*

Unity/Assets/Scripts/Car/Brake.cs

@@ -0,0 +1,44 @@
+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;
+    }
+}