canvas动画： 1.清空canvas 在绘制每一帧动画之前，需要清空所有。清空所有最简单的做法就是clearRect()方法 2.保存canvas状态 如果在绘制的过程中会更改canvas的状态(颜色、移动了坐标原点等),又在绘制每一帧时都是原始状态的话，则最好保存下canvas的状态 3.绘制动画图形 从这里开始一帧一帧的绘制动画 4.恢复canvas状态 如果你前面保存了canvas状态，则应该在绘制完成一帧之后恢复canvas状态 5.控制动画 我们可用通过canvas的方法或者自定义的方法把图像会知道到canvas上。正常情况，我们能看到绘制的结果是在脚本执行结束之后。 例如：我们不可能在一个 for 循环内部完成动画。为了执行动画，我们需要一些可以定时执行重绘的方法。
一般用到下面三个方法：
1.setInterval()
2.setTimeout()
3.requestAnimationFrame()
写个案例吧！哪里不详细请私发截图或评论在下方，方便第一时间补充。 悟空：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>canvas 悟空</title>
<style>
body{text-align:center;padding-top:3em;}
</style>
</head>
<body>
<canvas width="650" height="478"></canvas>
<script>
(function(){
var cvs=document.querySelector("canvas"),
g=cvs.getContext("2d");
g.lineWidth=2;
g.beginPath();
g.strokeStyle="#DE821B";
g.fillStyle="#FFDE00";
g.moveTo(261,337);
g.quadraticCurveTo(268,328,287,320);
g.lineTo(323,357);
g.quadraticCurveTo(281,415,243,377);
g.closePath();
g.fill();
g.stroke();
g.beginPath();
g.strokeStyle="#DE821B";
g.fillStyle="#FFDE00";
g.moveTo(86,265);
g.quadraticCurveTo(33,267,15,292);
g.lineTo(52,339);
g.quadraticCurveTo(88,328,101,341);
g.lineTo(92,336);
g.quadraticCurveTo(88,338,81,347);
g.bezierCurveTo(188,468,306,372,261,306);
g.closePath();
g.fill();
g.stroke();
g.beginPath();
g.fillStyle="#000000";
g.moveTo(251,330);
g.quadraticCurveTo(241,369,139,384);
g.quadraticCurveTo(231,400,273,343);
g.closePath();
g.fill();
g.strokeStyle="#842C00";
g.fillStyle="#BA6830";
g.beginPath();
g.moveTo(15,291);
g.bezierCurveTo(-16,339,31,348,51,339);
g.fill();
g.stroke();
g.beginPath();
g.moveTo(51,339);
g.quadraticCurveTo(65,295,15,291);
g.closePath();
g.fill();
g.beginPath();
g.moveTo(287,320);
g.bezierCurveTo(370,283,377,363,322,356);
g.fill();
g.stroke();
g.beginPath();
g.moveTo(287,320);
g.quadraticCurveTo(291,349,322,356);
g.closePath();
g.fill();
g.beginPath();
g.strokeStyle="#690203";
g.fillStyle="#000000";
g.moveTo(110,404);
g.quadraticCurveTo(57,440,113,453);
g.closePath();
g.fill();
g.stroke();
g.beginPath();
g.moveTo(110,424);
g.bezierCurveTo(58,465,117,498,173,463);
g.closePath();
g.fill();
g.stroke();
g.beginPath();
g.strokeStyle="#949591";
g.fillStyle="#D1D2D4";
g.moveTo(255,424);
g.quadraticCurveTo(242,436,222,437);
g.quadraticCurveTo(223,426,219,425);
g.quadraticCurveTo(231,417,255,424);
g.fill();
g.stroke()
g.closePath();
g.beginPath();
g.strokeStyle="#650300";
g.fillStyle="#ED1B24";
g.moveTo(211,404);
g.quadraticCurveTo(245,467,166,467);
g.closePath();
g.fill();
g.stroke();
g.beginPath();
g.moveTo(62,364);
g.quadraticCurveTo(45,427,127,433);
g.quadraticCurveTo(130,457,170,463);
g.quadraticCurveTo(203,442,194,403);
g.closePath();
g.fill();
g.stroke();
g.beginPath();
g.strokeStyle="#949591";
g.fillStyle="#FFFFFF";
g.moveTo(45,354);
g.quadraticCurveTo(174,413,246,410);
g.quadraticCurveTo(254,419,254,424);
g.quadraticCurveTo(226,414,204,438);
g.quadraticCurveTo(166,389,125,432);
g.quadraticCurveTo(102,400,66,403);
g.quadraticCurveTo(70,372,32,365);
g.quadraticCurveTo(36,360,45,354);
g.fill();
g.stroke();
g.closePath();
g.beginPath();
g.strokeStyle="#952C3D";
g.fillStyle="#EE707B";
g.moveTo(81,346);
g.quadraticCurveTo(142,418,224,398);
g.quadraticCurveTo(242,407,245,410);
g.quadraticCurveTo(221,410,206,424);
g.quadraticCurveTo(164,384,124,415);
g.quadraticCurveTo(114,396,79,394);
g.quadraticCurveTo(74,368,44,354);
g.quadraticCurveTo(64,343,83,346);
g.closePath();
g.fill();
g.stroke();
g.beginPath();
g.fillStyle="#000000";
g.moveTo(62,348);
g.bezierCurveTo(59,365,90,390,86,353);
g.lineTo(80,346);
g.quadraticCurveTo(69,345,62,348);
g.closePath();
g.fill();
g.beginPath();
g.moveTo(112,377);
g.quadraticCurveTo(114,380,132,388);
g.bezierCurveTo(114,397,88,386,112,377);
g.closePath();
g.fill();
g.beginPath();
g.moveTo(205,402);
g.quadraticCurveTo(212,401,226,398);
g.bezierCurveTo(245,406,196,420,205,403);
g.closePath();
g.fill();
g.beginPath();
g.strokeStyle="#952C3D";
g.fillStyle="#EE707B";
g.moveTo(106,395);
g.quadraticCurveTo(160,363,193,412);
g.quadraticCurveTo(160,389,125,414);
g.fill();
g.stroke();
g.closePath();
g.beginPath();
g.fillStyle="#000000";
g.moveTo(148,383);
g.quadraticCurveTo(164,384,177,396);
g.bezierCurveTo(153,405,140,382,148,383);
g.closePath();
g.fill();
g.beginPath();
g.moveTo(81,346);
g.quadraticCurveTo(48,345,31,365);
g.stroke();
g.closePath();
g.beginPath();
g.moveTo(228,399);
g.quadraticCurveTo(257,415,254,424);
g.stroke();
g.closePath();
g.beginPath();
g.strokeStyle="#DE821B";
g.fillStyle ="#DDA90C";
g.moveTo(40,137);
g.bezierCurveTo(-8,152,-12,225,34,222);
g.stroke();
g.closePath();
g.fill();
g.beginPath();
g.moveTo(38,137);
g.bezierCurveTo(0,152,4,194,32,202);
g.closePath();
g.fillStyle="#FFDE00";
g.fill();
g.beginPath();
g.moveTo(290,53);
g.quadraticCurveTo(250,17,135,51);
g.bezierCurveTo(-5,105,5,270,102,268);
g.stroke();
g.closePath();
g.fillStyle="#DDA90C";
g.fill();
g.beginPath();
g.fillStyle="#FFDE00";
g.moveTo(290,54);
g.bezierCurveTo(258,19,115,35,72,95);
g.bezierCurveTo(75,95,3,207,100,227);
g.closePath();
g.fill();
g.strokeStyle="#6B9C7F";
g.fillStyle="#B2DDC9";
g.beginPath();
g.moveTo(329,98);
g.bezierCurveTo(294,15,147,72,110,203);
g.fill();
g.stroke();
g.closePath();
g.beginPath();
g.fillStyle="#8DB2A4";
g.moveTo(247,62);
g.lineTo(261,72);
g.lineTo(280,70);
g.lineTo(262,58);
g.closePath();
g.fill();
g.beginPath();
g.strokeStyle="#007CB2";
g.fillStyle="#4DC6E1";
g.moveTo(88,268);
