Star Spinner

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Instructions: Spin the star with your mouse.

Konva Star Spinnerview raw
<!DOCTYPE html>
<html>
<head>
<script src="https://unpkg.com/[email protected]/konva.min.js"></script>
<meta charset="utf-8" />
<title>Konva Star Spinner Demo</title>
<style>
body {
margin: 0;
padding: 0;
overflow: hidden;
background-color: #f0f0f0;
}
</style>
</head>

<body>
<div id="container"></div>
<script>
var width = window.innerWidth;
var height = window.innerHeight;

Konva.angleDeg = false;
function animate(animatedLayer, star, frame) {
// 20% slow down per second
var angularFriction = 0.2;
var angularVelocityChange =
(star.angularVelocity * frame.timeDiff * (1 - angularFriction)) /
1000;
star.angularVelocity -= angularVelocityChange;

if (star.controlled) {
star.angularVelocity =
((star.rotation() - star.lastRotation) * 1000) / frame.timeDiff;
} else {
star.rotate((frame.timeDiff * star.angularVelocity) / 1000);
}

star.lastRotation = star.rotation();
}

var stage = new Konva.Stage({
container: 'container',
width: width,
height: height
});

var animatedLayer = new Konva.Layer();

var star = new Konva.Star({
x: stage.width() / 2,
y: stage.height() / 2,
outerRadius: 80,
innerRadius: 40,
stroke: '#005500',
fill: '#b5ff88',
strokeWidth: 4,
numPoints: 5,
lineJoin: 'round',
shadowOffsetX: 5,
shadowOffsetY: 5,
shadowBlur: 10,
shadowColor: 'black',
shadowOpacity: 0.5,
opacity: 0.8
});

// custom properties
star.lastRotation = 0;
star.angularVelocity = 6;
star.controlled = false;

star.on('mousedown touchstart', function(evt) {
this.angularVelocity = 0;
this.controlled = true;
});

animatedLayer.add(star);

var center = new Konva.Circle({
x: stage.width() / 2,
y: stage.height() / 2,
radius: 3,
fill: '#555'
});

animatedLayer.add(center);

// add listeners to container
stage.on('mouseup touchend', function() {
star.controlled = false;
});

stage.on('mousemove touchmove', function() {
if (star.controlled) {
var mousePos = stage.getPointerPosition();
var x = star.x() - mousePos.x;
var y = star.y() - mousePos.y;
star.rotation(0.5 * Math.PI + Math.atan(y / x));

if (mousePos.x <= stage.width() / 2) {
star.rotate(Math.PI);
}
}
});

stage.add(animatedLayer);

var anim = new Konva.Animation(function(frame) {
animate(animatedLayer, star, frame);
}, animatedLayer);

// wait one second and then spin the star
setTimeout(function() {
anim.start();
});
</script>
</body>
</html>
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