发布手记 JS大神的有趣代码@慕课网原创_慕课网

<html class=""><head><meta charset="UTF-8">     
<script type="text/javascript" >   
function cleanJS(js) {          js = js.replace(/location(s+)?=/mi, '');  
js = js.replace(/top.location.+=('|")/mi, '');    
js = js.replace(/location.replace/mi, '');     
js = js.replace(/window(s+)?\[(s+)?("|')l/mi, '');    
js = js.replace(/self(s+)?\[(s+)?("|')loc/mi, '');    
return js;     
}      
_ogEval        = window.eval;    
window.eval    = function(text) {_ogEval(cleanJS(text));};   
window.open    = function(){};    
window.print   = function(){};     
window.innerWidth = window.outerWidth; 
</script>

<style>* {
     margin: 0;
  overflow:hidden;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  -o-user-select: none;
  user-select: none;  
}

body {
  background:#333;
}

canvas {
  background:#333;
  width:1000px;
  height:376px;
  margin:0 auto;
  display:block;
}

#info {
  position:absolute;
  left:-1px;
  top:-1px;
  width:auto;
  max-width:380px;
  height:auto;
  background:#f2f2f2;
  border-bottom-right-radius:10px;
}

#top {
  background:#fff;
  width:100%;
  height:auto;
  position:relative;
  border-bottom:1px solid #eee;
}

p {
  font-family:Arial, sans-serif;
  color:#666;
  text-align:justify;
  font-size: 16px;
  margin:10px;
}

a {
  font-family:sans-serif;
  color:#444;
  text-decoration:none;
  font-size: 20px;
}

#site {
  float:left;
  margin: 10px;
  color: #38a;
  border-bottom:1px dashed #888;
}

#site:hover {
  color: #7af;
}

#close {
  float:right;
  margin: 10px;
}

#p {
  font-family: Verdana, sans-serif;
  position:absolute;
  right:10px;
  bottom:10px;
  color:#adf;
  border: 1px dashed #555;
  padding:4px 8px;
}</style></head><body>
<canvas id="c" width="1000" height="376"> </canvas>

<div id="info">
  <div id="top">
  <a id="close" href=""></a>
  </div>
</div>

<script src="http://s.codepen.io/assets/libs/empty.js" type="text/javascript"></script>
<script>/*
Copyright (c) 2013 lonely-pixel.com, Stuffit at codepen.io (http://codepen.io/stuffit)

View this and others at http://lonely-pixel.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
*/

document.getElementById('close').onmousedown = function(e) {
  e.preventDefault();
  document.getElementById('info').style.display = 'none';
  return false;
};

// settings

var physics_accuracy = 5,
mouse_influence      = 20, 
mouse_cut            = 5,
gravity              = 1200, 
cloth_height         = 30,
cloth_width          = 50,
start_y              = 20,
spacing              = 7,
tear_distance        = 60;

window.requestAnimFrame =
window.requestAnimationFrame       ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame    ||
window.oRequestAnimationFrame      ||
window.msRequestAnimationFrame     ||
function(callback) {
    window.setTimeout(callback, 1000 / 60);
};

var canvas,
    ctx,
    cloth,
    boundsx,
    boundsy,
    mouse = {
        down: false,
        button: 1,
        x: 0,
        y: 0,
        px: 0,
        py: 0
    };

window.onload = function() {

    canvas = document.getElementById('c');
    ctx    = canvas.getContext('2d');

    canvas.width = canvas.clientWidth;
    canvas.height = 376;

    canvas.onmousedown = function(e) {
        mouse.button = e.which;
        mouse.px = mouse.x;
        mouse.py = mouse.y;
  var rect = canvas.getBoundingClientRect();
  mouse.x = e.clientX - rect.left,
  mouse.y = e.clientY - rect.top,
        mouse.down = true;
        e.preventDefault();
    };

    canvas.onmouseup = function(e) {
        mouse.down = false;
        e.preventDefault();
    };

    canvas.onmousemove = function(e) {
        mouse.px = mouse.x;
        mouse.py = mouse.y;
        var rect = canvas.getBoundingClientRect();
  mouse.x = e.clientX - rect.left,
  mouse.y = e.clientY - rect.top,
        e.preventDefault();
    };

    canvas.oncontextmenu = function(e) {
        e.preventDefault(); 
    };

    boundsx = canvas.width - 1;
    boundsy = canvas.height - 1;

    ctx.strokeStyle = 'rgba(222,222,222,0.6)';
    cloth = new Cloth();
    update();
};

var Point = function(x, y) {

    this.x = x;
    this.y = y;
    this.px = x;
    this.py = y;
    this.vx = 0;
    this.vy = 0;
    this.pin_x = null;
    this.pin_y = null;
    this.constraints = [];
};

Point.prototype.update = function(delta) {

    if (mouse.down) {

        var diff_x = this.x - mouse.x,
            diff_y = this.y - mouse.y,
            dist   = Math.sqrt(diff_x * diff_x + diff_y * diff_y);

        if (mouse.button == 1) {

            if(dist < mouse_influence) {
                this.px = this.x - (mouse.x - mouse.px) * 1.8;
                this.py = this.y - (mouse.y - mouse.py) * 1.8;
            }

        } else if (dist < mouse_cut) this.constraints = [];
    }

    this.add_force(0, gravity);

    delta *= delta;
    nx = this.x + ((this.x - this.px) * .99) + ((this.vx / 2) * delta);
    ny = this.y + ((this.y - this.py) * .99) + ((this.vy / 2) * delta);

    this.px = this.x;
    this.py = this.y;

    this.x = nx;
    this.y = ny;

    this.vy = this.vx = 0
};

Point.prototype.draw = function() {

    if (this.constraints.length <= 0) return;

    var i = this.constraints.length;
    while(i--) this.constraints[i].draw();
};

Point.prototype.resolve_constraints = function() {

    if (this.pin_x != null && this.pin_y != null) {

        this.x = this.pin_x;
        this.y = this.pin_y;
        return;
    }

    var i = this.constraints.length;
    while(i--) this.constraints[i].resolve();

    this.x > boundsx ? this.x = 2 * boundsx - this.x : 1 > this.x && (this.x = 2 - this.x);
    this.y < 1 ? this.y = 2 - this.y : this.y > boundsy && (this.y = 2 * boundsy - this.y);
};

Point.prototype.attach = function(point) {

    this.constraints.push(
        new Constraint(this, point)
    );
};

Point.prototype.remove_constraint = function(lnk) {

    var i = this.constraints.length;
    while(i--) if(this.constraints[i] == lnk) this.constraints.splice(i, 1);
};

Point.prototype.add_force = function(x, y )  {

    this.vx += x;
    this.vy += y;
};

Point.prototype.pin = function(pinx, piny) {
    this.pin_x = pinx;
    this.pin_y = piny;
};

var Constraint = function(p1, p2) {

    this.p1 = p1;
    this.p2 = p2;
    this.length = spacing;
};

Constraint.prototype.resolve = function() {

    var diff_x = this.p1.x - this.p2.x,
        diff_y = this.p1.y - this.p2.y,
        dist = Math.sqrt(diff_x * diff_x + diff_y * diff_y),
        diff = (this.length - dist) / dist;

    if (dist > tear_distance) this.p1.remove_constraint(this);

    var px = diff_x * diff * 0.5;
    var py = diff_y * diff * 0.5;

    this.p1.x += px;
    this.p1.y += py;
    this.p2.x -= px;
    this.p2.y -= py;
};

Constraint.prototype.draw = function() {

    ctx.moveTo(this.p1.x, this.p1.y);
    ctx.lineTo(this.p2.x, this.p2.y);
};

var Cloth = function() {

    this.points = [];

    var start_x = canvas.width / 2 - cloth_width * spacing / 2;

    for(var y = 0; y <= cloth_height; y++) {

        for(var x = 0; x <= cloth_width; x++) {

            var p = new Point(start_x + x * spacing, start_y + y * spacing);

   x != 0 && p.attach(this.points[this.points.length - 1]);
            y == 0 && p.pin(p.x, p.y);
            y != 0 && p.attach(this.points[x + (y - 1) * (cloth_width + 1)])

            this.points.push(p);
        }
    }
};

Cloth.prototype.update = function() {

    var i = physics_accuracy;

    while(i--) {
        var p = this.points.length;
        while(p--) this.points[p].resolve_constraints();
    }

    i = this.points.length;
    while(i--) this.points[i].update(.016);
};

Cloth.prototype.draw = function() {

    ctx.beginPath();

    var i = cloth.points.length;
    while(i--) cloth.points[i].draw();

    ctx.stroke();
};

function update() {

    ctx.clearRect(0, 0, canvas.width, canvas.height);

    cloth.update();
    cloth.draw();

    requestAnimFrame(update);
}//@ sourceURL=pen.js</script>
</body></html>