Core Systems topic

Core Systems

For convenience you have access to all core systems of Bullseye2D via global getters.

Here is an example of how you can access various subsystems from anywhere in your code that imports Bullseye2D.

class MySprite {
  var position = Vector2();

  late Image sprite;
  late Sound engineFX;

  MySprite() {
    sprite = resources.loadImage("assets/mySprite.png");
    engineFx = resources.loadSound("assets/mySound.wav");
  }

  void update() {
    if (keyboard.keyHit(KeyCodes.W)) {
      position.y -= 4;
    }
  }

  void render() {
    audio.playSound(engineFX);
    gfx.drawImage(sprite, 0, position.x, position.y);
  }
}

Backend Abstraction

Bullseye2D uses a platform abstraction layer under the hood. Each core system delegates to a platform-specific backend:

System Web Backend SDL3 Backend
Rendering WebGL2 SDL_Renderer (auto-selects GPU backend)
Audio Web Audio API SDL3_mixer
Keyboard DOM events SDL3 events
Mouse DOM events SDL3 events
Gamepad Browser Gamepad API SDL3 Gamepad API
File I/O XMLHttpRequest / Fetch dart:io
Image Loading Canvas2D / Blob SDL3_image
Font Rasterization FontFace + Canvas2D SDL3_ttf
Storage localStorage JSON file on disk

The correct backend is selected at compile time via Dart conditional imports. You never interact with backends directly -- the public API (gfx, audio, keyboard, mouse, gamepad, resources) is the same on all platforms.

Properties

accel → Accelerometer Core Systems
Provides access to the device's accelerometer data.
no setter
audio → Audio Core Systems
Manages audio playback for sounds and music.
no setter
gamepad → Gamepad Core Systems
Handles gamepad input from connected controllers.
no setter
gfx → Graphics Core Systems
The main graphics interface for rendering 2D primitives, textures, and text.
no setter
keyboard → Keyboard Core Systems
Manages keyboard input.
no setter
loader → Loader Core Systems
Manages the loading of game assets.
no setter
mouse → Mouse Core Systems
Manages mouse and touch input.
no setter
resources → ResourceManager Core Systems
Manages loading and caching of game resources like textures, fonts, and sounds.
no setter