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JavaScript Introducing JavaScript Finishing the Game Final Code Challenge

Posted by niels Lostaunau
niels Lostaunau
638 Points

is it possible to tell if the stars are overlapping from looking at the ordinates?

even though I don't see the stars overlapping it still tells "bummer"

game.js 
var game;
var player;
var platforms;
var badges;
var stars;
var poisons;
var cursors;
var jumpButton;
var scoreText;
var livesText;
var finalMessage;
var won = false;
var gameOver = false;
var currentScore = 0;
var lives = 3;
var winningScore = 100;

function createStars() {
    stars = game.add.physicsGroup();

    starCreate(425, 100, 'star');
    starCreate(315, 100, 'star');
    starCreate(175, 200, 'star');   
    starCreate(300, 250, 'star');
    starCreate(340, 290, 'star'); 
    starCreate(300, 330, 'star');
}

function createPoisons() {
    poisons = game.add.physicsGroup();

    poisonCreate(675, 275, 'poison');
    poisonCreate(450, 375, 'poison');
    poisonCreate(375, 475, 'poison');

}


function createPlatforms() {
    platforms = game.add.physicsGroup();

    platforms.create(300, 150, 'platform');
    platforms.create(400, 250, 'platform');
    platforms.create(100, 250, 'platform');
    platforms.create(500, 350, 'platform');
    platforms.create(400, 450, 'platform');
    platforms.create(300, 550, 'platform');

    platforms.setAll('body.immovable', true);
}

function starCreate(left, top, starImage) {
    var star = stars.create(left, top, starImage);
    star.animations.add('spin');
    star.animations.play('spin', 8, true);
}

function poisonCreate(left, top, poisonImage) {
    var poison = poisons.create(left, top, poisonImage);
    poison.animations.add('bubble');
    poison.animations.play('bubble', 8, true);
}

function starCollect(player, star) {
    star.kill();
    currentScore = currentScore + 20;
    if (currentScore === winningScore) {
        won = true;
    }
}

function poisonCollect(player, poison) {
    poison.kill();
    lives = lives + 1;
    if (lives === 0) {
        player.kill();
        gameOver = true;
    }
}

window.onload = function () {

    game = new Phaser.Game(800, 600, Phaser.AUTO, '', { preload: preload, create: create, update: update, render: render });

    function preload() {

        game.stage.backgroundColor = '#89889c';

        //Load images
        game.load.image('platform', 'platform.png');
        //Load spritesheets
        game.load.spritesheet('player', 'mikethefrog.png', 50, 60);
        game.load.spritesheet('poison', 'poison.png', 24, 62);
        game.load.spritesheet('star', 'star.png', 54, 52);
        game.load.spritesheet('badge', 'badge.png', 42, 54);
    }

    function create() {

        player = game.add.sprite(150, 600, 'player');
        player.animations.add('walk');
        player.anchor.setTo(0.5, 1);

        game.physics.arcade.enable(player);

        player.body.collideWorldBounds = true;
        player.body.gravity.y = 500;

        createStars();
        createPoisons();
        createPlatforms();

        cursors = game.input.keyboard.createCursorKeys();
        jumpButton = game.input.keyboard.addKey(Phaser.Keyboard.SPACEBAR);

        scoreText = game.add.text(16, 16, "SCORE: " + currentScore, { font: "24px Arial", fill: "white" });
        livesText = game.add.text(685, 16, "LIVES: " + lives, { font: "24px Arial", fill: "white" });

        finalMessage = game.add.text(game.world.centerX, 250, "", { font: "48px Arial", fill: "white" });
        finalMessage.anchor.setTo(0.5, 1);
    }

    function update() {
        scoreText.text = "SCORE: " + currentScore;
        livesText.text = "LIVES: " + lives;

        game.physics.arcade.collide(player, platforms);
        game.physics.arcade.overlap(player, stars, starCollect);
        game.physics.arcade.overlap(player, poisons, poisonCollect);

        player.body.velocity.x = 0;

        if (cursors.left.isDown) {
            player.animations.play('walk', 10, true);
            player.body.velocity.x = -350;
            player.scale.x = - 1;
        }
        else if (cursors.right.isDown) {
            player.animations.play('walk', 10, true);
            player.body.velocity.x = 350;
            player.scale.x = 1;
        }
        else {
            player.animations.stop();
        }

        if (jumpButton.isDown && (player.body.onFloor() || player.body.touching.down)) {
            player.body.velocity.y = -400;
        }
        if (won) {
            finalMessage.text = "YOU WIN!!!";
        }
        if (gameOver) {
            finalMessage.text = "GAME OVER!!!";
        }

    }

    function render() {

    }

};

2 Answers

David Evans
David Evans
10,490 Points
David Evans
David Evans
10,490 Points

Hi Niels,

With a little math it is possible to see if the stars overlap, there are a few parts you need to take into account.

function createStars() {
    stars = game.add.physicsGroup();

    starCreate(425, 100, 'star');
    starCreate(315, 100, 'star');
    starCreate(175, 200, 'star');   
    starCreate(300, 250, 'star');
    starCreate(340, 290, 'star'); 
    starCreate(300, 330, 'star');
}

This is where you're physically creating the stars. The first parameter you're passing into the starCreate function is the left position. The second parameter is the top position.

You can see this by looking at the function further down in the code:

function starCreate(left, top, starImage) {
    var star = stars.create(left, top, starImage);
    star.animations.add('spin');
    star.animations.play('spin', 8, true);
}

Now this alone will give you a good guess of whether or not they are overlapping, but if the stars are relatively small in width and height, you might not know.

It looks like you're working with Phaser JS framework and in your preload function you have this line:

game.load.spritesheet('star', 'star.png', 54, 52);

From the documentation in Phaser, you'll see that 54 relates to the width and 52 relates to the height of the image.

Documentation: https://phaser.io/examples/v2/loader/load-spritesheet

If you take the width of the star being 54px and add it to the 1stparameter you're passing into starCreate() and the height of 52px and pass it into the 2nd parameter into starCreate() you can get a pretty good idea of whether they're overlapping or not.

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

They may not appear to overlap visually, but you have to account for their full dimensions (54x52, disregard the fact that parts of them are transparent).

So if you compute the outlines of the two new ones, you can see they do overlap in a corner.