好玩代码,博客上很火的网站粒子背景特效canvas

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扫一扫,直接在手机上打开

至少朋友说还是挺酷炫的。这种效果其实很早之前就有了的,我也是在一个网站上看到类似的效果,发现这个创意不错,而且难度很小,就花了一个午休的时间写了一下。


本站是直接写入footer.php来实现的。


也可以直接打包成js文件再引入,不会占用太大内存。

未压缩版以方便查看:

  1. ! 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 all_array = [current_point].concat(random_lines);    
            var e, i, d, x_dist, y_dist, dist; //临时节点    
            //遍历处理每一个点    
            random_lines.forEach(function(r) {    
                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    
                for (i = 0; i < all_array.length; i++) {    
                    e = all_array[i];    
                    //不是当前点    
                    if (r !== e && 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 / 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());    
                    }    
                }    
                all_array.splice(all_array.indexOf(r), 1);    
        
            }), 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    
            };    
        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_lines = [], 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;    
            random_lines.push({    
                x: x,    
                y: y,    
                xa: xa,    
                ya: ya,    
                max: 6000 //沾附距离    
            });    
        }    
        //0.1秒后绘制    
        setTimeout(function() {    
            draw_canvas();    
        }, 100);    
    }();    
the end
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