A library to test web frameworks by rendering pong

EXAMPLE

import {setup, CollisionName} from "pong-renderer";

setup().then(({constants, onRender, onCollision}) => {
    const {canvasWidth, canvasHeight, ballRadius, paddleWidth, paddleHeight} = constants;

    //Render the items in the middle of the screen (without helper)
    //Real-world would have this in a requestAnimationFrame cycle
    //With the dynamic object positions
    onRender({
        ball: {x: canvasWidth/2, y: canvasHeight/2},
        paddle1: {x: paddleWidth/2, y: canvasHeight/2},
        paddle2: {x: canvasWidth - (paddleWidth/2), y: canvasHeight/2},
    });

    //Real-world would have this based on proper collision detection
    //Some browsers requires a user gesture before playing audio
    window.onclick = () => onCollision(CollisionName.LEFT_WALL);
});

API

There are only two exported functions, setup() and a little getCenterPositions() helper.

It's probably easiest to see how to use them from these Typescript definitions:

const setup = (options: SetupOptions) => Promise<SetupResult>;
const getCenterPositions = (constants: Constants) => GameObjectPositions;

interface SetupOptions {
    constants?: Constants;
    handleController: ControllerHandler;
}
interface SetupResult {
    constants: Readonly<Constants>;
    onRender: (gameObjects: GameObjectPositions) => void;
    onCollision: (collisionName: CollisionName | string) => void;
}
interface GameObjectPositions {
    ball: Position;
    paddle1: Position;
    paddle2: Position;
}

export interface Position {
    x: number;
    y: number;
}

export type ControllerHandler = (value:ControllerValue) => void;

export enum ControllerValue {
    UP = "up",
    DOWN = "down",
    NEUTRAL = "neutral",
    SERVE = "serve"
}

export interface Constants {
    ballRadius: number; 
    ballSpeed: number; 
    paddleWidth: number; 
    paddleHeight: number; 
    paddleMargin: number; 
    canvasWidth: number; 
    canvasHeight: number;
}

In plain English, it's pretty much:

1. call setup() with (optional) configuration options and a (mandatory) ControllerHandler
2. get back an onRender() callback that you use to render (hint: call it in a rAF cycle) and onCollision that you use when the ball and paddle collide. You also get back the final constants (i.e. in the case where you didn't override them)

Controls

The keyboard bindings are currently hardcoded in order to allow a simpler API. This may change in the future:

• Serve Ball: Space
• Move Paddle: up/w or down/s

Sounds and graphics

Same idea - hard coded to make it simple. Could be swapable in the future, but whatever.

Coordinates

Positions are the center of the object. For example, setting the ball position to canvasHeight/2 and the paddle position to canvasHeight/2 will place it vertically center, regardless of the different heights of those objects

Similarly, to place the paddles flush against the side of the screen, it's paddleWidth/2 on the left and canvasWidth - (paddleWidth/2) on the right

History

Originally written as part of FRPong