Getting Started

This documentation mainly covers Astro, for a guide on how to use Astro’s language of choice, Wren, visit the Wren website and the Wren section. To launch an Astro project, you need the runtime (Astro.exe) and at least one Wren file named data/game/init.wren that tells the engine where and how to start execution.

In brief, you want

• All of your resources inside data/.
• All of your .wren source files in data/game.
• A file named data/game/init.wren that tells Astro how to start.

Runtime

You may either build the C runtime yourself or download a binary if their available. The runtime is responsible for the Wren virtual machine, asset compiling, and error bindings to the engine functionality.

Downloads

Astro Standard Library

The Astro standard library is automatically imported in every file Astro loads. This means that anywhere in your game you don’t need to import anything Astro defines, simply use the method. For example, you don’t need to import the keyboard, just use it via something like Keyboard.key(Keyboard.KEY_LEFT). Check the API Reference for a complete list of all classes and methods in said classes.

data/game/init.wren

The init.wren file is the “entry point” of your game. It must contain the two variables renderer_config and start_level. start_level is an instance of Level that the engine will use as the entry point. renderer_config must be a map containing specific keys.

import "Game" for Game

var renderer_config = {
    "window_title": "Game",
    "window_width": 800,
    "window_height": 600,
    "fullscreen": false,
    "msaa": Renderer.MSAA_8X,
    "screen_mode": Renderer.SCREEN_MODE_TRIPLE_BUFFER,
    "filter_type": Renderer.FILTER_TYPE_NEAREST
}

var window_icon = "data/logo.png"
var minimum_load_time = 3

var start_level = Game.new()

There are two other (optional) variables you may set in this file: window_icon and minimum_load_time. window_icon should specify an image file which Astro will set as the window icon, and minimum_load_time will be the minimum amount of time the loading screen (see: Loading Screen) will be displayed.

As you can see, the Renderer class provides values to use for msaa, screen_mode, and filter_type. Check config for details on each of the map’s keys and expected values, but the above example has all required map keys. The level instance you pass will eventually have its create method called once the engine has fully initialized.

When the init.wren file is loaded into Astro most of the engine is not yet initialized - in particular anything that handles user input, the window and renderer, and all the user assets. You may use things like INI or File to read saved settings, but not much past that.

Loading Screen

Astro will display a small (800x450) image while the game compiles and loads the asset file/initializes the renderer. By default this will show an Astro Engine banner, but you may specify your own loading screen image by placing an image at data/_loading.png. By default that image is displayed for at least 3 seconds (adjustable in the init.wren file as seen above) so this is a good place to put promo materials.