World.cs

using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;

namespace PrototypeRPG.Traits
{
	public class World
	{
		public const int TickTimestep = 40;

		public SpriteBatch SpriteBatch { get; private set; }
		public List<Actor> Actors = new List<Actor>();

		public int TotalTickCount { get { return TickCount + TickRenderCount; } }
		public int TickCount { get; private set; }
		public int TickRenderCount { get; private set; }

		int lastTickDelta = 0;

		public World(SpriteBatch spriteBatch) {	SpriteBatch = spriteBatch; }

		public void Tick(GameTime gameTime)
		{
			if (gameTime.ElapsedGameTime >= TickTimestep)
			{
				InnerTick();
				lastTickDelta = 0;
			}
			else
				lastTickDelta++;
		}

		void InnerTick()
		{
			TickCount++;

			foreach (var actor in Actors)
			{
				foreach (var trait in actor.TraitsImplementing<ITick>())
					trait.Tick(actor);

			}
		}

		public void TickRender()
		{
			TickRenderCount++;

			foreach (var actor in Actors)
				foreach (var trait in actor.TraitsImplementing<ITickRender>())
					trait.TickRender(actor, SpriteBatch);
		}
	
		public Actor CreateActor(params ITrait[] traits)
		{
			var newActor = new Actor();

			foreach (var trait in traits)
				newActor.AddTrait(trait);

			Actors.Add(newActor);

			return newActor;
		}
	}
}