HingeJoint2D and WheelJoint2D in the same List<Joint2D>

Unity Engine
1

Hello,

I have this code that loads all joints that represent wheels and spins their motors to make the “vehicle” moving.

List<Joint2D> wheelsJoints = new List<Joint2D>();
wheelsJoints.AddRange(gameObject.GetComponents<HingeJoint2D>());   wheelsJoints.AddRange(gameObject.GetComponents<WheelJoint2D>());

void DriveVehicleHandler (float speed)
{
    foreach (Joint2D joint in wheelsJoints)
    {
        JointMotor2D motor = new JointMotor2D();
        motor.motorSpeed = (vehicle.Heading == VehicleHeading.left) ? speed: -speed;
        motor.maxMotorTorque = joint.motor.maxMotorTorque;
        joint.motor = motor;
    }
}

It obviously doesnt work as Joint2D has no “motor” property.

What is a nice way to make this code work? Is there a nice clean solution? (Other than using only one type of 2D joint)? Im quite new to OOP and polymorphism.

Thank you!

2

If you know the exact joint it is you could cast it like so:

var hinge = (HingeJoint2D) joint;
3

Thank you for suggestion. I know about casting. Problem is that there are both HingeJoint2D and WheelJoint2D in the list of Joint2D thanks to polymorphism so casting fails in some cases.

I can always make two separate lists, one for HingeJoints2D and one for WheelJoints2D but I hoped that there was a better solution.

As I understand it, if both HingeJoint2D and WheelJoint2D inherited from same class that has motor property, my code would work. I hoped that someone could explain a little bit better if there is something I can do.