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html5特效-用Canvas模拟可撕裂布料效果

这是一款借助 Canvas 的强大绘图和动画功能模拟可撕裂布料的html5特效,完整源码下载链接: http://pan.baidu.com/s/1kVG0dfx 密码: 65d6

效果预览图:

HTML5 Canvas 模拟可撕裂布料效果

HTML5 Canvas 模拟可撕裂布料效果

index.html代码

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>HTML5 Canvas可撕裂布料效果</title>
<link rel="stylesheet" type="text/css" href="style.css" />
<style>
.top-banner {
background-color: #666;
}
a {
font-size: 13px;
}
#info {
position: absolute;
left: -1px;
top: 30px;
}
#c {
display: block;
margin: 60px auto 0;
}
</style>
</head>
<body>
<canvas id="c"></canvas>
<div id="info">
<p>
<br>- 使用鼠标可以拉扯
<br>
<br>- 右键可以切断布料
<br>
<br>
</p>
</div>
<script type="text/javascript" src="Cloth.js"></script>
</body>
</html>

style.css代码:

* {
 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: 380px;
 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;
}
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: #167fc6;
 border: 1px dashed #555;
 padding: 4px 8px;
}

Cloth.js代码

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 <= 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(); if (this.x > boundsx) {

        this.x = 2 * boundsx - this.x;
        
    } else if (this.x < 1) { this.x = 2 - this.x; } if (this.y > boundsy) {

        this.y = 2 * boundsy - this.y;
        
    } else if (this.y < 1) { this.y = 2 - 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);
}

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();
};

 

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