Getting NullReferenceException when Spawning via GameManager

Hello,
I do have the UnityStandardAssets Car and want to spawn this via a GameManager.
When I spawn the car before the game start manually I have no problem at all.

When I spawn it via the game Manager I get the Error:

Code (CSharp):

1. NullReferenceException: Object reference not set to an instance of an object.
2. UnityStandardAssets.Vehicles.Car.CarController.get_CurrentSpeed() (at Assets/Car/Scripts/CarController.cs:54)

The CarController.cs is the standard CarController from Unity:

Code (CSharp):

1. using System;
2. using UnityEngine;
3.  
4. namespace UnityStandardAssets.Vehicles.Car
5. {
6.     internal enum CarDriveType
7.     {
8.         FrontWheelDrive,
9.         RearWheelDrive,
10.         FourWheelDrive
11.     }
12.  
13.     internal enum SpeedType
14.     {
15.         MPH,
16.         KPH
17.     }
18.  
19.     public class CarController : MonoBehaviour
20.     {
21.         [SerializeField] private CarDriveType m_CarDriveType = CarDriveType.FourWheelDrive;
22.         [SerializeField] private WheelCollider[] m_WheelColliders = new WheelCollider[4];
23.         [SerializeField] private GameObject[] m_WheelMeshes = new GameObject[4];
24.         [SerializeField] private WheelEffects[] m_WheelEffects = new WheelEffects[4];
25.         [SerializeField] private Vector3 m_CentreOfMassOffset;
26.         [SerializeField] private float m_MaximumSteerAngle;
27.         [Range(0, 1)] [SerializeField] private float m_SteerHelper; // 0 is raw physics , 1 the car will grip in the direction it is facing
28.         [Range(0, 1)] [SerializeField] private float m_TractionControl; // 0 is no traction control, 1 is full interference
29.         [SerializeField] private float m_FullTorqueOverAllWheels;
30.         [SerializeField] private float m_ReverseTorque;
31.         [SerializeField] private float m_MaxHandbrakeTorque;
32.         [SerializeField] private float m_Downforce = 400f;
33.         [SerializeField] private SpeedType m_SpeedType;
34.         [SerializeField] private float m_Topspeed = 200;
35.         [SerializeField] private static int NoOfGears = 5;
36.         [SerializeField] private float m_RevRangeBoundary = 1f;
37.         [SerializeField] private float m_SlipLimit;
38.         [SerializeField] private float m_BrakeTorque;
39.  
40.         private Quaternion[] m_WheelMeshLocalRotations;
41.         private Vector3 m_Prevpos, m_Pos;
42.         private float m_SteerAngle;
43.         private int m_GearNum;
44.         private float m_GearFactor;
45.         private float m_OldRotation;
46.         private float m_CurrentTorque;
47.         private Rigidbody m_Rigidbody;
48.         private const float k_ReversingThreshold = 0.01f;
49.         private float m_Orientation;
50.  
51.         public bool Skidding { get; private set; }
52.         public float BrakeInput { get; private set; }
53.         public float CurrentSteerAngle { get { return m_SteerAngle; } }
54.         public float CurrentSpeed { get { return m_Rigidbody.velocity.magnitude * 2.23693629f; } }
55.         public float MaxSpeed { get { return m_Topspeed; } }
56.         public float Revs { get; private set; }
57.         public float AccelInput { get; private set; }
58.         // Use this for initialization
59.         private void Start()
60.         {
61.             m_WheelMeshLocalRotations = new Quaternion[4];
62.             for (int i = 0; i < 4; i++)
63.             {
64.                 m_WheelMeshLocalRotations[i] = m_WheelMeshes[i].transform.localRotation;
65.             }
66.             m_WheelColliders[0].attachedRigidbody.centerOfMass = m_CentreOfMassOffset;
67.  
68.             m_MaxHandbrakeTorque = float.MaxValue;
69.  
70.             m_Rigidbody = GetComponent<Rigidbody>();
71.             m_CurrentTorque = m_FullTorqueOverAllWheels - (m_TractionControl * m_FullTorqueOverAllWheels);
72.         }
73.  
74.         private void GearChanging()
75.         {
76.             float f = Mathf.Abs(CurrentSpeed / MaxSpeed);
77.             float upgearlimit = (1 / (float)NoOfGears) * (m_GearNum + 1);
78.             float downgearlimit = (1 / (float)NoOfGears) * m_GearNum;
79.  
80.             if (m_GearNum > 0 && f < downgearlimit)
81.             {
82.                 m_GearNum--;
83.             }
84.  
85.             if (f > upgearlimit && (m_GearNum < (NoOfGears - 1)))
86.             {
87.                 m_GearNum++;
88.             }
89.         }
90.  
91.  
92.         // simple function to add a curved bias towards 1 for a value in the 0-1 range
93.         private static float CurveFactor(float factor)
94.         {
95.             return 1 - (1 - factor) * (1 - factor);
96.         }
97.  
98.  
99.         // unclamped version of Lerp, to allow value to exceed the from-to range
100.         private static float ULerp(float from, float to, float value)
101.         {
102.             return (1.0f - value) * from + value * to;
103.         }
104.  
105.  
106.         private void CalculateGearFactor()
107.         {
108.             float f = (1 / (float)NoOfGears);
109.             // gear factor is a normalised representation of the current speed within the current gear's range of speeds.
