帆布小球碰壁效果-白红宇

帆布小球碰壁效果

阅读量：7091 次

发布时间：2019-06-28

本文共 1220 字，大约阅读时间需要 4 分钟。

<!doctype html>

<html>

<head>

<title>帆布小球碰壁效果</title>

<style>

canvas {

border:2px dotted #ccc;
}
</style>
</head>
<body>
<canvas id="canvas" width="300" height="450"></canvas>
<script type="text/javascript">
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var raf;
var ball = {

x: 100,
y: 100,
vx: 5,
vy: 2,
radius: 25,
color: 'blue',
draw: function() {

ctx.beginPath();
ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2, true);
ctx.closePath();
ctx.fillStyle = this.color;
ctx.fill();
}
};
function draw() {

ctx.clearRect(0, 0, canvas.width, canvas.height);
ball.draw();
ball.x += ball.vx;
ball.y += ball.vy;
if (ball.y + ball.vy > canvas.height ||
ball.y + ball.vy < 0) {

ball.vy = -ball.vy;
}
if (ball.x + ball.vx > canvas.width ||
ball.x + ball.vx < 0) {

ball.vx = -ball.vx;
}
raf = window.requestAnimationFrame(draw);
}
canvas.addEventListener('mouseover', function(e) {

raf = window.requestAnimationFrame(draw);
});
canvas.addEventListener("mouseout", function(e) {

window.cancelAnimationFrame(raf);
});
ball.draw();
</script>
</body>
</html>

转载于:https://www.cnblogs.com/web-chuanfa/p/9131377.html

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