Question by ucefemad · Jul 11, 2017 at 10:03 PM · 2d unity 2d cars wheels motor

How to access two WheelJoint2D from C#?

 public WheelJoint2D FW;
 public WheelJoint2D BW;
 JointMotor2D frontMotor;
 JointMotor2D backMotor;
 
     public float acc = 100.0f;
 
 
     // Use this for initialization
     void Start () {
       
     }
     
     // Update is called once per frame
     void Update () {
 
         if (Input.GetAxis("Vertical") > 0)
         {
             frontMotor.motorSpeed = acc * -1;
             frontMotor.maxMotorTorque = 10000;
             FW.motor = frontMotor;
             FW.useMotor = true;
 
             backMotor.motorSpeed = acc * -1;
             backMotor.maxMotorTorque = 10000;
             BW.motor = backMotor;
             BW.useMotor = true;
         }
 
         if (Input.GetAxis("Vertical") < 0)
         {
             frontMotor.motorSpeed = acc;
             frontMotor.maxMotorTorque = 10000;
             FW.motor = frontMotor;
             FW.useMotor = true;
 
             backMotor.motorSpeed = acc;
             backMotor.maxMotorTorque = 10000;
             BW.motor = backMotor;
             BW.useMotor = true;
         }
     }

I have a car body connected to two wheelJoint2D, When I Try to rotate the wheels, this code only rotates the front, it seems like it accesses only the front wheel, it doesn't see the back wheel? What am I doing wrong? Also, why can't the car be just front or rear wheel drive only? I doesn't move unless both wheel spin together at the same speed.

Add comment · Show 8

Cynikal ♦ · Jul 11, 2017 at 11:36 PM 0

Are you throwing any errors at all? Have you tried attaching a breakpoint to the back$$anonymous$$otor section to see if it's getting triggered? (it should be). Do you maybe have a script on the front wheels that applys a rotation animation, but not on the back?

Also, what do you mean by why can't the cars be just front or rear wheel drive? They can be. It's your game. Code it the way you want to.

ucefemad Cynikal ♦ · Jul 12, 2017 at 08:17 AM 0

No, it doesn't give me any error, in the WheelJoint2D properties, it shows that the first WheelJoint2D only is used, whatever it is for the front or back wheel, it's just the first WheelJoint2D, and it gives it the speed properly and everything works fine for the first wheelJoint2D, but the second WheelJoint2D isn't working at all, it's like the code can't modify any of its attributes.

So just to make sure I'm on the right path, I have the car body which is a rigidbody2d, with a polygon collider, and two WheelJoint2D, one for the front wheel, and one for the back wheel, and i attached the script to the car body. What could possibly be wrong?

Cornelis-de-Jager · Jul 12, 2017 at 01:33 AM 0

make Sure you didn't attach the Front WheelJoint2D to both the front and back

ucefemad Cornelis-de-Jager · Jul 12, 2017 at 07:19 AM 0

I'm sorry, I'm not sure what you mean, the car body has two WheelJoint2D, one for the front and one for the back, the WheelJoint2D are attached to the car body not each other.

EllisonLee · Jul 12, 2017 at 09:50 AM 0

Can you give a screenshot about the inspector of the wheel? I create a test scene just as you said and It works well. $$anonymous$$ore information will be helpful for finding the reason.

ucefemad EllisonLee · Jul 12, 2017 at 02:23 PM 0

That's the inspector

alt text