MonoGame.Samples/StarWarrior/Core/Systems/EnemyShipMovementSystem.cs

#region File description

// --------------------------------------------------------------------------------------------------------------------
// <copyright file="EnemyShipMovementSystem.cs" company="GAMADU.COM">
//     Copyright © 2013 GAMADU.COM. All rights reserved.
//
//     Redistribution and use in source and binary forms, with or without modification, are
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//
//        1. Redistributions of source code must retain the above copyright notice, this list of
//           conditions and the following disclaimer.
//
//        2. Redistributions in binary form must reproduce the above copyright notice, this list
//           of conditions and the following disclaimer in the documentation and/or other materials
//           provided with the distribution.
//
//     THIS SOFTWARE IS PROVIDED BY GAMADU.COM 'AS IS' AND ANY EXPRESS OR IMPLIED
//     WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
//     FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GAMADU.COM OR
//     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
//     CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
//     SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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// </copyright>
// <summary>
//   The enemy ship movement system.
// </summary>
// --------------------------------------------------------------------------------------------------------------------
#endregion File description

namespace StarWarrior.Systems
{
    #region Using statements

    using Artemis;
    using Artemis.Attributes;
    using Artemis.Manager;
    using Artemis.System;

    using Microsoft.Xna.Framework.Graphics;

    using StarWarrior.Components;

    #endregion

    /// <summary>The enemy ship movement system.</summary>
    [ArtemisEntitySystem(GameLoopType = GameLoopType.Update, Layer = 0)]
    internal class EnemyShipMovementSystem : EntityProcessingSystem
    {
        /// <summary>The sprite batch.</summary>
        private SpriteBatch spriteBatch;

        /// <summary>Initializes a new instance of the <see cref="EnemyShipMovementSystem" /> class.</summary>
        public EnemyShipMovementSystem()
            : base(Aspect.All(typeof(TransformComponent), typeof(VelocityComponent), typeof(EnemyComponent)))
        {
        }

        /// <summary>Override to implement code that gets executed when systems are initialized.</summary>
        public override void LoadContent()
        {
            this.spriteBatch = BlackBoard.GetEntry<SpriteBatch>("SpriteBatch");
        }

        /// <summary>Processes the specified entity.</summary>
        /// <param name="entity">The entity.</param>
        public override void Process(Entity entity)
        {
            var transformComponent = entity.GetComponent<TransformComponent>();
            if (transformComponent != null && (transformComponent.X < 0 || transformComponent.X > this.spriteBatch.GraphicsDevice.Viewport.Width))
            {
                entity.GetComponent<VelocityComponent>().AddAngle(180);
            }
        }
    }
}