public override void Update(GameTime gameTime)
{
float timeDelta = (float)gameTime.ElapsedGameTime.TotalSeconds;
float smoothRate;
steeringBehaviours.timeDelta = timeDelta;
force = steeringBehaviours.calculate();
SteeringBehaviours.checkNaN(force);
Vector3 newAcceleration = force / Mass;
if (timeDelta > 0)
{
smoothRate = Utilities.Clip(9 * timeDelta, 0.15f, 0.4f) / 2.0f;
Utilities.BlendIntoAccumulator(smoothRate, newAcceleration, ref acceleration);
}
velocity += acceleration * timeDelta;
float speed = velocity.Length();
if (speed > maxSpeed)
{
velocity.Normalize();
velocity *= maxSpeed;
}
Position += velocity * timeDelta;
// the length of this global-upward-pointing vector controls the vehicle's
// tendency to right itself as it is rolled over from turning acceleration
Vector3 globalUp = new Vector3(0, 0.2f, 0);
// acceleration points toward the center of local path curvature, the
// length determines how much the vehicle will roll while turning
Vector3 accelUp = acceleration * 0.05f;
// combined banking, sum of UP due to turning and global UP
Vector3 bankUp = accelUp + globalUp;
// blend bankUp into vehicle's UP basis vector
smoothRate = timeDelta * 3;
Vector3 tempUp = Up;
Utilities.BlendIntoAccumulator(smoothRate, bankUp, ref tempUp);
Up = tempUp;
Up.Normalize();
if (speed > 0.0001f)
{
Look = velocity;
Look.Normalize();
if (Look.Equals(Right))
{
Right = Vector3.Right;
}
else
{
Right = Vector3.Cross(Look, Up);
Right.Normalize();
SteeringBehaviours.checkNaN(ref Right, Vector3.Right);
Up = Vector3.Cross(Right, Look);
Up.Normalize();
SteeringBehaviours.checkNaN(ref Up, Vector3.Up);
}
// Apply damping
velocity *= 0.99f;
}
if (Look != basis)
{
float angle = (float)Math.Acos(Vector3.Dot(basis, Look));
Vector3 axis = Vector3.Cross(basis, Look);
quaternion = Quaternion.CreateFromAxisAngle(axis, angle);
quaternion.Normalize();
worldTransform.Up = Up;
worldTransform.Forward = Look;
worldTransform.Right = Right;
worldTransform = Matrix.CreateWorld(Position, Look, Up);
checkNan(worldTransform);
}
else
{
worldTransform = Matrix.CreateTranslation(Position);
}
drawAxis = false;
}