g.bezierCurveTo(132,277,173,358,214,318);
g.quadraticCurveTo(185,337,185,352);
g.bezierCurveTo(221,333,235,354,252,342);
g.quadraticCurveTo(272,340,270,358);
g.quadraticCurveTo(301,333,269,318);
g.lineTo(280,325);
g.quadraticCurveTo(292,297,165,227);
g.fill();
g.stroke();
g.closePath();
g.beginPath();
g.lineTo(265,312);
g.quadraticCurveTo(285,350,250,344);
g.quadraticCurveTo(262,333,253,318);
g.closePath();
g.fill();
g.stroke();
g.beginPath();
g.strokeStyle="#842C00";
g.fillStyle="#BA6830";
g.moveTo(351,141);
g.bezierCurveTo(313,-3,144,102,111,234);
g.bezierCurveTo(118,247,147,327,260,321);
g.stroke();
g.closePath();
g.fill();
g.beginPath();
g.fillStyle="#8B411F";
g.moveTo(316,83);
g.quadraticCurveTo(341,103,349,135);
g.quadraticCurveTo(338,120,337,119);
g.quadraticCurveTo(330,103,311,83);
g.fill();
g.closePath();
g.beginPath();
g.strokeStyle="#6B9C7F";
g.fillStyle="#B2DDC9";
g.moveTo(231,2);
g.quadraticCurveTo(245,75,311,78);
g.quadraticCurveTo(331,56,325,13);
g.quadraticCurveTo(316,16,303,5);
g.quadraticCurveTo(315,37,304,65);
g.quadraticCurveTo(263,58,264,2);
g.quadraticCurveTo(255,12,231,1);
g.quadraticCurveTo(235,61,301,78);
g.fill();
g.stroke();
g.closePath();
g.beginPath();
g.moveTo(287,57);
g.quadraticCurveTo(296,65,295,78);
g.quadraticCurveTo(315,85,315,80);
g.quadraticCurveTo(306,49,281,53);
g.stroke();
//g.closePath();
g.fill();
g.beginPath();
g.fillStyle="#8DB2A4";
g.moveTo(298,79);
g.quadraticCurveTo(322,88,311,70);
g.quadraticCurveTo(306,77,298,79);
g.fill();
g.closePath();
g.beginPath();
g.strokeStyle="#842C00";
g.fillStyle="#BA6830";
g.moveTo(127,207);
g.bezierCurveTo(62,164,36,281,135,268);
g.stroke();
g.closePath();
g.fill();
g.beginPath();
g.fillStyle="#95411D";
g.moveTo(123,236);
g.bezierCurveTo(92,203,64,250,122,236);
g.closePath();
g.fill();
g.beginPath();
g.moveTo(127,238);
g.lineWidth=1;
g.strokeStyle="#842C00";
g.quadraticCurveTo(104,220,88,225);
g.stroke();
g.beginPath();
g.moveTo(322,253);
g.strokeStyle="#842C00";
g.fillStyle="#FFFFFF";
g.lineWidth=2;
g.bezierCurveTo(276,235,376,197,348,135);
g.quadraticCurveTo(303,73,237,81);
g.quadraticCurveTo(203,93,170,129);
g.quadraticCurveTo(143,223,231,268);
g.bezierCurveTo(198,276,216,314,253,321);
g.quadraticCurveTo(279,319,314,302);
g.lineTo(317,294);
g.quadraticCurveTo(338,285,316,257);
g.closePath();
g.stroke();
g.fill();
g.beginPath();
g.fillStyle="#CCD0D5";
g.moveTo(341,127);
g.quadraticCurveTo(348,132,349,139);
g.quadraticCurveTo(361,172,331,206);
g.lineTo(329,201);
g.quadraticCurveTo(358,159,339,126);
g.fill();
g.closePath();
g.beginPath();
g.moveTo(279,137);
g.strokeStyle="#096F30";
g.fillStyle="#5CA74A";
g.quadraticCurveTo(295,114,308,132);
g.bezierCurveTo(312,142,307,143,312,162);
