“Pixelfield” HTML5 prototype updated – adding wraparound effect

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Pixelfield is a series I’d like to continue until I get a modern, playable hyper casual games but in order to do this, I have to change a bit the gameplay which was launched in 2008.

The first thing I want to change is the way you control and move the player, removing the main body and only leaving the four satellites, adding the wraparound effect.

From Wikipedia: Wraparound, in video games, is a gameplay variation on the single-screen in which space is finite but unbounded; objects leaving one side of the screen immediately reappear on the opposite side, maintaining speed and trajectory. This is referred to as “wraparound”, since the top and bottom of the screen wrap around to meet, as do the left and right sides.

A famous game using this effect is Asteroids.

So, this is what I built:

Tap around the canvas and see what happens, with the wraparound effect in action.

How did I achieve this? In the laziest and cheapest way ever. There are nine copies of the main object, shifted by an amount of pixels so that when the main object is off the screen, one of its copies enters from the other side, and the wraparound effect is made.

You may say this is not an optimized way to handle this effect, as there is a lot of objects not needed in the game, but in this case, an hyper casual games with only a few objects in the game, it works like a charm and does not slow down the frame rate.

Have a look at the source code, still uncommented but easy to understand:

let game;

let gameOptions = {
    smallSquareSize: 25,
    satelliteDistance: 200,
    speedScale: 0.01,
    friction: 0.95,
    squareRotation: 0.02
}

window.onload = function() {
    let gameConfig = {
        type: Phaser.AUTO,
        backgroundColor: 0x222222,
        scale: {
            mode: Phaser.Scale.FIT,
            autoCenter: Phaser.Scale.CENTER_BOTH,
            parent: "thegame",
            width: 750,
            height: 1334
        },
        scene: playGame
    }
    game = new Phaser.Game(gameConfig);
    window.focus();
}

class playGame extends Phaser.Scene {
    constructor() {
        super("PlayGame");
    }
    create() {
        this.elasticsGraphics = this.add.graphics();
        this.playerData = {
            x: game.config.width / 2,
            y: game.config.height / 2,
            rotation: 0
        }
        let smallSquareGraphics = this.make.graphics();
        smallSquareGraphics.fillStyle(0xff0000, 1);
        smallSquareGraphics.fillRect(0, 0, gameOptions.smallSquareSize, gameOptions.smallSquareSize);
        smallSquareGraphics.generateTexture("smallSquare", gameOptions.smallSquareSize, gameOptions.smallSquareSize);
        this.smallSquares = [];
        for(let i = 0; i < 36; i ++) {
            this.smallSquares.push({
                sprite: this.add.sprite(game.config.width / 2, game.config.height / 2, "smallSquare"),
                xSpeed: 0,
                ySpeed: 0
            })
        }
        this.squarePositions = [];
        for(let i = 0; i < 4; i ++) {
            let perfectX = this.playerData.x + gameOptions.satelliteDistance * Math.cos(this.playerData.rotation + i * Math.PI / 2 + Math.PI / 4);
            let perfectY = this.playerData.y + gameOptions.satelliteDistance * Math.sin(this.playerData.rotation + i * Math.PI / 2 + Math.PI / 4);
            this.squarePositions.push({
                x: perfectX,
                y: perfectY,
                xSpeed: 0,
                ySpeed: 0
            })
        }
        this.input.on("pointerdown", this.moveSquare, this);
    }
    moveSquare(e) {
        this.playerData.x = e.x;
        this.playerData.y = e.y;
    }
    update() {
        this.elasticsGraphics.clear();
        this.elasticsGraphics.lineStyle(1, 0x00ff00);
        this.playerData.rotation += gameOptions.squareRotation;
        for(let i = 0; i < 4; i ++) {
            let perfectX = this.playerData.x + gameOptions.satelliteDistance * Math.cos(this.playerData.rotation + i * Math.PI / 2 + Math.PI / 4);
            let perfectY = this.playerData.y + gameOptions.satelliteDistance * Math.sin(this.playerData.rotation + i * Math.PI / 2 + Math.PI / 4);
            let distanceX = (perfectX - this.squarePositions[i].x) * gameOptions.speedScale;
            let distanceY = (perfectY - this.squarePositions[i].y) * gameOptions.speedScale;
            this.squarePositions[i].xSpeed += distanceX;
            this.squarePositions[i].ySpeed += distanceY;
            this.squarePositions[i].xSpeed *= gameOptions.friction;
            this.squarePositions[i].ySpeed *= gameOptions.friction;
            this.squarePositions[i].x += this.squarePositions[i].xSpeed;
            this.squarePositions[i].y += this.squarePositions[i].ySpeed;
        }
        for(let i = 0; i < 36; i ++) {
            this.smallSquares[i].sprite.rotation = this.playerData.rotation;
            let temp = Math.floor(i / 4);
            let deltaX = game.config.width * (temp % 3 == 0 ? 1 : (temp % 3 == 2 ? -1 : 0));
            let deltaY = game.config.height * (Math.floor(temp / 3) == 0 ? -1 : (Math.floor(temp / 3) == 2 ? 1 : 0));
            this.smallSquares[i].sprite.x = this.squarePositions[i % 4].x + deltaX;
            this.smallSquares[i].sprite.y = this.squarePositions[i % 4].y + deltaY;
            this.elasticsGraphics.lineBetween(this.playerData.x + deltaX, this.playerData.y +deltaY, this.smallSquares[i].sprite.x, this.smallSquares[i].sprite.y);
        }
    }
}

Now we just have to add some stuff to collect and some other stuff to avoid, and we could have a completely working game in about 100 lines of code.

Download the source code and enjoy.

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