Gorg - Gorgeours Game Engine

Gorg is a very basic 2D game engine. Out of the box you get very small building blocks that can't do too much on their own, but combined and enhanced you can build literally anything you want. Let's take a closer look:

World

Everything starts with a World.

import { World } from 'gorg';

const width = 640;
const height = 480;
const fps = 60;

const world = new World([], fps, width, height);

world.renderer.appendTo(document.querySelector('#app'));

World keeps track of Scenes, viewport width and height and keeps the game loop running with a set amount of frames per second.

Scene

Having a world is pretty cool already, but without a scene, you can't even run it. You can think of scenes as a level in your game: during the game loop, your player will travel from scene to scene.

- import { World } from 'gorg';
+ import { World, Scene } from 'gorg';

const width = 640;
const height = 480;
const fps = 60;

const world = new World([], fps, width, height);

world.renderer.appendTo(document.querySelector('#app'));

+ const scene = new Scene('main', []);

+ world.addScenes(scene);

Now that we have a scene (even though it's empty), we can start our game:

world.start('main');

Camera

By default, scenes are completely empty. If you want scene to render something on the screen, it needs a camera. Cameras are a special case of the GameObject (that we will talk about later) and they are responsible for making other game objects visible in the world.

- import { World, Scene } from 'gorg';
+ import { World, Scene, OrthographicCamera } from 'gorg';

const width = 640;
const height = 480;
const fps = 60;

const world = new World([], fps, width, height);

world.renderer.appendTo(document.querySelector('#app'));

const scene = new Scene('main', []);

+ const camera = new OrthographicCamera('camera');

+ scene.addObjects(camera);

world.addScenes(scene);

world.start('main');

GameObject

Okay, so now we have at least something going on on the screen. Let's add some GameObjects. Game objects are the main part of your game: player character is a GameObject, their dog companion is a GameObject, treasures in the dungeon that they will find together are GameObject, the possibilities are endless! But let's start with something a little bit more basic.

- import { World, Scene, OrthographicCamera } from 'gorg';
+ import { World, Scene, OrthographicCamera, GameObject } from 'gorg';

const width = 640;
const height = 480;
const fps = 60;

const world = new World([], fps, width, height);

world.renderer.appendTo(document.querySelector('#app'));

const scene = new Scene('main', []);

const camera = new OrthographicCamera('camera');

+ const rectangle = new GameObject('rectangle');

- scene.addObjects(camera);
+ scene.addObjects([camera, rectangle]);

world.addScenes(scene);

world.start('main');

Components

Well, just adding GameObjects to the scene was a little underwhelming, right? GameObject on their own are not very interesting, their primary use-case is to store components.

Components are what defines GameObject behavior. There are four types of components: state, transform, update and render. Every GameObject by default gets one state and transform component and can have multiple render and update components.

• Transform component keeps GameObject position, rotation and scale information.

• State component is a basic key value storage for any information that you want to share between GameObject components.

• Render components allow you to tell the World how to draw GameObject on the screen.

// file:./RectRendererComponent.js

import Vector2d from 'gorg';

export class RectRendererComponent {
  constructor(width, height, fillStyle) {
    this.width = width;
    this.height = height;
    this.fillStyle = fillStyle;
  }

  render(world, scene, gameObject, camera, remainder) {
    const { renderer } = world;

    const centerX = this.width / 2;
    const centerY = this.height / 2;

    renderer.context.fillStyle = this.fillStyle;
    renderer.context.fillRect(-centerX, -centerY, this.width, this.height);
  }
}

• Update components allow you to change GameObject state before any render component will have a chance to draw it on the screen:

// file:./RotateUpdaterComponent.js

export class RotateUpdaterComponent {
  constructor(angle) {
    this.angle = angle;
  }

  update(world, scene, gameObject, deltaTime) {
    gameObject.components.transform.rotateByDeg(this.angle * (1 / deltaTime));
  }
}

All Together Now

Okay, let's wrap up and put everything together:

import { World, Scene, OrthographicCamera, GameObject } from 'gorg';

+ import { RectRendererComponent } from './RectRendererComponent.js';
+ import { RotateUpdaterComponent } from './RotateUpdaterComponent.js';

const width = 640;
const height = 480;
const fps = 60;

const world = new World([], fps, width, height);

world.renderer.appendTo(document.querySelector('#app'));

const scene = new Scene('main', []);

const camera = new OrthographicCamera('camera');

- const rectangle = new GameObject('rectangle');
+ const rectangle = new GameObject('rectangle', {
+   update: [new RotateUpdaterComponent(10)],
+   render: [new RectRendererComponent(100, 50, 'cyan')],
+ });

scene.addObjects([camera, rectangle]);

world.addScenes(scene);

world.start('main');

If everything went according to plan, this is what you should see on your screen: