js canvas模拟物理物体摇摆动画效果代码-html代码-BFW代码库

代码语言：html

所属分类：动画

代码描述：js canvas模拟物理物体摇摆动画效果代码，拖动物体关节处看效果

下面为部分代码预览，完整代码请点击下载或在bfwstudio webide中打开


<!DOCTYPE html>
<html lang="en" >

<head>

  <meta charset="UTF-8">
  

  
  
  
  
<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:340px;
  margin:0 auto;
  display:block;
  border:1px dashed #555;
  border-top:none;
}

#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;
  line-height:22px;
  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 #bbf;
  padding-bottom:3px
}

#close {
  float:right;
  margin: 10px;
}
</style>




</head>

<body  >
  <canvas id = "c"></canvas>

<div id="info">
  <div id="top">
  <a id="close" href="">close</a>
  </div>
  <p>
    - Left click to drag points (corners, joints etc).<br>
    - Right click to delete a point.<br>
    - Hold ctrl to enter edit mode, release to exit.<br><br>
      &nbsp;&nbsp;<strong>When in edit mode:</strong><br>
    - Click to add points, hold alt to make fixed points.<br>
    - New points will join to the last point by default.<br>
    - Press shift to unselect a point.<br>
    - Select any two points to join them.<br>
  </p>
</div>

      <script  >
/*
Copyright (c) 2013 dissimulate at codepen

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;
};

var two_PI = