<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
</head>
<body>
</body>
<script>
! function() {
//封裝方法，壓縮之後減少文件大小
function get_attribute(node, attr, default_value) {
return node.getAttribute(attr) || default_value;
}
//封裝方法，壓縮之後減少文件大小
function get_by_tagname(name) {
return document.getElementsByTagName(name);
}
//獲取配置參數
function get_config_option() {
var scripts = get_by_tagname("script"),
script_len = scripts.length,
script = scripts[script_len - 1]; //當前加載的script
return {
l: script_len, //長度，用於生成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", 500) //count
};
}
//設置canvas的高寬
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;
}
//繪製過程
function draw_canvas() {
context.clearRect(0, 0, canvas_width, canvas_height);
//隨機的線條和當前位置聯合數組
var e, i, d, x_dist, y_dist, dist; //臨時節點
//遍歷處理每一個點
random_lines.forEach(function(r, idx) {
r.x += r.xa,
r.y += r.ya, //移動
r.xa *= r.x > canvas_width || r.x < 0 ? -1 : 1,
r.ya *= r.y > canvas_height || r.y < 0 ? -1 : 1, //碰到邊界，反向反彈
context.fillRect(r.x - 0.5, r.y - 0.5, 1, 1); //繪製一個寬高爲1的點
//從下一個點開始
for (i = idx + 1; i < all_array.length; i++) {
e = all_array[i];
//不是當前點
if (null !== e.x && null !== e.y) {
x_dist = r.x - e.x, //x軸距離 l
y_dist = r.y - e.y, //y軸距離 n
dist = x_dist * x_dist + y_dist * y_dist; //總距離, m
dist < e.max && (e === current_point && dist >= e.max / 2 && (r.x -= 0.03 * x_dist, r.y -= 0.03 * y_dist), //靠近的時候加速
d = (e.max - dist) / e.max,
context.beginPath(),
context.lineWidth = d / 2,
context.strokeStyle = "rgba(" + config.c + "," + (d + 0.9) + ")",
context.moveTo(r.x, r.y),
context.lineTo(e.x, e.y),
context.stroke());
}
}
}), frame_func(draw_canvas);
}
//創建畫布，並添加到body中
var the_canvas = document.createElement("canvas"), //畫布
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, //當前鼠標x
y: null, //當前鼠標y
max: 20000
},
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);
//初始化畫布大小
set_canvas_size(), window.onresize = set_canvas_size;
//當時鼠標位置存儲，離開的時候，釋放當前位置信息
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;
};
//隨機生成config.n條線位置信息
for (var random_lines = [], i = 0; config.n > i; i++) {
var x = random() * canvas_width, //隨機位置
y = random() * canvas_height,
xa = 2 * random() - 1, //隨機運動方向
ya = 2 * random() - 1;
random_lines.push({
x: x,
y: y,
xa: xa,
ya: ya,
max: 6000 //沾附距離
});
}
all_array = random_lines.concat([current_point]);
//0.1秒後繪製
setTimeout(function() {
draw_canvas();
}, 0);
}();
</script>
</html>
js實現蜘蛛網效果
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