以前在前端网收藏的一个好玩特效分享给大家
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>模拟可撕裂布料效果</title>
<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: #F2F2F2;
}
#c {
display: block;
margin: 20px auto 0;
}
#info {
position: absolute;
left: -1px;
top: -1px;
width: auto;
max-width: 420px;
height: auto;
background: #f2f2f2;
border-bottom-right-radius: 10px;
border: 1px solid #333;
}
#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 16px;
}
#github {
color: #3377ee;
font-family: Helvetica, Arial, sans-serif;
font-size: 19px;
display: block;
margin: 0 auto;
text-align: center;
text-decoration: none;
}
#net {
text-align: center;
white-space: nowrap;
font-size: 19px;
background: rgba(0, 0, 0, 0.1);
padding: 8px 12px;
border-radius: 8px;
display: block;
color: #888;
}
#net>span {
color: #3377ee;
font-family: Helvetica, Arial, sans-serif;
font-size: 14px;
display: block;
margin: 0 auto;
text-align: center;
text-decoration: none;
}
a {
font-family: sans-serif;
color: #444;
text-decoration: none;
font-size: 20px;
}
#site {
float: left;
margin: 10px;
color: #ff9900;
border-bottom: 1px dashed #ccc;
padding-bottom: 3px
}
#site:hover {
color: #ffaa11;
}
#close {
float: right;
margin: 10px;
}
#p {
font-family: Verdana, sans-serif;
position: absolute;
right: 10px;
bottom: 10px;
color: #4099ff;
border: 1px dashed #4099ff;
padding: 4px 8px;
}
#irc {
display: block;
text-align: center;
margin-top: 4px;
color: #333;
}
#irc a {
color: #3377ee;
font-size: 17px
}
#irc-info {
display: block;
text-align: center;
font-size: 14px;
margin-top: -10px;
color: #828282;
margin-bottom: 4px
}
#new {
width: 100%;
text-align: center;
font-size: 18px;
font-family: Helvetica;
}
#new a {
font-size: 18px;
color: #4099ff;
}
</style>
</head>
<body>
<canvas id="c"></canvas>
<script>
var physics_accuracy = 3, 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
};
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)
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(constraint) {
this.constraints.splice(this.constraints.indexOf(constraint), 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);
}
function start() {
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 = '#888';
cloth = new Cloth();
update();
}
window.onload = function() {
canvas = document.getElementById('c');
ctx = canvas.getContext('2d');
canvas.width = 560;
canvas.height = 350;
start();
};
</script>
</body>
</html>
