<script>
var canvas = document.getElementById('canvas'),
ctx = canvas.getContext('2d'),
WIDTH = canvas.width = document.documentElement.clientWidth,
HEIGHT = canvas.height = document.documentElement.clientHeight,
para = {
num: 100,
color: false, // 颜色 如果是false 则是随机渐变颜色
radius: 0.9,
o: 0.09, // 判断圆消失的条件，数值越大，消失的越快
},
color,
circleColor,
round_arr = [];
window.onmousemove = function(event) {
X = event.clientX
Y = event.clientY
round_arr.push({
X: X,
Y: Y,
radius: para.radius,
o: 1
})
}
// 判断参数中是否设置color，设置则使用该color，否则为随机
if (para.color) {
circleColor = para.color
} else {
color = Math.random() * 360
}
function animate() {
if (!para.color) {
color += .1
circleColor = 'hsl(' + color + ',100%,80%)'
}
ctx.clearRect(0, 0, WIDTH, HEIGHT) // 清除屏幕
for (var i = 0; i < round_arr.length; i++) {
ctx.fillStyle = circleColor
ctx.beginPath() // 开始路径
ctx.arc(round_arr[i].X, round_arr[i].Y, round_arr[i].radius, 0, Math.PI * 2) // 画圆
ctx.closePath() // 结束路径
ctx.fill()
round_arr[i].radius += para.radius // 增大圆
round_arr[i].o -= para.o // 消失时间变快
if (round_arr[i].o <= 0) {
round_arr.splice(i, 1);
i--;
}
}
window.requestAnimationFrame(animate)
}
animate()
</script>
</body>
</html>