110.             // We smooth towards the 'target' gear factor, so that revs don't instantly snap up or down when changing gear.
111.             var targetGearFactor = Mathf.InverseLerp(f * m_GearNum, f * (m_GearNum + 1), Mathf.Abs(CurrentSpeed / MaxSpeed));
112.             m_GearFactor = Mathf.Lerp(m_GearFactor, targetGearFactor, Time.deltaTime * 5f);
113.         }
114.  
115.  
116.         private void CalculateRevs()
117.         {
118.             // calculate engine revs (for display / sound)
119.             // (this is done in retrospect - revs are not used in force/power calculations)
120.             CalculateGearFactor();
121.             var gearNumFactor = m_GearNum / (float)NoOfGears;
122.             var revsRangeMin = ULerp(0f, m_RevRangeBoundary, CurveFactor(gearNumFactor));
123.             var revsRangeMax = ULerp(m_RevRangeBoundary, 1f, gearNumFactor);
124.             Revs = ULerp(revsRangeMin, revsRangeMax, m_GearFactor);
125.         }
126.  
127.  
128.         public void Move(float steering, float accel, float footbrake, float handbrake)
129.         {
130.             for (int i = 0; i < 4; i++)
131.             {
132.                 Quaternion quat;
133.                 Vector3 position;
134.                 m_WheelColliders[i].GetWorldPose(out position, out quat);
135.                 m_WheelMeshes[i].transform.position = position;
136.                 m_WheelMeshes[i].transform.rotation = quat;
137.             }
138.  
139.             //clamp input values
140.             steering = Mathf.Clamp(steering, -1, 1);
141.             AccelInput = accel = Mathf.Clamp(accel, 0, 1);
142.             BrakeInput = footbrake = -1 * Mathf.Clamp(footbrake, -1, 0);
143.             handbrake = Mathf.Clamp(handbrake, 0, 1);
144.  
145.             //Set the steer on the front wheels.
146.             //Assuming that wheels 0 and 1 are the front wheels.
147.             m_SteerAngle = steering * m_MaximumSteerAngle;
148.             m_WheelColliders[0].steerAngle = m_SteerAngle;
149.             m_WheelColliders[1].steerAngle = m_SteerAngle;
150.  
151.             SteerHelper();
152.             ApplyDrive(accel, footbrake);
153.             CapSpeed();
154.  
155.             //Set the handbrake.
156.             //Assuming that wheels 2 and 3 are the rear wheels.
157.             if (handbrake > 0f)
158.             {
159.                 var hbTorque = handbrake * m_MaxHandbrakeTorque;
160.                 m_WheelColliders[2].brakeTorque = hbTorque;
161.                 m_WheelColliders[3].brakeTorque = hbTorque;
162.             }
163.  
164.  
165.             CalculateRevs();
166.             GearChanging();
167.  
168.             AddDownForce();
169.             CheckForWheelSpin();
170.             TractionControl();
171.         }
172.  
173.  
174.         private void CapSpeed()
175.         {
176.             float speed = m_Rigidbody.velocity.magnitude;
177.             switch (m_SpeedType)
178.             {
179.                 case SpeedType.MPH:
180.  
181.                     speed *= 2.23693629f;
182.                     if (speed > m_Topspeed)
183.                         m_Rigidbody.velocity = (m_Topspeed / 2.23693629f) * m_Rigidbody.velocity.normalized;
184.                     break;
185.  
186.                 case SpeedType.KPH:
187.                     speed *= 3.6f;
188.                     if (speed > m_Topspeed)
189.                         m_Rigidbody.velocity = (m_Topspeed / 3.6f) * m_Rigidbody.velocity.normalized;
190.                     break;
191.             }
192.         }
193.  
194.  
195.         private void ApplyDrive(float accel, float footbrake)
196.         {
197.  
198.             float thrustTorque;
199.             switch (m_CarDriveType)
200.             {
201.                 case CarDriveType.FourWheelDrive:
202.                     thrustTorque = accel * (m_CurrentTorque / 4f);
203.                     for (int i = 0; i < 4; i++)
204.                     {
205.                         m_WheelColliders[i].motorTorque = thrustTorque;
206.                     }
207.                     break;
208.  
209.                 case CarDriveType.FrontWheelDrive:
210.                     thrustTorque = accel * (m_CurrentTorque / 2f);
211.                     m_WheelColliders[0].motorTorque = m_WheelColliders[1].motorTorque = thrustTorque;
212.                     break;
213.  
214.                 case CarDriveType.RearWheelDrive:
215.                     thrustTorque = accel * (m_CurrentTorque / 2f);
216.                     m_WheelColliders[2].motorTorque = m_WheelColliders[3].motorTorque = thrustTorque;
217.                     break;
218.  
219.             }
220.  
221.             for (int i = 0; i < 4; i++)
222.             {
223.                 if (CurrentSpeed > 5 && Vector3.Angle(transform.forward, m_Rigidbody.velocity) < 50f)
224.                 {
225.                     m_WheelColliders[i].brakeTorque = m_BrakeTorque * footbrake;
226.                 }
227.                 else if (footbrake > 0)
228.                 {
229.                     m_WheelColliders[i].brakeTorque = 0f;
230.                     m_WheelColliders[i].motorTorque = -m_ReverseTorque * footbrake;
231.                 }
232.             }
233.         }
234.  
235.  
236.         private void SteerHelper()
237.         {
238.             for (int i = 0; i < 4; i++)
239.             {
240.                 WheelHit wheelhit;
241.                 m_WheelColliders[i].GetGroundHit(out wheelhit);
242.                 if (wheelhit.normal == Vector3.zero)
243.                     return; // wheels arent on the ground so dont realign the rigidbody velocity
244.             }
245.  
246.             // this if is needed to avoid gimbal lock problems that will make the car suddenly shift direction
247.             if (Mathf.Abs(m_OldRotation - transform.eulerAngles.y) < 10f)
248.             {
249.                 var turnadjust = (transform.eulerAngles.y - m_OldRotation) * m_SteerHelper;
250.                 Quaternion velRotation = Quaternion.AngleAxis(turnadjust, Vector3.up);
251.                 m_Rigidbody.velocity = velRotation * m_Rigidbody.velocity;
252.             }
253.             m_OldRotation = transform.eulerAngles.y;
254.         }
255.  
256.  
257.         // this is used to add more grip in relation to speed
258.         private void AddDownForce()
259.         {
260.             m_WheelColliders[0].attachedRigidbody.AddForce(-transform.up * m_Downforce *
261.                                                          m_WheelColliders[0].attachedRigidbody.velocity.magnitude);
262.         }
263.  
264.  
265.         // checks if the wheels are spinning and is so does three things
266.         // 1) emits particles
267.         // 2) plays tiure skidding sounds
268.         // 3) leaves skidmarks on the ground
269.         // these effects are controlled through the WheelEffects class
270.         private void CheckForWheelSpin()
271.         {
272.             // loop through all wheels
273.             for (int i = 0; i < 4; i++)
274.             {
275.                 WheelHit wheelHit;
276.                 m_WheelColliders[i].GetGroundHit(out wheelHit);
277.  
278.                 // is the tire slipping above the given threshhold
279.                 if (Mathf.Abs(wheelHit.forwardSlip) >= m_SlipLimit || Mathf.Abs(wheelHit.sidewaysSlip) >= m_SlipLimit)
280.                 {
281.                     m_WheelEffects[i].EmitTyreSmoke();
282.  
283.                     // avoiding all four tires screeching at the same time
284.                     // if they do it can lead to some strange audio artefacts
285.                     if (!AnySkidSoundPlaying())
286.                     {
287.                         m_WheelEffects[i].PlayAudio();
288.                     }
289.                     continue;
290.                 }
291.  
292.                 // if it wasnt slipping stop all the audio
293.                 if (m_WheelEffects[i].PlayingAudio)
294.                 {
295.                     m_WheelEffects[i].StopAudio();
296.                 }
297.                 // end the trail generation
298.                 m_WheelEffects[i].EndSkidTrail();
299.             }
300.         }
301.  
302.         // crude traction control that reduces the power to wheel if the car is wheel spinning too much
303.         private void TractionControl()
304.         {
305.             WheelHit wheelHit;
306.             switch (m_CarDriveType)
307.             {
308.                 case CarDriveType.FourWheelDrive:
309.                     // loop through all wheels
310.                     for (int i = 0; i < 4; i++)
311.                     {
312.                         m_WheelColliders[i].GetGroundHit(out wheelHit);
313.  
314.                         AdjustTorque(wheelHit.forwardSlip);
315.                     }
316.                     break;
317.  
318.                 case CarDriveType.RearWheelDrive:
319.                     m_WheelColliders[2].GetGroundHit(out wheelHit);
320.                     AdjustTorque(wheelHit.forwardSlip);
321.  
322.                     m_WheelColliders[3].GetGroundHit(out wheelHit);
323.                     AdjustTorque(wheelHit.forwardSlip);
324.                     break;
325.  
326.                 case CarDriveType.FrontWheelDrive:
327.                     m_WheelColliders[0].GetGroundHit(out wheelHit);
328.                     AdjustTorque(wheelHit.forwardSlip);
329.  
330.                     m_WheelColliders[1].GetGroundHit(out wheelHit);
331.                     AdjustTorque(wheelHit.forwardSlip);
332.                     break;
333.             }
334.         }
335.  
336.  
337.         private void AdjustTorque(float forwardSlip)
338.         {
339.             if (forwardSlip >= m_SlipLimit && m_CurrentTorque >= 0)
340.             {
341.                 m_CurrentTorque -= 10 * m_TractionControl;
342.             }
343.             else
344.             {
345.                 m_CurrentTorque += 10 * m_TractionControl;
346.                 if (m_CurrentTorque > m_FullTorqueOverAllWheels)
347.                 {
348.                     m_CurrentTorque = m_FullTorqueOverAllWheels;
349.                 }
350.             }
351.         }
352.  
353.  
354.         private bool AnySkidSoundPlaying()
355.         {
356.             for (int i = 0; i < 4; i++)
357.             {
358.                 if (m_WheelEffects[i].PlayingAudio)
359.                 {
360.                     return true;
361.                 }
362.             }
363.             return false;
364.         }
365.     }
366. }

