Car tutorial crashed Unity

Unity Engine
1

Hello All,

Playing with the car tutorial
and got an error on the advance physics lessons and crashed Unity.

The folowing are the error reports.

  1. “System.NullReferenceException:Object reference not set to an instance of an object PlayerCar: FixedUpdate() (at Assets[A] Car Control/5 More Physics/PlayerCar.js:37”

  2. "System.NullReferenceException
    UnityEngine.Transform:set_localRotation(Quaternion value)
    UnityEngine.Transform:set_localEulerAngles (Vector3 value)
    PlayerCar:FixedUpdate() (at Assets/[A] Car Control/5 More Physics/PlayerCar.js:37

Don’t quite understand the errors yet. Is there something wrong the scripts.

Pasting that script here

Thanks,
Ray

// These transforms need to be connected in the inspector,
// so the script can identify the wheels.
var frontLeftWheel : Transform;
var frontRightWheel : Transform;
var backLeftWheel : Transform;
var backRightWheel : Transform;

// Speed is a multiplier of how much force we add to the wheels every frame
var speed = 150;
// The maximum steering angle of the wheels
var maxSteerAngle = 30;

// This is used to track if
private var hasBackWheelContact = false;

// Tweak the center of mass.
// - Low center of mass a bit towards the front
// - model a long long and not very high car
rigidbody.centerOfMass = Vector3 (0, 0, 0);
rigidbody.inertiaTensorRotation = Quaternion.identity;
rigidbody.inertiaTensor = Vector3 (1, 1, 2) * rigidbody.mass;

function FixedUpdate () {
var motorForce = speed * Input.GetAxis (“Vertical”);

// Do the wheels touch the ground?
// Apply force along the z axis of the object
if (hasBackWheelContact) {
rigidbody.AddRelativeForce (0, 0, motorForce);
}

// The horizontal is in the range [-1 … 1]
// The maximum steer
var rotation = Input.GetAxis (“Horizontal”) * maxSteerAngle;

// Set the rotation around the y-axis of both wheels
frontLeftWheel.localEulerAngles = Vector3 (0, rotation, 0);
frontRightWheel.localEulerAngles = Vector3 (0, rotation, 0);

// This tracks if the back wheels are grounded.
// Every frame we reset the variable,
// OnCollisionStay will then enable the variable if the wheel is grounded.
hasBackWheelContact = false;
}

// This is called every frame if the car collides with something.
// This is used to calculate if the wheels touch the ground.
function OnCollisionStay (collision : Collision)
{
for (var p : ContactPoint in collision.contacts)
{
// Enable hasBackWheelContact if we are touching the ground
if (p.thisCollider.transform == backLeftWheel)
hasBackWheelContact = true;
if (p.thisCollider.transform == backRightWheel)
hasBackWheelContact = true;
}
}

2

My Bad

Forgot to assign a target to transform :smile:

Ray