sneak/Shared/ShmupWorld.cs

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

namespace SemiColinGames {
  public sealed class ShmupWorld : IWorld {
    public struct ShmupPlayer {
      // Center of player sprite.
      public Vector2 Position;
    }

    public ShmupPlayer Player;

    public ShmupWorld() {
      Player = new ShmupPlayer();
    }

    ~ShmupWorld() {
      Dispose();
    }

    public void Dispose() {
      GC.SuppressFinalize(this);
    }

    public void Update(float modelTime, History<Input> input) {
      float speed = 150f;
      Vector2 motion = Vector2.Multiply(input[0].Motion, modelTime * speed);
      Player.Position = Vector2.Add(Player.Position, motion);
    }
  }
}