My GameManager calls my CarManager, which spawns my Objects.

My GameManager.cs looks like:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class GameManager : MonoBehaviour {
6.     public int m_Rounds = 100;
7.     public GameObject m_CarPrefab;
8.     public CarManager[] m_Cars;
9.     private int m_RoundNumber;
10.     // Use this for initialization
11.     void Start () {
12.         SpawnCars();
13.     }
14.  
15.     // Update is called once per frame
16.     void Update () {
17.      
18.     }
19.     private void SpawnCars()
20.     {
21.         for(int i=0;i<m_Cars.Length; i++)
22.         {
23.             m_Cars[i].m_Instance = Instantiate(m_CarPrefab, m_Cars[i].m_SpawnPoint.position, m_Cars[i].m_SpawnPoint.rotation) as GameObject;
24.             m_Cars[i].Setup();
25.         }
26.     }
27. }
28.  

and my CarManager.cs looks like:

Code (CSharp):

1. using System;
2. using UnityEngine;
3. using UnityStandardAssets.Vehicles.Car;
4.  
5. [Serializable]
6. public class CarManager {
7.     public Transform m_SpawnPoint;
8.     [HideInInspector] public GameObject m_Instance;
9.     public int initialVelocity;
10.  
11.     private CarController car_Control;
12.     // Use this for initialization
13.     public void Setup()
14.     {
15.         car_Control = m_Instance.GetComponent<CarController>();
16.         car_Control.m_Speed = initialVelocity;
17.     }
18.  
19.     // Update is called once per frame
20.     void Update () {
21.      
22.     }
23. }
24.  

Any suggestions?

-Kind regards,

 

It's probably the rigidbody that is showing null.

 

I believe you are correct, @fire7side . The Setup() is being called before the car's Start(), I think.
You could try to change your SpawnCars (or turn Start into one*, in the same script) to a Coroutine.
Spawn all of the cars, then yield a frame and do the Setup().