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Pockety API

Scene API

Entity API

Pockety is a minimalistic game engine, and as such it keeps its API quite minimal as well.

The engine lifecycle is the following:

1. Page Load

As the page is loaded, the StartGame function inside the game.js file is called. In this function, we expect to implement the entirety of our game loop.

const StartGame = async () => {
	// First, a new instance of the engine must be initialised
	// this method accepts 2 arguments: width and height.
	// if they are set to "auto", they will expand to fit the page
  let pockety = new Pockety("auto", 300);
  
}

2. Game Loop

The game can then be started by calling the Run(scene) function.

At this point the engine will perform the following operations:

// first the engine will call the internal _start function
_start = (startingScene) => {
    this.StopAllAudio();

    this.startTimeMS = Date.now();

		// the LoadScene() function, not only loads the entities in the activeScene
		// but it also calls the Start() function in each Entity in the scene
    this.LoadScene(startingScene);

    this._gameLoop();
  };

// then the _gameLoop starts. This function is called every Frame
_gameLoop = () => {
	// if the engine has Quit, we don't run the game
  if (!this.isRunning) return;
	
	// we calculate the delta time (time between Frame renders)
  this.deltaTime = (Date.now() - this.startTimeMS) / 1000;

	// if there is a touch or click, we run the OnTouch() function
  if (this.touching) this.OnTouch();

	// we call the Update() function in each Entity in the scene
  this.activeScene.Update(this.deltaTime);
  // then we run collision detection, this notifies each colliding Entity
  this._collisionDetection();
  // finally, we draw everything on the canvas
  this._render(this.deltaTime);

	// here we update the last pressed keys
  this.lastKeys = this.keysPressed.slice(0);

	// we then reset the start time for delta time calculations
  this.startTimeMS = Date.now();
  // and finally, we request the next frame to the canvas
  requestAnimationFrame(this._gameLoop);
};

// the Quit function simply stops the engine from running the game
Quit = () => {
  this.isRunning = false;
  this.StopAllAudio();
};