phaser/examples/physics/launcher follow world.js

// mods by Patrick OReilly
// twitter: @pato_reilly

var game = new Phaser.Game(800, 600, Phaser.CANVAS, 'phaser-example', { preload: preload, create: create, update: update, render: render });

function preload() {

    game.load.image('background','assets/misc/starfield.jpg');
    game.load.image('player','assets/sprites/phaser-dude.png');
    game.load.image('analog', 'assets/tests/fusia.png');
    game.load.image('arrow', 'assets/sprites/longarrow2.png');
}

var myTween;
var player;
var cursors;
var arrow;
var catchFlag = false;
var launchVelocity = 0;
var launched;

function create() {
    
    game.world.setBounds(0, 0, 5000, 600);
    game.add.tileSprite(0, 0, 5000, 600, 'background');
    
    var graphics = game.add.graphics(0,0);
    graphics.beginFill(0x049e0c);
    graphics.drawRect(395, 400, 10, 250);
    
    analog = game.add.sprite(400, 400, 'analog');
    analog.width = 8;
    analog.rotation = 220;
    analog.alpha = 0;
    analog.anchor.setTo(0.5, 0.0);
    
    arrow = game.add.sprite(400, 400, 'arrow');
    arrow.anchor.setTo(0.1, 0.5);
    arrow.alpha = 0;

    player = game.add.sprite(150, 320, 'player');
    player.anchor.setTo(0.5, 0.5);
    player.body.collideWorldBounds = true;
    player.body.bounce.setTo(0.9, 0.9);
    player.body.drag.setTo(100, 100);
    player.body.gravity.setTo(0, 8);

    // Enable input.
    player.inputEnabled = true;
    player.input.start(0, true);
    player.events.onInputDown.add(set);
    player.events.onInputUp.add(launch);
    //player.events.onInputOut.add(launch);
    
    // this tween is to make the camera return to left side of world when done launching
    // so it is not used until then
    myTween = game.add.tween(player).to({x: 150}, 5000, Phaser.Easing.Linear.None);
    myTween.onComplete.add(reappear, this);
    game.camera.follow(player, Phaser.Camera.FOLLOW_TOPDOWN);
}

function reappear() {
    
    launched = false;
    player.alpha = 1;
}

function set(player,pointer) {

    //disallow launching until reset
    if (!launched)
    {
        catchFlag = true;
        game.camera.follow(null);
        player.body.gravity.setTo(0,0);
        player.body.velocity.setTo(0,0);
    }
}

function launch() {
    
    if (catchFlag)
    {
        catchFlag = false;
        launched = true;
        game.camera.follow(player, Phaser.Camera.FOLLOW_TOPDOWN);
    
        arrow.alpha = 0;
        analog.alpha = 0;
        Xvector = (arrow.x - player.x)*3.8;
        Yvector = (arrow.y - player.y)*3.8; 
        player.body.gravity.setTo(0,8);
        player.body.velocity.setTo(Xvector,Yvector);
    }
}

function update() {

    arrow.rotation = game.physics.angleBetween(arrow, player);
    
    //  Track the player sprite to the mouse    
    if (catchFlag)
    {   
        distance = game.physics.distanceToPointer(arrow);
        theta = game.physics.angleToPointer(arrow);
        
        // Govern the distance the sprite is dragged away from launch post
        if (distance > 300)
        { 
            distance = 300;
            adjacentX = Math.cos(theta) * distance;
            oppositeY = Math.sin(theta) * distance;
            player.x = 400 + adjacentX;
            player.y = 400 + oppositeY;
            analog.height = distance;
        }
        else
        {
            player.x = game.input.activePointer.worldX;
            player.y = game.input.activePointer.worldY;
            analog.height = distance;
        }
        
        arrow.alpha = 1;
        analog.alpha = 0.5;
        analog.rotation = arrow.rotation - Math.PI/2;
        launchVelocity = analog.height;
    }
    
    //check sprite motion and if done, return camera to left side of world
    var tweening = myTween.isRunning;

    if (!tweening && launched && (player.x >= game.world.width-20 || player.body.deltaX() == 0))
    {
        player.body.velocity.setTo(0, 0);
        player.alpha = 0;
        myTween.start();
    }

}

function render() {

    game.debug.renderText("Drag the sprite and release to launch", 32, 32, 'rgb(0,255,0)');
    game.debug.renderCameraInfo(game.camera, 32, 64);
    game.debug.renderSpriteCoords(player, 32, 150);
    game.debug.renderText("Launch Velocity: " + parseInt(launchVelocity), 550, 32, 'rgb(0,255,0)');

}