js特效

# 一段js特效的代码# 使用方法：粘贴到页脚代码<script type="text/javascript"> ! function() { ?//封装方法，压缩之后减少文件大小 ?function get_attribute(node, attr, default_value) { ???return node.getAttribute(attr) || default_value; ?} ?//封装方法，压缩之后减少文件大小 ?function get_by_tagname(name) { ???return document.getElementsByTagName(name); ?} ?//获取配置参数 ?function get_config_option() { ???var scripts = get_by_tagname("script"), ?????script_len = scripts.length, ?????script = scripts[script_len - 1]; //当前加载的script ???return { ?????l: script_len, //长度，用于生成id用 ?????z: get_attribute(script, "zIndex", -1), //z-index ?????o: get_attribute(script, "opacity", 0.5), //opacity ?????c: get_attribute(script, "color", "0,0,0"), //color ?????n: get_attribute(script, "count", 99) //count ???}; ?} ?//设置canvas的高宽 ?function set_canvas_size() { ???canvas_width = the_canvas.width = window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth, ???canvas_height = the_canvas.height = window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight; ?} ??//绘制过程 ?function draw_canvas() { ???context.clearRect(0, 0, canvas_width, canvas_height); ???//随机的线条和当前位置联合数组 ???var e, i, d, x_dist, y_dist, dist; //临时节点 ???//遍历处理每一个点 ???random_points.forEach(function(r, idx) { ?????r.x += r.xa, ?????r.y += r.ya, //移动 ?????r.xa *= r.x > canvas_width || r.x < 0 ? -1 : 1, ?????r.ya *= r.y > canvas_height || r.y < 0 ? -1 : 1, //碰到边界，反向反弹 ?????context.fillRect(r.x - 0.5, r.y - 0.5, 1, 1); //绘制一个宽高为1的点 ?????//从下一个点开始 ?????for (i = idx + 1; i < all_array.length; i++) { ???????e = all_array[i]; ???????// 当前点存在 ???????if (null !== e.x && null !== e.y) { ?????????x_dist = r.x - e.x; //x轴距离 l ?????????y_dist = r.y - e.y; //y轴距离 n ?????????dist = x_dist * x_dist + y_dist * y_dist; //总距离, m ??????????dist < e.max && (e === current_point && dist >= e.max / 2 && (r.x -= 0.03 * x_dist, r.y -= 0.03 * y_dist), //靠近的时候加速 ???????????d = (e.max - dist) / e.max, ???????????context.beginPath(), ???????????context.lineWidth = d / 2, ???????????context.strokeStyle = "rgba(" + config.c + "," + (d + 0.2) + ")", ???????????context.moveTo(r.x, r.y), ???????????context.lineTo(e.x, e.y), ???????????context.stroke()); ???????} ?????} ???}), frame_func(draw_canvas); ?} ?//创建画布，并添加到body中 ?var the_canvas = document.createElement("canvas"), //画布 ???config = get_config_option(), //配置 ???canvas_id = "c_n" + config.l, //canvas id ???context = the_canvas.getContext("2d"), canvas_width, canvas_height, ???frame_func = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function(func) { ?????window.setTimeout(func, 1000 / 45); ???}, random = Math.random, ???current_point = { ?????x: null, //当前鼠标x ?????y: null, //当前鼠标y ?????max: 20000 // 圈半径的平方 ???}, ???all_array; ?the_canvas.id = canvas_id; ?the_canvas.style.cssText = "position:fixed;top:0;left:0;z-index:" + config.z + ";opacity:" + config.o; ?get_by_tagname("body")[0].appendChild(the_canvas); ??//初始化画布大小 ?set_canvas_size(); ?window.onresize = set_canvas_size; ?//当时鼠标位置存储，离开的时候，释放当前位置信息 ?window.onmousemove = function(e) { ???e = e || window.event; ???current_point.x = e.clientX; ???current_point.y = e.clientY; ?}, window.onmouseout = function() { ???current_point.x = null; ???current_point.y = null; ?}; ?//随机生成config.n条线位置信息 ?for (var random_points = [], i = 0; config.n > i; i++) { ???var x = random() * canvas_width, //随机位置 ?????y = random() * canvas_height, ?????xa = 2 * random() - 1, //随机运动方向 ?????ya = 2 * random() - 1; ???// 随机点 ???random_points.push({ ?????x: x, ?????y: y, ?????xa: xa, ?????ya: ya, ?????max: 6000 //沾附距离 ???}); ?} ?all_array = random_points.concat([current_point]); ?//0.1秒后绘制 ?setTimeout(function() { ???draw_canvas(); ?}, 500);}();</script><canvas id="c_n5" width="1366" height="276" style="position: fixed; top: 0px; left: 0px; z-index: -1; opacity: 0.5;"></canvas>