using UnityEngine;
using System.Collections;

public class Brake : MonoBehaviour {
    public float _friction = 100;
    public float _radius = 0.2f;
    public float _area = 0.2f;
    public float _max_pressure = 10;
    public float _bias = 1;
    private float _threshold = 4.0e-4f;
    private bool _is_locked;

    public Brake() {

    }

    public Brake (float sliding, float radius, float area, float max_pressure, float bias) {
        _friction = sliding;
        _radius = radius;
        _area = area;
        _max_pressure = max_pressure * bias;
        _bias = bias;
    }

    public float GetTorque(float factor, float rotational_speed) {
        // `factor' is the fraction of maximum pressure applied. 
        float pressure = factor * _bias * _max_pressure;
        float normal = pressure * _area;
        float torque = _friction * normal * _radius;
        float velocity = _radius * rotational_speed;
        if(velocity < 0.0f)
            torque *= -1;

        // See if the brake is locked.
        if(Mathf.Abs(velocity) < (_threshold * normal)) {
            _is_locked = true;
            torque = 0.0f;
        } else {
            _is_locked = false;
        }

        return torque;
    }
}