encompass-cs-docs/content/concepts/world.md

title	date	weight
World	2019-05-22T12:51:08-07:00	100

World is the pie crust that contains all the delicious Encompass ingredients together.

The World's Update function drives the simulation and should be controlled from your engine's update loop.

The World's Draw function tells the Renderers to draw the scene.

In MonoGame, the game loop looks something like this:

using Encompass;
using Microsoft.Xna.Framework;

public class MyGame : Game
{
    private World world;
    SpriteBatch spriteBatch;

    RenderTarget2D gameRenderTarget;
    RenderTarget2D levelBrowserRenderTarget;
    RenderTarget2D uiRenderTarget;

    ...

    /// <summary>
    /// Allows the game to run logic such as updating the world,
    /// checking for collisions, gathering input, and playing audio.
    /// </summary>
    /// <param name="gameTime">Provides a snapshot of timing values.</param>
    protected override void Update(GameTime gameTime)
    {
        if (GamePad.GetState(Microsoft.Xna.Framework.PlayerIndex.One).Buttons.Back == ButtonState.Pressed || Keyboard.GetState().IsKeyDown(Keys.Escape))
            Exit();

        world.Update(gameTime.ElapsedGameTime.TotalSeconds);

        base.Update(gameTime);
    }

    /// <summary>
    /// This is called when the game should draw itself.
    /// </summary>
    /// <param name="gameTime">Provides a snapshot of timing values.</param>
    protected override void Draw(GameTime gameTime)
    {
        world.Draw();

        GraphicsDevice.SetRenderTarget(null);

        spriteBatch.Begin(SpriteSortMode.Deferred, null, SamplerState.PointClamp);
        spriteBatch.Draw(gameRenderTarget, windowDimensions, Color.White);
        spriteBatch.Draw(levelBrowserRenderTarget, windowDimensions, Color.White);
        spriteBatch.Draw(uiRenderTarget, windowDimensions, Color.White);
        spriteBatch.End();

        base.Draw(gameTime);
    }
}

But you can call these methods wherever you see fit.

{{% notice tip %}} Certain Encompass projects actually have multiple separate Worlds to manage certain behaviors. This is perfectly valid and can be a great way to structure your project, but be warned that it is difficult to share information between Worlds by design. {{% /notice %}}

What's that whole dt business about?

dt stands for delta-time. Correct usage of delta-time is crucial to make sure that your game does not become frame-dependent, which is very bad. We'll talk more about frame-dependence later in the tutorial, but to briefly summarize, if your game is frame-dependent you will run into very frustrating behavior when running your game on different computer systems.

Even if you lock your game to a fixed timestep, writing your game with delta-time in mind can be the difference between changing the timestep being a one-line tweak or a weeks long hair-pulling nightmare.

That's it! Now that we have these high-level concepts down, let's build an actual, for-real game.