PongFE/PongFE/Engines/MotionEngine.cs

using Encompass;
using PongFE.Components;
using PongFE.Messages;

namespace PongFE.Engines
{
    [Reads(typeof(PositionComponent))]
    [Receives(typeof(MotionMessage))]
    [Writes(typeof(PositionComponent))]
    public class MotionEngine : Engine
    {
        public override void Update(double dt)
        {
            foreach (ref readonly var motionMessage in ReadMessages<MotionMessage>())
            {
                if (HasComponent<PositionComponent>(motionMessage.Entity))
                {
                    ref readonly var positionComponent = ref GetComponent<PositionComponent>(motionMessage.Entity);
                    var newPosition = positionComponent.Position + motionMessage.Movement;
                    SetComponent(motionMessage.Entity, new PositionComponent(newPosition));
                }
            }
        }
    }
}