实例介绍
【实例简介】一款利用HTML5 Canvas模拟出来的粒子特效(部分电脑会有点卡,属于正常因为代码中的循环导致)
【实例截图】
【核心代码】
【实例截图】
【核心代码】
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>htm5浪漫表白</title> </head> <body> <script type="text/javascript"> BLUR = false; PULSATION = true; PULSATION_PERIOD = 600; PARTICLE_RADIUS = 4; /* disable blur before using blink */ BLINK = false; GLOBAL_PULSATION = false; QUALITY = 2; /* 0 - 5 */ /* set false if you prefer rectangles */ ARC = true; /* trembling blur = fun */ TREMBLING = 0; /* 0 - infinity */ FANCY_FONT = "Arial"; BACKGROUND = "#000"; BLENDING = true; /* if empty the text will be a random number */ var TEXT; num = 0; TEXTArray = ["HELLO WORLD!"]; QUALITY_TO_FONT_SIZE = [10, 12, 20, 50, 100, 350]; QUALITY_TO_SCALE = [20, 6, 4, 2, 0.9, 0.5]; QUALITY_TO_TEXT_POS = [10, 20, 60, 100, 370, 280]; window.onload = function () { document.body.style.backgroundColor = BACKGROUND; var canvas = document.getElementById("canvas"); var ctx = canvas.getContext("2d"); var W = canvas.width; var H = canvas.height; var tcanvas = document.createElement("canvas"); var tctx = tcanvas.getContext("2d"); tcanvas.width = W; tcanvas.height = H; total_area = W * H; total_particles = 1500; single_particle_area = total_area / total_particles; area_length = Math.sqrt(single_particle_area); var particles = []; function createParticles(num){ single_particle_area = total_area / num; for (var i = 1; i <= num; i ) { particles.push(new particle(i)); } } function particle(i) { this.r = Math.round(Math.random() * 255 | 0); this.g = Math.round(Math.random() * 255 | 0); this.b = Math.round(Math.random() * 255 | 0); this.alpha = 1; this.x = (i * area_length) % W; this.y = (i * area_length) / W * area_length; /* randomize delta to make particles sparkling */ this.deltaOffset = Math.random() * PULSATION_PERIOD | 0; this.radius = 0.7; } var positions = []; function new_positions() { TEXT = TEXTArray[num]; if (num < TEXTArray.length - 1) { num ; } else { num = 0; } //alert(TEXT); tctx.fillStyle = "white"; tctx.fillRect(0, 0, W, H) //tctx.fill(); tctx.font = "bold " QUALITY_TO_FONT_SIZE[QUALITY] "px " FANCY_FONT; //tctx.textAlign='center';//文本水平对齐方式 //tctx.textBaseline='middle'; //tctx.strokeStyle = "black"; tctx.fillStyle = "#f00"; tctx.strokeText(TEXT,10, 80); // tctx.fillText(TEXT, 20, 60); image_data = tctx.getImageData(0, 0, W, H); pixels = image_data.data; positions = []; countPixels = 0; for (var i = 0; i < pixels.length; i = i 2) { if (pixels[i] != 255) { position = { x: (i / 2 % W | 0) * QUALITY_TO_SCALE[QUALITY] | 0, y: (i / 2 / W | 0) * QUALITY_TO_SCALE[QUALITY] | 0 } countPixels ; positions.push(position); } } createParticles(countPixels); get_destinations(); } function draw() { var now = Date.now(); ctx.globalCompositeOperation = "source-over"; if (BLUR) ctx.globalAlpha = 0.1; else if (!BLUR && !BLINK) ctx.globalAlpha = 1.0; ctx.fillStyle = BACKGROUND; ctx.fillRect(0, 0, W, H) if (BLENDING) ctx.globalCompositeOperation = "lighter"; for (var i = 0; i < particles.length; i ) { p = particles[i]; /* in lower qualities there is not enough full pixels for all of them - dirty hack*/ if (isNaN(p.x)) continue ctx.beginPath(); ctx.fillStyle = "rgb(" p.r ", " p.g ", " p.b ")"; ctx.fillStyle = "rgba(" p.r ", " p.g ", " p.b ", " p.alpha ")"; if (BLINK) ctx.globalAlpha = Math.sin(Math.PI * mod * 1.0); if (PULSATION) { /* this would be 0 -> 1 */ var mod = ((GLOBAL_PULSATION ? 0 : p.deltaOffset) now) % PULSATION_PERIOD / PULSATION_PERIOD; /* lets make the value bouncing with sinus */ mod = Math.sin(mod * Math.PI); } else var mod = 1; var offset = TREMBLING ? TREMBLING * (-1 Math.random() * 2) : 0; var radius = PARTICLE_RADIUS * p.radius; if (!ARC) { ctx.fillRect(offset p.x - mod * radius / 2 | 0, offset p.y - mod * radius / 2 | 0, radius * mod, radius * mod); } else { ctx.arc(offset p.x | 0, offset p.y | 0, radius * mod, Math.PI * 2, false); ctx.fill(); } p.x = (p.dx - p.x) / 10; p.y = (p.dy - p.y) / 10; } } function get_destinations() { for (var i = 0; i < particles.length; i ) { pa = particles[i]; particles[i].alpha = 1; var distance = []; nearest_position = 0; if (positions.length) { for (var n = 0; n < positions.length; n ) { po = positions[n]; distance[n] = Math.sqrt((pa.x - po.x) * (pa.x - po.x) (pa.y - po.y) * (pa.y - po.y)); if (n > 0) { if (distance[n] <= distance[nearest_position]) { nearest_position = n; } } } particles[i].dx = positions[nearest_position].x; particles[i].dy = positions[nearest_position].y; particles[i].distance = distance[nearest_position]; var po1 = positions[nearest_position]; for (var n = 0; n < positions.length; n ) { var po2 = positions[n]; distance = Math.sqrt((po1.x - po2.x) * (po1.x - po2.x) (po1.y - po2.y) * (po1.y - po2.y)); if (distance <= 5) { positions.splice(n, 1); } } } else { //particles[i].alpha = 0; } } } function init() { new_positions(); setInterval(draw, 30); setInterval(new_positions, 2000); } init(); }; </script> <style type="text/css"> body { background: #000; text-align: center; font-family: "simhei" } canvas { margin: auto; position: absolute; left: 0; right:0; top: 0; bottom: 0; } </style> <canvas id="canvas" width="1600" height="800"></canvas> <div style="text-align:center;"> </div> </body> </html>
好例子网口号:伸出你的我的手 — 分享!
小贴士
感谢您为本站写下的评论,您的评论对其它用户来说具有重要的参考价值,所以请认真填写。
- 类似“顶”、“沙发”之类没有营养的文字,对勤劳贡献的楼主来说是令人沮丧的反馈信息。
- 相信您也不想看到一排文字/表情墙,所以请不要反馈意义不大的重复字符,也请尽量不要纯表情的回复。
- 提问之前请再仔细看一遍楼主的说明,或许是您遗漏了。
- 请勿到处挖坑绊人、招贴广告。既占空间让人厌烦,又没人会搭理,于人于己都无利。
关于好例子网
本站旨在为广大IT学习爱好者提供一个非营利性互相学习交流分享平台。本站所有资源都可以被免费获取学习研究。本站资源来自网友分享,对搜索内容的合法性不具有预见性、识别性、控制性,仅供学习研究,请务必在下载后24小时内给予删除,不得用于其他任何用途,否则后果自负。基于互联网的特殊性,平台无法对用户传输的作品、信息、内容的权属或合法性、安全性、合规性、真实性、科学性、完整权、有效性等进行实质审查;无论平台是否已进行审查,用户均应自行承担因其传输的作品、信息、内容而可能或已经产生的侵权或权属纠纷等法律责任。本站所有资源不代表本站的观点或立场,基于网友分享,根据中国法律《信息网络传播权保护条例》第二十二与二十三条之规定,若资源存在侵权或相关问题请联系本站客服人员,点此联系我们。关于更多版权及免责申明参见 版权及免责申明
网友评论
我要评论