JsonUtility.FromJson<Database> (jsonData);

    // Loop through Owned Vehicles Garage
    for (int i = 0; i < loadedData.vehicleNames.Count; i++) {

        // Set up instantiate
        var vehicle = Resources.Load("Prefabs/" + (loadedData.vehicleNames [i]));
        vehiclePrefab = vehicle as EVP.VehicleController;

        // Spawn vehicle on game object
        EVP.VehicleController newVehicle = Instantiate(vehiclePrefab, spawnObject.transform.position, spawnObject.transform.rotation) as EVP.VehicleController;
        telemetryComponent.target = newVehicle;
    }
}

Answer 1

可能的解决方案

vehiclePrefab = vehicle as EVP.VehicleController; 可能会导致问题，因为记录 var vehicle = Resources.Load("Prefabs/" + (loadedData.vehicleNames [i])); 已经给出 Sport Coupe (UnityEngine.GameObject)，这是正确的类型。

而不是使用 as EVP.VehicleController，尝试：

// Set up instantiate
var vehiclePrefab = Resources.Load("Prefabs/" + (loadedData.vehicleNames [i])) as GameObject;

// Spawn vehicle on game object
GameObject newVehicle = Instantiate(vehiclePrefab, spawnObject.transform.position, spawnObject.transform.rotation);
EVP.VehicleController controller = newVehicle.GetComponent<EVP.VehicleController>();
telemetryComponent.target = newVehicle;

本文来自Unity's documentation for loading prefabs via scripting.

从错误信息来看，似乎是在void Start()中调用了spawnVehiclesInFirstGarage()。如果是这样，请尝试将其放入 void Update()，添加一个 if( prefab != null && !isInstantiated) 检查。

其他故障排除（如果解决方案不起作用）

尝试通过检查器分配预制件，看看是否遇到同样的问题。
在您现有的代码上，尝试 Debug.Log(vehiclePrefab)。

Unity：在 GameObject 上实例化预制件 - 错误对象为空

Unity: Instantiating prefab on GameObject - Error Object is null

unity3d

instantiation

gameobject

可能的解决方案

其他故障排除（如果解决方案不起作用）