<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>添加天空渐变</title> </head> <body> <canvas id="canvas" style="margin:0 auto;"> The current browser does not support Canvas, can replace the browser a try! </canvas> <script> window.onload = function(){ var canvas = document.getElementById('canvas'); canvas.width = 1200; canvas.height = 800; if(canvas.getContext('2d')){ var context = canvas.getContext('2d'); // context.fillStyle = "#000"; var skyStyle = context.createLinearGradient(0,0,0,canvas.height); skyStyle.addColorStop(0.0,'black'); skyStyle.addColorStop(1.0,'#035'); context.fillStyle = skyStyle; context.fillRect(0,0,canvas.width,canvas.height) for(var i=0;i<200;i++){ var r = Math.random() * 5 + 5; var x = Math.random() * canvas.width; var y = Math.random() * canvas.height * 0.65; var a = Math.random() * 360; drawStar(context , x , y , r , a ) } }else{ alert('当前游览器不支持Canvas，请更换游览器后再试！'); } } function drawStar(cxt,x,y,R,rot){ cxt.save(); cxt.translate(x,y); cxt.rotate(rot/180*Math.PI); cxt.scale(0.05*R,0.05*R) starPath(cxt); cxt.fillStyle = "#fb3"; cxt.strokeStyle = "#fd5"; cxt.lineWidth = 3; cxt.lineJoin = "round"; cxt.fill(); cxt.stroke(); cxt.restore() } function starPath(cxt){ cxt.beginPath(); for(var i=0;i<5;i++){ cxt.lineTo(Math.cos( (18+i*72) / 180 * Math.PI )*20, -Math.sin( (18+i*72) / 180 * Math.PI )*20); cxt.lineTo(Math.cos( (54+i*72) / 180 * Math.PI )*0.5*20, -Math.sin( (54+i*72) / 180 * Math.PI )*0.5*20); } cxt.closePath(); } </script> </body> <script> /*图形变换 位移 translate(x,y) 旋转 rotate(deg) 缩放 scale(sx,sy) */ </script> </html>