g.bezierCurveTo(296,139,303,129,280,136);
g.closePath();
g.stroke();
g.fill();
g.beginPath();
g.moveTo(279,137);
g.strokeStyle="#B21D21";
g.fillStyle="#ED1B24";
g.lineWidth=1;
g.moveTo(321,253);
g.bezierCurveTo(302,242,309,234,331,207);
g.bezierCurveTo(279,109,198,173,235,228);
g.bezierCurveTo(259,269,290,239,325,271);
g.quadraticCurveTo(324,265,316,258);
g.fill();
g.stroke();
g.closePath();
g.beginPath();
g.fillStyle="#B81214";
g.moveTo(328,202);
g.quadraticCurveTo(305,229,310,240);
g.quadraticCurveTo(311,229,332,207);
g.fill();
g.closePath();
g.beginPath();
g.moveTo(271,252);
g.strokeStyle="#FFDE00";
g.fillStyle="#FFFFFF";
g.bezierCurveTo(226,187,326,161,299,257);
g.stroke();
g.closePath();
g.stroke();
g.fill();
g.beginPath();
g.fillStyle="#49494B";
g.moveTo(292,255);
g.bezierCurveTo(280,217,315,200,299,257);
g.closePath();
g.fill();
g.beginPath();
g.fillStyle="#000000";
g.moveTo(299,251);
g.bezierCurveTo(272,242,314,187,299,251);
g.closePath();
g.fill();
g.beginPath();
g.fillStyle="#FFFFFF";
g.moveTo(298,229);
g.bezierCurveTo(292,208,287,255,298,233);
g.closePath();
g.fill();
g.beginPath();
g.strokeStyle="#6DAE5E";
g.moveTo(310,267);
g.bezierCurveTo(328,282,312,308,293,303);
g.stroke();
g.strokeStyle="#842C00";
g.moveTo(321,292);
g.bezierCurveTo(322,301,318,304,312,298);
g.stroke();
g.fill();
g.closePath();
g.beginPath();
g.fillStyle="#97441E";
g.moveTo(8,331);
g.quadraticCurveTo(28,336,53,318);
g.quadraticCurveTo(53,328,50,339);
g.quadraticCurveTo(18,347,10,331);
g.fill();
g.closePath();
g.beginPath();
g.moveTo(311,352);
g.quadraticCurveTo(326,346,338,354);
g.quadraticCurveTo(327,359,311,352);
g.fill();
g.closePath();
g.beginPath();
g.fillStyle="#DDA80C";
g.moveTo(54,318);
g.bezierCurveTo(77,303,137,338,107,347);
g.quadraticCurveTo(94,324,51,339);
g.quadraticCurveTo(54,326,54,318);
g.fill();
g.closePath();
g.beginPath();
g.moveTo(107,347);
g.quadraticCurveTo(104,350,88,353);
g.lineTo(83,345);
g.quadraticCurveTo(85,341,91,337);
g.quadraticCurveTo(99,341,107,345);
g.fill();
g.closePath();
g.beginPath();
g.moveTo(260,371);
g.quadraticCurveTo(277,387,311,352);
g.quadraticCurveTo(316,356,322,356);
g.quadraticCurveTo(287,408,250,382);
g.fill();
g.closePath();
g.strokeStyle="#43AEDA";
g.beginPath();
g.moveTo(337,297);
g.quadraticCurveTo(396,311,460,301);
g.bezierCurveTo(442,296,453,278,462,283);
g.moveTo(475,274);
g.bezierCurveTo(487,299,447,284,464,265);
g.bezierCurveTo(476,251,487,262,489,263);
g.bezierCurveTo(464,227,533,216,533,243);
g.bezierCurveTo(530,277,488,246,514,241);
g.moveTo(529,228);
g.bezierCurveTo(554,165,660,205,622,249);
g.bezierCurveTo(667,267,620,326,585,278);
g.bezierCurveTo(578,298,533,273,559,254);
