duck

// extroadinarily simple car behaviour
// robotduck 2011

using UnityEngine;
using System.Collections;

public class Car : MonoBehaviour {

    public float maxSpeed = 100;
    public float enginePower = 20;
    public float minTurnForce = 0.1f;
    public float maxTurnForce = 0.6f;
    public float lateralGrip = 3;

    bool onGround;
    Vector3 oPosition;
    Quaternion oRotation;
    float h,v;

    void Start () {
        oPosition = transform.position;
        oRotation = transform.rotation;
        collider.material.dynamicFriction = 0;
        collider.material.staticFriction = 0;
        rigidbody.angularDrag = 2;
        rigidbody.drag = 0.1f;
    }


    void OnCollisionStay(Collision col)
    {
        if (Vector3.Angle(transform.up, Vector3.up) < 65)
        {
            onGround = true;
        }
    }

    void FixedUpdate()
    {
        if (onGround)
        {
            Vector3 localVelocity = transform.InverseTransformDirection(rigidbody.velocity);

            float currentSpeed = localVelocity.z;
            float inverseSpeedFactor = Mathf.InverseLerp( maxSpeed, 0, Mathf.Abs(currentSpeed) );
            float accelPower = enginePower * inverseSpeedFactor;

            Vector3 accelForce = transform.forward * accelPower * v;
            Vector3 gripForce = -transform.right * lateralGrip * localVelocity.x;
            Vector3 sumForce = accelForce + gripForce;
            Vector3 turnTorque = currentSpeed * transform.up * h * Mathf.Lerp(minTurnForce, maxTurnForce, inverseSpeedFactor);

            rigidbody.AddForce( sumForce );
            rigidbody.AddTorque( turnTorque );
        }
        onGround = false;
    }

    void Update () {
        if (Input.GetKeyDown("r")) { Reset(); }
        v = Input.GetAxis("Vertical");
        h = Input.GetAxis("Horizontal");
    }

    void Reset()
    {
        transform.position = oPosition;
        transform.rotation = oRotation;
        rigidbody.velocity = Vector3.zero;
        rigidbody.angularVelocity = Vector3.zero;
    }
}