Destroy platforms with style in your HTML5 platformers powered by Phaser using particle emitters and emit zones

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When building a platform game, sometimes you need some platforms to be destroyed.

In DROP’d game, platforms need to be destroyed to make the player fall down and land on next platforms, so destroying a platform is one of the most important parts of the game.

I could just make a platform disappear, or maybe fade it out, but what about destroying it in pieces?

Have a look:

Tap to destroy green platform, and try to land on yellow platform. If you miss it, it’s game over. But most of all, look how I am destroying a platform.

A particle explosion, with an emit zone which matches the platform we are going to destroy. Yes, that easy.

Look at the source code, I highlighted and commented the code added since the first part of the prototype:

let game;
let gameOptions = {
    firstPlatformPosition: 2 / 10,
    gameGravity: 1700,
    platformHorizontalSpeedRange: [250, 400],
    platformLengthRange: [120, 300],
    platformVerticalDistanceRange: [150, 250]
}
window.onload = function() {
    let gameConfig = {
        type: Phaser.AUTO,
        backgroundColor:0x0c1445,
        scale: {
            mode: Phaser.Scale.FIT,
            autoCenter: Phaser.Scale.CENTER_BOTH,
            parent: "thegame",
            width: 750,
            height: 1334
        },
        physics: {
            default: "arcade",
            arcade: {
                gravity: {
                    y: gameOptions.gameGravity
                }
            }
        },
        scene: playGame
    }
    game = new Phaser.Game(gameConfig);
    window.focus();
}
class playGame extends Phaser.Scene {
    constructor() {
        super("PlayGame");
    }
    preload() {
        this.load.image("hero", "hero.png");
        this.load.image("platform", "platform.png");

        // particle image, a 16x16 white square
        this.load.image("particle", "particle.png");
    }
    create() {
        this.platformGroup = this.physics.add.group();
        for (let i = 0; i < 10; i ++) {
            this.addPlatform(i == 0);
        }
        this.hero = this.physics.add.sprite(game.config.width / 2, 0, "hero");
        this.hero.setFrictionX(1);
        this.canDestroy = false;
        this.cameras.main.startFollow(this.hero, true, 0, 0.5, 0, - (game.config.height / 2 - game.config.height * gameOptions.firstPlatformPosition));
        this.input.on("pointerdown", this.destroyPlatform, this);

        // creation of the particle emitter
        this.emitter = this.add.particles("particle").createEmitter({

            // each particle starts at full scale and shrinks down until it disappears
            scale: {
                start: 1,
                end: 0
            },

            // each particle has a random speed from zero (no speed) to 200 pixels per second
            speed: {
                min: 0,
                max: 200
            },

            // the emitter is not active at the moment, this means no particles are emitted
            active: false,

            // each particle has a 500 milliseconds lifespan
            lifespan: 500,

            // the emitter can fire 50 particles simultaneously
            quantity: 50
        });
    }
    addPlatform(isFirstPlatform) {
        let platform = this.platformGroup.create(game.config.width / 2,isFirstPlatform ? game.config.width * gameOptions.firstPlatformPosition : 0, "platform");
        platform.isHeroOnIt = false;
        platform.setImmovable(true);
        platform.body.setAllowGravity(false);
        platform.setFrictionX(1);
        if(!isFirstPlatform) {
            this.positionPlatform(platform);
        }
        else {
            platform.setTint(0xffff00)
        }
        platform.assignedVelocityX = isFirstPlatform ? 0 : this.randomValue(gameOptions.platformHorizontalSpeedRange) * Phaser.Math.RND.sign();
    }
    paintSafePlatforms() {
        let floorPlatform = this.getHighestPlatform(0);
        floorPlatform.setTint(0x00ff00);
        let targetPlatform = this.getHighestPlatform(floorPlatform.y);
        targetPlatform.setTint(0xffff00);
    }
    handleCollision(hero, platform) {
        if (!platform.isHeroOnIt) {
            if (!platform.isTinted) {
                this.scene.start("PlayGame")
            }
            if (hero.x < platform.getBounds().left) {
                hero.setVelocityY(-200);
                hero.setVelocityX(-200);
                hero.angle = -45;
            }
            if (hero.x > platform.getBounds().right) {
                hero.setVelocityY(-200);
                hero.setVelocityX(200);
                hero.angle = 45;
            }
            platform.isHeroOnIt = true;
            this.paintSafePlatforms();
            this.canDestroy = true;
        }
    }
    randomValue(a) {
        return Phaser.Math.Between(a[0], a[1]);
    }
    destroyPlatform() {
        if (this.canDestroy) {
            this.canDestroy = false;
            let closestPlatform = this.physics.closest(this.hero).gameObject;