g.bezierCurveTo(587,244,581,282,565,270);
g.moveTo(637,287);
g.bezierCurveTo(672,316,624,331,614,323);
g.moveTo(598,317);
g.bezierCurveTo(595,337,566,309,592,306);
g.bezierCurveTo(626,304,616,346,585,334);
g.bezierCurveTo(570,353,536,346,530,324);
g.bezierCurveTo(529,283,589,323,544,320);
g.moveTo(516,317);
g.bezierCurveTo(494,307,527,293,532,310);
g.moveTo(528,327);
g.bezierCurveTo(517,337,488,332,477,314);
g.moveTo(480,311);
g.quadraticCurveTo(425,319,337,297);
g.stroke();
g.closePath();
g.beginPath();
g.fillStyle="#C7E6F4";
g.moveTo(480,311);
g.quadraticCurveTo(425,319,337,297);
g.quadraticCurveTo(425,315,473,306);
g.fill();
g.closePath();
g.beginPath();
g.moveTo(606,202);
g.quadraticCurveTo(642,216,623,250);
g.quadraticCurveTo(615,244,601,248);
g.quadraticCurveTo(632,228,606,202);
g.fill();
g.closePath();
g.beginPath();
g.moveTo(630,254);
g.bezierCurveTo(663,282,609,315,589,281);
g.bezierCurveTo(589,292,650,299,630,254);
g.fill();
g.closePath();
g.beginPath();
g.moveTo(646,296);
g.quadraticCurveTo(659,325,614,324);
g.lineTo(614,324);
g.quadraticCurveTo(648,319,646,296);
g.fill();
g.closePath();
g.beginPath();
g.moveTo(573,328);
g.quadraticCurveTo(574,339,561,345);
g.quadraticCurveTo(578,343,585,334);
g.fill();
g.closePath();
g.beginPath();
g.moveTo(501,331);
g.quadraticCurveTo(539,325,523,302);
g.quadraticCurveTo(535,309,530,313);
g.quadraticCurveTo(529,309,528,326);
g.quadraticCurveTo(515,335,501,331);
g.fill();
g.closePath();
})();
</script>
</body>
</html>圆形钟表：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>圆形钟表</title>
<style>
body {
padding: 0;
margin: 0;
background-color: rgba(0, 0, 0, 0.1)
}
canvas {
display: block;
margin: 200px auto;
}
</style>
</head>
<body>
<canvas id="solar" width="300" height="300"></canvas>
<script>
init();
function init(){
let canvas = document.querySelector("#solar");
let ctx = canvas.getContext("2d");
draw(ctx);
}
function draw(ctx){
requestAnimationFrame(function step(){
drawDial(ctx); //绘制表盘
drawAllHands(ctx); //绘制时分秒针
requestAnimationFrame(step);
});
}
/*绘制时分秒针*/
function drawAllHands(ctx){
let time = new Date();
let s = time.getSeconds();
let m = time.getMinutes();
let h = time.getHours();
let pi = Math.PI;
let secondAngle = pi / 180 * 6 * s; //计算出来s针的弧度
let minuteAngle = pi / 180 * 6 * m secondAngle / 60; //计算出来分针的弧度
let hourAngle = pi / 180 * 30 * h minuteAngle / 12; //计算出来时针的弧度
drawHand(hourAngle, 60, 6, "red", ctx); //绘制时针
drawHand(minuteAngle, 106, 4, "green", ctx); //绘制分针
drawHand(secondAngle, 129, 2, "blue", ctx); //绘制秒针
}
/*绘制时针、或分针、或秒针
* 参数1：要绘制的针的角度
* 参数2：要绘制的针的长度
* 参数3：要绘制的针的宽度
* 参数4：要绘制的针的颜色
* 参数4：ctx
* */
function drawHand(angle, len, width, color, ctx){
ctx.save();
ctx.translate(150, 150); //把坐标轴的远点平移到原来的中心
