/Solution-RCD6/ASPItalia.ModelVirtualCasting.NinjaBraa/NinjBraa/NinjBraa/Elements/General/StraightLineMovementComponent.cs

#region File Description

//-----------------------------------------------------------------------------

// StraightLineMovementComponent.cs

//

// Microsoft XNA Community Game Platform

// Copyright (C) Microsoft Corporation. All rights reserved.

//-----------------------------------------------------------------------------

#endregion



#region Using Statements





using System;

using System.Collections.Generic;

using System.Text;

using Microsoft.Xna.Framework;

using Microsoft.Xna.Framework.Graphics;





#endregion



namespace NinjaBra

{

    /// <summary>

    /// A component that moves between two points in a straight line at a specified speed.

    /// </summary>

    class StraightLineMovementComponent : AnimatedComponent

    {

        #region Fields/Properties/Events



        /// <summary>

        /// Velocity in pixels per second.

        /// </summary>

        Vector2 velocity;



        // Distance remaining until the destination is reached.

        float distance;



        bool isEventFired = true;



        /// <summary>

        /// An event fired once the component has reached its destination. This event will only fire once

        /// per call of <see cref="Move"/>.

        /// </summary>

        public event EventHandler FinishedMoving;



        /// <summary>

        /// Component's center, which is also it's position.

        /// </summary>

        public override Vector2 Center

        {

            get

            {

                return Position;

            }

        }



        #endregion



        #region Initialization





        /// <summary>

        /// Creates a new instance of the straight line motion game component.

        /// </summary>

        /// <param name="game">Associated game object.</param>

        /// <param name="gameScreen">Game screen where the component will be presented.</param>

        /// <param name="texture">Texture asset which represents the component.</param>

        public StraightLineMovementComponent(Game game, GameplayScreen gameScreen, Texture2D texture)

            : base(game, gameScreen, texture)

        {

        }



        /// <summary>

        /// Creates a new instance of the straight line motion game component.

        /// </summary>

        /// <param name="game">Associated game object.</param>

        /// <param name="gameScreen">Game screen where the component will be presented.</param>

        /// <param name="animation">Animation object which represents the component.</param>

        public StraightLineMovementComponent(Game game, GameplayScreen gameScreen, Animation animation)

            : base(game, gameScreen, animation)

        {

        }





        #endregion



        #region Update





        /// <summary>

        /// Updates the component's position.

        /// </summary>

        /// <param name="gameTime">Game time information.</param>

        public override void Update(GameTime gameTime)

        {

            base.Update(gameTime);



            float elapsedSeconds = (float)gameTime.ElapsedGameTime.TotalSeconds;



            Vector2 movement = velocity * elapsedSeconds;

            Position += movement;

            distance -= movement.Length();



            // Check whether the event generated by reaching the destination needs to be fired.

            if (!isEventFired && distance <= 0)

            {

                // Move back in case we moved too much

                velocity.Normalize();

                Position += velocity * distance;



                // Fire the event and stop moving

                if (FinishedMoving != null)

                {

                    FinishedMoving(this, EventArgs.Empty);

                }



                isEventFired = true;

                velocity = Vector2.Zero;

            }

        }





        #endregion



        #region Rendering





        /// <summary>

        /// Renders the component.

        /// </summary>

        /// <param name="gameTime">Game time information.</param>

        public override void Draw(GameTime gameTime)

        {

            spriteBatch.Begin();



            animation.Draw(spriteBatch, Position, 0, VisualCenter, 1, SpriteEffects.None, 0);



            spriteBatch.End();

        }





        #endregion



        #region Public Methods





        /// <summary>

        /// Causes the component to move from a specified location, in a straight, to another location.

        /// </summary>

        /// <param name="velocity">Movement velocity in pixels per second. Must be a positive number.</param>

        /// <param name="initialPosition">Component's starting point.</param>

        /// <param name="destination">The component's movement destination.</param>

        public void Move(float velocity, Vector2 initialPosition, Vector2 destination)

        {

            if (velocity <= 0)

            {

                throw new ArgumentOutOfRangeException("velocity", "Argument must be greater than 0.");

            }



            Vector2 toDestinationVector = (destination - initialPosition);

            Vector2 velocityUnitVector = toDestinationVector;

            velocityUnitVector.Normalize();



            this.velocity = velocityUnitVector * velocity;

            this.distance = toDestinationVector.Length();

            Position = initialPosition;

            isEventFired = false;

        }



        /// <summary>

        /// Causes the component to move from a specified location, in a straight, to another location.

        /// </summary>

        /// <param name="time">The time it should take the component to reach its destination. Must be a positive

        /// time span.</param>

        /// <param name="initialPosition">Component's starting point.</param>

        /// <param name="destination">The component's movement destination.</param>

        public void Move(TimeSpan time, Vector2 initialPosition, Vector2 destination)

        {

            if (time <= TimeSpan.Zero)

            {

                throw new ArgumentOutOfRangeException("time", "Argument must be a positive time span.");

            }



            Vector2 toDestinationVector = (destination - initialPosition);

            float distance = toDestinationVector.Length();



            float requiredVelocity = distance / (float)time.TotalSeconds;



            Move(requiredVelocity, initialPosition, destination);

        }





        #endregion

    }

}