这篇文章主要介绍了原生JS+HTML5实现跟随鼠标一起流动的粒子动画效果,涉及javascript事件响应、数值运算及页面元素属性动态操作相关实现技巧,需要的朋友可以参考下

本文实例讲述了原生JS+HTML5实现跟随鼠标一起流动的粒子动画效果。分享给大家供大家参考,具体如下:

<!DOCTYPE html> <html lang="en"> <head> <meta charset=gbk> <title> 粒子效果演示</title> <meta name="description" content="HTML5/canvas demo, 500 particles to play around with." /> <meta name="keywords" content="html5,canvas,javascript,particles,interactive,velocity,programming,flash" /> <style type="text/css"> html, body { text-align: center; margin:0; padding:0; background: #000000; color: #666666; line-height: 1.25em; } #outer { position: absolute; top: 50%; left: 50%; width: 1px; height: 1px; overflow: visible; } #canvasContainer { position: absolute; width: 1000px; height: 560px; top: -280px; left: -500px; } canvas { border: 1px solid #333333; } a { color: #00CBCB; text-decoration:none; font-weight:bold; } a:hover { color:#FFFFFF; } #output { font-family: Arial, Helvetica, sans-serif; font-size: 0.75em; margin-top:4px; } #footer{ font-size: 0.6em; font-family: Arial, Helvetica, sans-serif; position: absolute; bottombottom:8px; width:98%; } </style> </head> <body> <p id="outer"> <p id="canvasContainer"> <canvas id="mainCanvas" width="1000" height="560"></canvas> <p id="output"></p> </p> </p> <script type="text/javascript"> //javascript部分 (function(){ var PI_2 = Math.PI * 2; var canvasW = 1000; var canvasH = 560; var numMovers = 600; var friction = 0.96; var movers = []; var canvas; var ctx; var canvasp; var outerp; var mouseX; var mouseY; var mouseVX; var mouseVY; var prevMouseX; var prevMouseY; var isMouseDown; function init(){ canvas = document.getElementById("mainCanvas"); if ( canvas.getContext ){ setup(); setInterval( run , 33 ); trace('你们好'); } else{ trace("Sorry, needs a recent version of Chrome, Firefox, Opera, Safari, or Internet Explorer 9."); } } function setup(){ outerp = document.getElementById("outer"); canvasp = document.getElementById("canvasContainer"); ctx = canvas.getContext("2d"); var i = numMovers; while ( i-- ){ var m = new Mover(); m.x = canvasW * 0.5; m.y = canvasH * 0.5; m.vX = Math.cos(i) * Math.random() * 34; m.vY = Math.sin(i) * Math.random() * 34; movers[i] = m; } mouseX = prevMouseX = canvasW * 0.5; mouseY = prevMouseY = canvasH * 0.5; document.onmousedown = onDocMouseDown; document.onmouseup = onDocMouseUp; document.onmousemove = onDocMouseMove; } function run(){ ctx.globalCompositeOperation = "source-over"; ctx.fillStyle = "rgba(8,8,12,0.65)"; ctx.fillRect( 0 , 0 , canvasW , canvasH ); ctx.globalCompositeOperation = "lighter"; mouseVX = mouseX - prevMouseX; mouseVY = mouseY - prevMouseY; prevMouseX = mouseX; prevMouseY = mouseY; var toDist = canvasW * 0.86; var stirDist = canvasW * 0.125; var blowDist = canvasW * 0.5; var Mrnd = Math.random; var Mabs = Math.abs; var i = numMovers; while ( i-- ){ var m = movers[i]; var x = m.x; var y = m.y; var vX = m.vX; var vY = m.vY; var dX = x - mouseX; var dY = y - mouseY; var d = Math.sqrt( dX * dX + dY * dY ) || 0.001; dX /= d; dY /= d; if ( isMouseDown ){ if ( d < blowDist ){ var blowAcc = ( 1 - ( d / blowDist ) ) * 14; vX += dX * blowAcc + 0.5 - Mrnd(); vY += dY * blowAcc + 0.5 - Mrnd(); } } if ( d < toDist ){ var toAcc = ( 1 - ( d / toDist ) ) * canvasW * 0.0014; vX -= dX * toAcc; vY -= dY * toAcc; } if ( d < stirDist ){ var mAcc = ( 1 - ( d / stirDist ) ) * canvasW * 0.00026; vX += mouseVX * mAcc; vY += mouseVY * mAcc; } vX *= friction; vY *= friction; var avgVX = Mabs( vX ); var avgVY = Mabs( vY ); var avgV = ( avgVX + avgVY ) * 0.5; if( avgVX < .1 ) vX *= Mrnd() * 3; if( avgVY < .1 ) vY *= Mrnd() * 3; var sc = avgV * 0.45; sc = Math.max( Math.min( sc , 3.5 ) , 0.4 ); var nextX = x + vX; var nextY = y + vY; if ( nextX > canvasW ){ nextX = canvasW; vX *= -1; } else if ( nextX < 0 ){ nextX = 0; vX *= -1; } if ( nextY > canvasH ){ nextY = canvasH; vY *= -1; } else if ( nextY < 0 ){ nextY = 0; vY *= -1; } m.vX = vX; m.vY = vY; m.x = nextX; m.y = nextY; ctx.fillStyle = m.color; ctx.beginPath(); ctx.arc( nextX , nextY , sc , 0 , PI_2 , true ); ctx.closePath(); ctx.fill(); } } function onDocMouseMove( e ){ var ev = e ? e : window.event; mouseX = ev.clientX - outerp.offsetLeft - canvasp.offsetLeft; mouseY = ev.clientY - outerp.offsetTop - canvasp.offsetTop; } function onDocMouseDown( e ){ isMouseDown = true; return false; } function onDocMouseUp( e ){ isMouseDown = false; return false; } function Mover(){ this.color = "rgb(" + Math.floor( Math.random()*255 ) + "," + Math.floor( Math.random()*255 ) + "," + Math.floor( Math.random()*255 ) + ")"; this.y = 0; this.x = 0; this.vX = 0; this.vY = 0; this.size = 1; } function rect( context , x , y , w , h ){ context.beginPath(); context.rect( x , y , w , h ); context.closePath(); context.fill(); } function trace( str ){ document.getElementById("output").innerHTML = str; } window.onload = init; })(); </script> </body> </html>

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