MonoGame.Extended/Source/Demos/StarWarrior/Systems/EnemyShooterSystem.cs

// Original code dervied from:
// https://github.com/thelinuxlich/starwarrior_CSharp/blob/master/StarWarrior/StarWarrior/Systems/EnemyShooterSystem.cs

// --------------------------------------------------------------------------------------------------------------------
// <copyright file="EnemyShooterSystem.cs" company="GAMADU.COM">
//     Copyright © 2013 GAMADU.COM. All rights reserved.
//
//     Redistribution and use in source and binary forms, with or without modification, are
//     permitted provided that the following conditions are met:
//
//        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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//     The views and conclusions contained in the software and documentation are those of the
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// </copyright>
// <summary>
//   The enemy shooter system.

// </summary>
// --------------------------------------------------------------------------------------------------------------------

using Microsoft.Xna.Framework;
using MonoGame.Extended;
using MonoGame.Extended.Entities;
using MonoGame.Extended.Entities.Systems;
using StarWarrior.Components;

namespace StarWarrior.Systems
{
    public class EnemyShooterSystem : EntityProcessingSystem
    {
        private readonly EntityFactory _entityFactory;

        public EnemyShooterSystem(EntityFactory entityFactory) 
            : base(Aspect.All(typeof(WeaponComponent), typeof(Transform2), typeof(EnemyComponent)))
        {
            _entityFactory = entityFactory;
        }

        public override void Initialize(IComponentMapperService mapperService)
        {
        }

        public override void Process(GameTime gameTime, int entityId)
        {
            var entity = GetEntity(entityId);
            var transform = entity.Get<Transform2>();
            var weapon = entity.Get<WeaponComponent>();

            weapon.ShootTimerDelay += gameTime.ElapsedGameTime;
            if (weapon.ShootTimerDelay <= weapon.ShootDelay)
                return;
            weapon.ShootTimerDelay -= weapon.ShootDelay;

            var missile = _entityFactory.CreateMissile();
            var missileTransform = missile.Get<Transform2>();

            var worldPosition = transform.WorldPosition;
            missileTransform.Position = worldPosition + new Vector2(0, 20);

            var missilePhysics = missile.Get<PhysicsComponent>();

            missilePhysics.Speed = -0.5f;
            missilePhysics.Angle = 270;
        }
    }
}