Canvas波浪花环的示例代码

JS中的Canvas动画

几天没写博客了，今天又忙到很晚，教大家做一个波浪花环吧

效果图如上所示：

老规矩先把代码给大家，新建一个html文档(新建一个txt文本文档，把后缀名改为“ .html
”),以记事本打开，把复制好的代码粘贴进去，“ 保存 ”，退出，双击或右键选择浏览器打开。

祝大家前端学习愉快，在今后的日子中与君共勉

<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>Document</title><style>body {  background: #111;  padding:0;  margin:0;overflow:hidden;}</style></head><body><div id="wrapper"></div></body><script>(function(){use strict;let wrapper, canvas, ctx, width, height, Tau=Math.PI*2, PI180=Math.PI/180,systems=[];/* PlanetarySystem */let PlanetarySystem = function(id=pSys){Object.defineProperty(this, id,               { value:id, writable:true} );Object.defineProperty(this, x,                { value:0, writable:true });Object.defineProperty(this, y,                { value:0, writable:true });Object.defineProperty(this, allBodies,        { value:[], writable:true });Object.defineProperty(this, allBodiesLookup,  { value:{}, writable:true });    // fast id lookup for childrenObject.defineProperty(this, numBodies,        { value:0, writable:true });}PlanetarySystem.prototype.addBody = function(vo) {vo.parentSystem = this;vo.parentBody = vo.parentBody === null ? this : this.allBodiesLookup[vo.parentBody];let body = new PlanetaryBody(vo);body.update();this.allBodies.push(body);this.allBodiesLookup[vo.id] = body;this.numBodies += 1;}PlanetarySystem.prototype.setSpeedFactor = function(value){let body;for(let i=0; i<this.numBodies; i++){body = this.allBodies[i];body.setSpeedFactor(value);}}PlanetarySystem.prototype.update = function(){let body;for(let i=0; i<this.numBodies; i++){body = this.allBodies[i];body.update();}}/* PlanetaryBody */let PlanetaryBody = function(vo){Object.defineProperty(this, id,{ value:vo.id, writable:true} );Object.defineProperty(this, diameter,{ value:vo.diameter, writable:true });Object.defineProperty(this, colour,{ value:vo.colour, writable:true });Object.defineProperty(this, x,{ value:0, writable:true });Object.defineProperty(this, y,{ value:0, writable:true });Object.defineProperty(this, vx,{ value:0, writable:true });Object.defineProperty(this, vy,{ value:0, writable:true });Object.defineProperty(this, degrees,{ value:vo.degrees, writable:true });Object.defineProperty(this, speedBase,{ value:vo.speed, writable:true });Object.defineProperty(this, speed,{ value:vo.speed , writable:true });Object.defineProperty(this, orbitalRadius,{ value:vo.orbitalRadius, writable:true });Object.defineProperty(this, parentSystem,{ value:vo.parentSystem, writable:true });Object.defineProperty(this, parentBody,{ value:vo.parentBody, writable:true });return this;}PlanetaryBody.prototype.update = function(){let angle = this.degrees * PI180;this.degrees += this.speed;this.vx = this.orbitalRadius * Math.cos(angle);this.vy = this.orbitalRadius * Math.sin(angle);// update positionif(this.parentBody != null){this.x = this.vx + this.parentBody.x;this.y = this.vy + this.parentBody.y;}}/* init() */function init(){wrapper = document.querySelector(#wrapper);canvas = createCanvas(canvas, width, height);wrapper.appendChild(canvas);ctx = canvas.getContext(2d);setupEvents();resizeCanvas();/* Define new PlanetarySystem and set values */let system1 = new PlanetarySystem(pSys1);systems.push(system1);system1.x = width * .5;system1.y = height * .5;system1.addBody({id:sun, diameter:5, degrees:0, speed:0, colour:#FDFE1D, orbitalRadius:0, parentBody:null});for(let loop=30, i=0; i<loop; i+=1){system1.addBody({id:ball+i,diameter:5,degrees:0,speed:2 + (loop * 0.15) - (i* 0.2),colour:#FDFE1D,orbitalRadius:7*(i+1),parentBody:sun});}}/* Methods */function createCanvas(id, w, h){let tCanvas = document.createElement(canvas);tCanvas.width = w;tCanvas.height = h;tCanvas.id = id;return tCanvas;}function setupEvents(){window.onresize = resizeCanvas;}function resizeCanvas(){let rect = wrapper.getBoundingClientRect();width = window.innerWidth;height = window.innerHeight - rect.top -2;canvas.width = width;canvas.height = height;for(let i=0; i<systems.length; i++){systems[i].x = width * .5;systems[i].y = height * .5;}}function update(){for(let loop=systems.length, i=0; i<loop; i++){systems[i].update();}}function draw(){let system;let prev = null;for(let i=0; i<systems.length; i++){system = systems[i];let planetaryBody;for(let loop=system.numBodies, j=1; j<loop; j+=1) {planetaryBody = system.allBodies[j];ctx.beginPath();ctx.arc(planetaryBody.x, planetaryBody.y, planetaryBody.diameter, 0, Tau, false);ctx.fillStyle = planetaryBody.colour;ctx.fill();if(j>1){ctx.strokeStyle = planetaryBody.colour;ctx.lineWidth = 2;ctx.beginPath();ctx.moveTo(planetaryBody.x, planetaryBody.y);ctx.lineTo(prev.x, prev.y);ctx.stroke();}prev = {x:planetaryBody.x, y:planetaryBody.y};}}}function animate(){ctx.fillStyle = rgba(0,0,0, .05);ctx.fillRect(0, 0, width, height);update();draw();requestAnimationFrame(animate);}init();animate();}());</script></html>

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Canvas波浪花环的示例代码