Box2D.Dynamics.Contacts.Contact.Update C# (CSharp) Method

        public void Update(IContactListener listener)
        {
            oldManifold.Set(Manifold);

            // Re-enable this contact.
            Flags |= ContactFlags.Enabled;

            bool touching;
            bool wasTouching = (Flags & ContactFlags.Touching) == ContactFlags.Touching;

            bool sensorA = FixtureA.Sensor;
            bool sensorB = FixtureB.Sensor;
            bool sensor = sensorA || sensorB;

            Body bodyA = FixtureA.Body;
            Body bodyB = FixtureB.Body;
            Transform xfA = bodyA.GetTransform();
            Transform xfB = bodyB.GetTransform();
            // log.debug("TransformA: "+xfA);
            // log.debug("TransformB: "+xfB);

            if (sensor)
            {
                Shape shapeA = FixtureA.Shape;
                Shape shapeB = FixtureB.Shape;
                touching = Pool.GetCollision().TestOverlap(shapeA, ChildIndexA, shapeB, ChildIndexB, xfA, xfB);

                // Sensors don't generate manifolds.
                Manifold.PointCount = 0;
            }
            else
            {
                Evaluate(Manifold, xfA, xfB);
                touching = Manifold.PointCount > 0;

                // Match old contact ids to new contact ids and copy the
                // stored impulses to warm start the solver.
                for (int i = 0; i < Manifold.PointCount; ++i)
                {
                    ManifoldPoint mp2 = Manifold.Points[i];
                    mp2.NormalImpulse = 0.0f;
                    mp2.TangentImpulse = 0.0f;
                    ContactID id2 = mp2.Id;

                    for (int j = 0; j < oldManifold.PointCount; ++j)
                    {
                        ManifoldPoint mp1 = oldManifold.Points[j];

                        if (mp1.Id.IsEqual(id2))
                        {
                            mp2.NormalImpulse = mp1.NormalImpulse;
                            mp2.TangentImpulse = mp1.TangentImpulse;
                            break;
                        }
                    }
                }

                if (touching != wasTouching)
                {
                    bodyA.Awake = true;
                    bodyB.Awake = true;
                }
            }

            if (touching)
            {
                Flags |= ContactFlags.Touching;
            }
            else
            {
                Flags &= ~ContactFlags.Touching;
            }

            if (listener == null)
            {
                return;
            }

            if (!wasTouching && touching)
            {
                listener.BeginContact(this);
            }

            if (wasTouching && !touching)
            {
                listener.EndContact(this);
            }

            if (!sensor && touching)
            {
                listener.PreSolve(this, oldManifold);
            }
        }