            // retrieve platform bounding box
            let platformBounds = closestPlatform.getBounds();

            // place particle emitter in the top left coordinate of the platform
            this.emitter.setPosition(platformBounds.left, platformBounds.top);

            // now the emitter is active
            this.emitter.active = true;

            // set a emit zone
            this.emitter.setEmitZone({

                // zone source is a rectangle with the same size as the platform
                source: new Phaser.Geom.Rectangle(0, 0, platformBounds.width, platformBounds.height),

                // place particles at random positions
                type: "random",

                // how many particles? 50
                quantity: 50
            });

            // explosion!
            this.emitter.explode();
            let furthestPlatform = this.physics.furthest(this.hero);
            closestPlatform.isHeroOnIt = false;
            closestPlatform.y = furthestPlatform.gameObject.y + this.randomValue(gameOptions.platformVerticalDistanceRange);
            closestPlatform.assignedVelocityX = this.randomValue(gameOptions.platformHorizontalSpeedRange) * Phaser.Math.RND.sign();
            closestPlatform.x = game.config.width / 2;
            closestPlatform.displayWidth = this.randomValue(gameOptions.platformLengthRange);
            closestPlatform.clearTint();
        }
    }
    getLowestPlatform() {
        let lowestPlatform = null;
        this.platformGroup.getChildren().forEach(function(platform) {
            lowestPlatform = Math.max(lowestPlatform, platform.y);
        });
        return lowestPlatform;
    }
    getHighestPlatform(maxHeight) {
        let highestPlatform = null;
        this.platformGroup.getChildren().forEach(function(platform) {
            if ((platform.y > maxHeight) &amp;&amp; (!highestPlatform || platform.y < highestPlatform.y)) {
                highestPlatform = platform;
            }
        });
        return highestPlatform;
    }
    positionPlatform(platform) {
        platform.y = this.getLowestPlatform() + this.randomValue(gameOptions.platformVerticalDistanceRange);
        platform.x = game.config.width / 2;
        platform.displayWidth = this.randomValue(gameOptions.platformLengthRange);
    }
    update() {
        if (this.hero.angle == 0) {
            this.physics.world.collide(this.hero, this.platformGroup, this.handleCollision, null, this);
        }
        this.platformGroup.getChildren().forEach(function(platform) {
            if (platform.y + game.config.height < this.hero.y) {
                this.scene.start("PlayGame")
            }
            let distance = Math.max(0.2, 1 - ((Math.abs(game.config.width / 2 - platform.x) / (game.config.width / 2)))) * Math.PI / 2;
            platform.setVelocityX(platform.assignedVelocityX * distance);
            if ((platform.body.velocity.x < 0 &amp;&amp; platform.getBounds().left < this.hero.displayWidth / 2) || (platform.body.velocity.x > 0 &amp;&amp; platform.getBounds().right > game.config.width - this.hero.displayWidth / 2)) {
                platform.assignedVelocityX *= -1;
            }
        }, this);
    }
}

We added a nice eye candy effect to platforms, and we still are way below 200 lines of code, thanks to the power of Phaser. Download the source code.

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// Hundreds
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