/// <summary>
        /// Changes character position.
        /// </summary>
        /// <param name="distance">The distance traveled by character.</param>
        public void Move(double distance)
        {
            Position = new Point3D(
                Position.X + System.Math.Sin(HAngle * Math.PI / 180) * distance,
                Position.Y + 0,
                Position.Z + System.Math.Cos(HAngle * Math.PI / 180) * distance);
        }

/// <summary>
        /// Changes character look direction.
        /// </summary>
        /// <param name="angle">The horizontal angle at which the character looks now.</param>
        public void Turn(double hAngle)
        {
            // It is not distance of movement. It is just accessory value to calculate the look direction vector.
            double distanceToPointToLook = 1;

            HAngle += hAngle;
            LookDirection = new Vector3D(
                System.Math.Sin(HAngle * Math.PI / 180) * distanceToPointToLook,
                0,
                System.Math.Cos(HAngle * Math.PI / 180) * distanceToPointToLook);
        }

private void Window_KeyDown(object sender, KeyEventArgs e)
        {
            switch (e.Key)
            {
                case Key.Up:
                    player.Move(1);
                    playerCamera.BeginAnimation(
                        PerspectiveCamera.PositionProperty,
                        new System.Windows.Media.Animation.Point3DAnimation(
                            player.Position,
                            new Duration(new TimeSpan(0, 0, 0, 0, 500))));
                    break;
                case Key.Down:
                    player.Move(-1);
                    playerCamera.BeginAnimation(
                        PerspectiveCamera.PositionProperty,
                        new System.Windows.Media.Animation.Point3DAnimation(
                            player.Position,
                            new Duration(new TimeSpan(0, 0, 0, 0, 500))));
                    break;
                case Key.Left:
                    player.Turn(90);
                    playerCamera.BeginAnimation(
                        PerspectiveCamera.LookDirectionProperty,
                        new System.Windows.Media.Animation.Vector3DAnimation(
                            player.LookDirection,
                            new Duration(new TimeSpan(0, 0, 0, 0, 500))));
                    break;
                case Key.Right:
                    player.Turn(-90);
                    playerCamera.BeginAnimation(
                        PerspectiveCamera.LookDirectionProperty,
                        new System.Windows.Media.Animation.Vector3DAnimation(
                            player.LookDirection,
                            new Duration(new TimeSpan(0, 0, 0, 0, 500))));
                    break;
                default:
                    break;
            }
        }