<!doctype html><html lang="en"><head><meta charset="UTF-8" /><title>canvas粒子形成下雪背景</title> body{ margin: 0px; padding: 0px; } #canvas{ display: block; background: #222; }</style></head><body> <canvas id="canvas"></canvas></body><script> var canvas = document.getElementById("canvas");//擷取canvas var ctx = canvas.getContext("2d");//建立畫筆 var w = canvas.width = window.innerWidth;//瀏覽器寬度 var h = canvas.height = window.innerHeight;//瀏覽器高度 window.onresize = function(){ w = canvas.width = window.innerWidth; h = canvas.height = window.innerHeight; };//當瀏覽器重新整理的時候重新整理 var num = 1000;//數量 var shuju = [];//空數組 for(i = 0;i<num;i++){ shuju.push({//數組末項添加 x : Math.random()*w, y : Math.random()*h, r : Math.random()*2 }); draw(shuju[i].x,shuju[i].y,shuju[i].r)//for迴圈迴圈darw function }; console.log(shuju[0]); function draw(x1,y1,r1){ ctx.beginPath();//開始繪畫 ctx.fillStyle = "#fff";//顏色 ctx.arc(x1,y1,r1,0,2*Math.PI,false)//arc園 ctx.fill();//填充 } function chageY(){ for(var i = 0;i<num;i++){//for迴圈 shuju[i].y += Math.random()*5; if(shuju[i].y > h){//大於高度 shuju[i].y = 0;//等於0 } draw(shuju[i].x,shuju[i].y,shuju[i].r);//調取 } } setInterval(function(){ ctx.clearRect(0,0,w,h);//清楚畫布 0 0 高度 寬度 chageY(); },10);</script>Start building with 50+ products and up to 12 months usage for Elastic Compute Service
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