ctx.rotate(-Math.PI / 2 angle); //旋转坐标轴。 x轴就是针的角度
ctx.beginPath();
ctx.moveTo(-4, 0);
ctx.lineTo(len, 0); // 沿着x轴绘制针
ctx.lineWidth = width;
ctx.strokeStyle = color;
ctx.lineCap = "round";
ctx.stroke();
ctx.closePath();
ctx.restore();
}
/*绘制表盘*/
function drawDial(ctx){
let pi = Math.PI;
ctx.clearRect(0, 0, 300, 300); //清除所有内容
ctx.save();
ctx.translate(150, 150); //一定坐标原点到原来的中心
ctx.beginPath();
ctx.arc(0, 0, 148, 0, 2 * pi); //绘制圆周
ctx.stroke();
ctx.closePath();
for (let i = 0; i < 60; i ){//绘制刻度。
ctx.save();
ctx.rotate(-pi / 2 i * pi / 30); //旋转坐标轴。坐标轴x的正方形从 向上开始算起
ctx.beginPath();
ctx.moveTo(110, 0);
ctx.lineTo(140, 0);
ctx.lineWidth = i % 5 ? 2 : 4;
ctx.strokeStyle = i % 5 ? "blue" : "red";
ctx.stroke();
ctx.closePath();
ctx.restore();
}
ctx.restore();
}
</script>
</body>
</html>矩阵箭头：
<!DOCTYPE html>
<html lang="en" >
<head>
<meta charset="UTF-8">
<title>矩阵箭头</title>
<style>
* {
box-sizing: border-box;
margin: 0;
padding: 0;
}
.container {
height: 100%;
overflow: hidden;
position: absolute;
width: 100%;
}
</style>
</head>
<body>
<div class="container">
<canvas></canvas>
</div>
</body>
<script>
const canvas = document.querySelector("canvas");
let ctx = canvas.getContext("2d");
var mouse = {
x: innerWidth / 2,
y: innerHeight / 2 };
class Arrow {
constructor(x, y, radius) {
this.x = x;
this.y = y;
this.radius = radius;
}
draw() {
const center = {
x: this.x,
y: this.y };
const xDist = this.x - mouse.x;
const yDist = this.y - mouse.y;
const distance = Math.sqrt(Math.pow(xDist, 2) Math.pow(yDist, 2));
let radius = this.radius / 3 this.radius * distance / 600;
if (radius < this.radius) {
radius = this.radius;
}
let angle, x, y;
ctx.beginPath();
angle = Math.atan2(yDist, xDist) - 90;
x = radius * Math.cos(angle) center.x;
y = radius * Math.sin(angle) center.y;
ctx.moveTo(x, y);
nextPoint();
ctx.lineTo(x, y);
nextPoint();
ctx.lineWidth = 1 distance / 600 * 4;
ctx.stroke();
function nextPoint() {
angle = 1 / 3 * (2 * Math.PI);
x = radius * Math.cos(angle) center.x;
y = radius * Math.sin(angle) center.y;
ctx.lineTo(x, y);
}
}
update() {
this.draw();
}}
let arrows;
function init() {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
arrows = [];
for (var x = 0; x <= canvas.width 40; x = 40) {
for (var y = 0; y <= canvas.height 40; y = 40) {
arrows.push(new Arrow(x, y, -20));
}
}
}
// Animation Loop
function animate() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
arrows.forEach(Arrow => {
Arrow.update();
});
requestAnimationFrame(animate);
}
init();
animate();
// Event Listeners
addEventListener("mousemove", function (event) {
mouse.x = event.clientX;
mouse.y = event.clientY;
});
addEventListener("resize", function () {
