


Share the practical 3D development of konva based on canvas in js, taking the rotating five-pointed star as an example
Jul 23, 2018 pm 05:46 PMThis article is a development of konva based on canvas. It mainly uses the Tween object in konva. Tween is the core object that controls the animation of Konva objects. The animation in this case is a type of tween animation: rotation animation. A starting angle of 0 and an ending angle of 360 degrees are given. An animation time of 6 seconds is also given. At the same time, in order to achieve a loop effect, after each animation is executed, the animation is reset (that is, returned to 0 degrees) and the animation is executed again.
1. Effect
2. Idea
Mainly use the Tween object in konva . tween, the English meaning is between the two, is actually Tweened Aniamation (the animation between the two, that is, the tween animation). What is tween animation? To put it bluntly, it gives you an initial state and allows you to gradually change to another state. For example, specify the initial (0, 0) coordinates and the end point coordinates (100, 100), and move from the starting point to the end point. How to move? Let the computer calculate it by itself. The movement process will produce displacement animation, which is a kind of tween animation.
#Tween is the core object that controls the animation of Konva objects.
Tween can control all numerical type attributes for animation, such as: x, y , rotation, width, height, radius, strokeWidth, opacity, scaleX, etc.
<!DOCTYPE html>
<html lang="zh-cmn-Hans">
<head>
<meta charset="UTF-8">
<title>使用js canvas庫konva創(chuàng)建補間動畫 楚士巖 2018年7月19日</title>
</head>
<body>
<p id="container"></p>
<script type="text/javascript" src="js/konva/konva2.1.7/konva.js"></script>
<script type="text/javascript">
var stage = new Konva.Stage({
container: "container",
width: window.innerWidth,
height: window.innerHeight
});
var layer = new Konva.Layer();
var star = new Konva.Star({
x: stage.getWidth() / 2,
y: stage.getHeight() / 2,
numPoints: 5, // 設置為五角形
innerRadius: 40, // innerRadius和outerRadius都必須設置
outerRadius: 100,
fill: 'red',
});
layer.add(star);
var tween = new Konva.Tween({
node: star, // 需要添加補間動畫的組件
duration: 6, // 持續(xù)時間
draggable: true, // 設置可以拖拽
easing: Konva.Easings.Linear, // 線性速度,即勻速
rotation: 360, // 6秒內旋轉360度
onFinish: function () { // 動畫完成時的回調函數(shù)
this.reset();// 重置動畫
this.play(); // 重新播放動畫
}
/* 不能使用yoyo:true代替onFinish中的代碼
因為使用yoyo,執(zhí)行一圈后(6秒360度),會旋轉回到原始狀態(tài),
然后再執(zhí)行下一圈動畫。這樣就無法實現(xiàn)五角星循環(huán)不停的朝一個方向旋轉
*/
});
tween.play();
stage.add(layer);
</script>
</body>
</html>
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canvas and JS to implement dynamic clock animation
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