/// <summary>
        /// Initializes a new instance of FirstPersonCamera.
        /// </summary>
        public FirstPersonCamera(float accelerationMagnitude, float rotationSpeed, float velocityDecayRate)
        {
            inputState = new InputState();

            this.accelerationMagnitude = accelerationMagnitude;
            this.rotationSpeed = rotationSpeed;
            this.velocityDecayRate = velocityDecayRate;
        }
        /// <summary>
        /// Creates a new message box and addes usage information to the beginning of the message.
        /// </summary>
        /// <param name="message">The string to display</param>
        /// <param name="backgroundContentName">The name (without extension) of the texture content to use as 
        /// the background of this message box.</param>
        public MessageBoxScreen(string message, string backgroundContentName)
        {
            this.backgroundContentName = backgroundContentName;

            const string usageText = "\nA = Ok" + "\nB = Cancel";
            this.message = message + usageText;

            IsPopup = true;

            TransitionOnTime = TimeSpan.FromSeconds(0.2);
            TransitionOffTime = TimeSpan.FromSeconds(0.2);

            inputState = new InputState();
        }
 /// <summary>
 /// Initializes a new instance of FirstPersonCamera.
 /// </summary>
 public FirstPersonCamera()
 {
     inputState = new InputState();
 }