canvas.width = innerWidth;
canvas.height = innerHeight;
init();
});
document.addEventListener("touchstart", function (e) {
e.preventDefault();
mouse.x = e.targetTouches[0].clientX;
mouse.y = e.targetTouches[0].clientY;
});
document.addEventListener("touchmove", function (e) {
e.preventDefault();
mouse.x = e.targetTouches[0].clientX;
mouse.y = e.targetTouches[0].clientY;
});
</script>
</html>磁力虫：
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>磁力虫</title>
<style>
html,body {
height: 100%;
overflow: hidden;
}
body {
background: radial-gradient(#222, #000);
}
canvas {
display: block;
}
</style>
</head>
<body>
<canvas id="canvas"></canvas>
<script>
var a = document.getElementById( 'canvas' ),
c = a.getContext( '2d' );
var chains = [],
chainCount = 30,
entityCount = 10,
w = a.width,
h = a.height,
cx = w / 2,
cy = h / 2,
mx = cx,
my = cy,
md = 0,
tick = 0,
maxa = 2,
maxv = 1,
avoidTick = 20,
avoidThresh = 50,
TWO_PI = Math.PI * 2;
function rand( min, max ) {
return Math.random() * ( max - min ) min;
}
function Impulse() {
this.x = cx;
this.y = cy;
this.ax = 0;
this.ay = 0;
this.vx = 0;
this.vy = 0;
this.r = 1;
}
Impulse.prototype.step = function() {
this.x = this.vx;
this.y = this.vy;
if( this.x this.r >= w || this.x <= this.r ) { this.vx = 0; this.ax = 0; }
if( this.y this.r >= h || this.y <= this.r ) { this.vy = 0; this.ay = 0; }
if( this.x this.r >= w ) { this.x = w - this.r; }
if( this.x <= this.r ) { this.x = this.r; }
if( this.y this.r >= h ) { this.y = h - this.r; }
if( this.y <= this.r ) { this.y = this.r; }
if( md ) {
this.vx = ( mx - this.x ) * 0.03;
this.vy = ( my - this.y ) * 0.03;
}
this.ax = rand( -0.4, 0.4 );
this.ay = rand( -0.4, 0.4 );
this.vx = this.ax;
this.vy = this.ay;
this.ax *= Math.abs( this.ax ) > maxa ? 0.75 : 1;
this.ay *= Math.abs( this.ay ) > maxa ? 0.75 : 1;
this.vx *= Math.abs( this.vx ) > maxv ? 0.75 : 1;
this.vy *= Math.abs( this.vy ) > maxv ? 0.75 : 1;
};
function Chain() {
this.branches = [];
this.impulse = new Impulse();
this.branches.push( new Branch({
chain: this,
attractor: this.impulse
}));
}
Chain.prototype.step = function() {
this.impulse.step();
this.branches.forEach( function( branch, i ) {
branch.step();
});
this.branches.forEach( function( branch, i ) {
branch.draw();
});
};
function Branch( opt ) {
this.entities = [];
this.chain = opt.chain;
this.avoiding = 0;
var entity;
for( var i = 0; i < entityCount; i ) {
entity = new Entity({
branch: this,
i: i,
x: cx,
y: cy,
radius: 1 ( entityCount - i ) / entityCount * 5,
damp: 0.2,
attractor: i === 0 ? opt.attractor : this.entities[ i - 1 ]
});
this.entities.push( entity );
}
}
Branch.prototype.step = function() {
var i = chains.length;
while( i-- ) {
var impulse = this.chain.impulse,
