Talking about TwinSpin game, Game development, HTML5, Javascript and Phaser.
TwinSpin was a fun Flash game I am not even able to find anymore. If you know a working link, please tell me. All I was able to find at the moment is an iOS version.
Basically you have two spinning orbs. Each orb spins around the other orb, one clockwise and one counter-clockwise. Tapping or clicking the screen, the spinning orb stops and the other orb starts spinning.
Have a look:
Click or tap to stop one orb and move another.
It would have been very easy to handle everything with a single sprite with an anchor point in the centre of the fixed orb making it rotate clockwise or counter clockwise but there’s a detail: orbs move along a circular path but do not rotate themselves.
We can solve it with three sprites: one for each orb and one for the arm. We’ll move orbs using trigonometry, and here is the very basic source code:
var game;
var ballDistance = 160;
var rotationSpeed = 4;
window.onload = function() {
game = new Phaser.Game(640, 960, Phaser.AUTO, "");
game.state.add("PlayGame", playGame);
game.state.start("PlayGame");
}
var playGame = function(game){};
playGame.prototype = {
preload: function(){
game.load.image("firstball", "firstball.png");
game.load.image("secondball", "secondball.png");
game.load.image("arm", "arm.png");
game.scale.pageAlignHorizontally = true;
game.scale.pageAlignVertically = true;
game.scale.scaleMode = Phaser.ScaleManager.SHOW_ALL;
},
create: function(){
this.arm = game.add.sprite(game.width / 2, game.height / 2, "arm");
this.arm.anchor.set(0, 0.5);
this.balls = [
game.add.sprite(game.width / 2, game.height / 2, "firstball"),
game.add.sprite(game.width / 2, game.height / 2, "secondball")
]
this.balls[0].anchor.set(0.5);
this.balls[1].anchor.set(0.5);
this.rotationAngle = 0;
this.rotatingBall = 1;
game.input.onDown.add(this.changeBall, this);
},
update: function(){
this.rotationAngle = (this.rotationAngle + rotationSpeed * (this.rotatingBall * 2 - 1)) % 360;
this.arm.angle = this.rotationAngle + 90;
this.balls[this.rotatingBall].x = this.balls[1 - this.rotatingBall].x - ballDistance * Math.sin(Phaser.Math.degToRad(this.rotationAngle));
this.balls[this.rotatingBall].y = this.balls[1 - this.rotatingBall].y + ballDistance * Math.cos(Phaser.Math.degToRad(this.rotationAngle));
},
changeBall:function(){
this.arm.position = this.balls[this.rotatingBall].position
this.rotatingBall = 1 - this.rotatingBall;
this.rotationAngle = this.balls[1 - this.rotatingBall].position.angle(this.balls[this.rotatingBall].position, true) - 90;
}
}
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