oImpulse = chains[ i ].impulse,
dx = oImpulse.x - impulse.x,
dy = oImpulse.y - impulse.y,
dist = Math.sqrt( dx * dx dy * dy );
if( !md && impulse !== oImpulse && dist < avoidThresh ) {
impulse.ax = 0;
impulse.ay = 0;
impulse.vx -= dx * 0.1;
impulse.vy -= dy * 0.1;
this.avoiding = avoidTick;
}
}
this.entities.forEach( function( entity, i ) {
entity.step();
});
if( this.avoiding > 0 ) {
this.avoiding--;
}
};
Branch.prototype.draw = function() {
var self = this;
c.beginPath();
c.moveTo( this.entities[ 0 ].x, this.entities[ 0 ].y );
this.entities.forEach( function( entity, i ) {
if( i > 0 ) {
c.lineTo( entity.x, entity.y );
}
});
c.strokeStyle = 'hsla(' ( md ? 120 : ( self.avoiding ? 0 : 200 ) ) ', 70%, 60%, 0.3)';
c.stroke();
this.entities.forEach( function( entity, i ) {
c.save();
c.translate( entity.x, entity.y );
c.beginPath();
c.rotate( entity.rot );
if( entity.i === 0 ) {
c.fillStyle = ( md ? '#6c6' : ( self.avoiding ? '#c66' : '#6bf' ) );
} else {
c.fillStyle = 'hsla(' ( md ? 120 : ( self.avoiding ? 0 : 200 ) ) ', 70%, ' Math.min( 50, ( 5 ( ( entity.av / maxv ) * 20 ) ) ) '%, ' ( ( ( entityCount - i ) / entityCount ) ) ')';
}
c.fillRect( -entity.radius, -entity.radius, entity.radius * 2, entity.radius * 2 );
c.restore();
});
};
function Entity( opt ) {
this.branch = opt.branch;
this.i = opt.i;
this.x = opt.x;
this.y = opt.y;
this.vx = 0;
this.vy = 0;
this.radius = opt.radius;
this.attractor = opt.attractor;
this.damp = opt.damp;
}
Entity.prototype.step = function() {
this.vx = ( this.attractor.x - this.x ) * this.damp;
this.vy = ( this.attractor.y - this.y ) * this.damp;
this.x = this.vx;
this.y = this.vy;
this.av = ( Math.abs( this.vx ) Math.abs( this.vy ) ) / 2;
var dx = this.attractor.x - this.x,
dy = this.attractor.y - this.y;
this.rot = Math.atan2( dy, dx );
};
function loop() {
requestAnimationFrame( loop );
c.globalCompositeOperation = 'destination-out';
c.fillStyle = 'rgba(0, 0, 0, 1)';
c.fillRect( 0, 0, a.width, a.height );
c.globalCompositeOperation = 'lighter';
chains.forEach( function( chain, i ) {
chain.step();
});
tick ;
}
function resize() {
a.width = window.innerWidth;
a.height = window.innerHeight;
w = a.width;
h = a.height;
cx = w / 2;
cy = h / 2;
}
window.addEventListener( 'resize', resize );
window.addEventListener( 'mousedown', function() {
md = 1;
});
window.addEventListener( 'mouseup', function() {
md = 0;
});
window.addEventListener( 'mousemove', function( e ) {
mx = e.clientX;
my = e.clientY;
});
resize();
for( var i = 0; i < chainCount; i ) {
chains.push( new Chain() );
}
loop();
reset();
</script>
</body>
</html>
前端的学习不是一蹴而就，不积跬步无以至千里，不积小流无以成江海。持续不断的努力才能让你我有所收获，专业的知识还得到机构去学习，培训机构的设立有其存在的必然性，你钱花对了吗？
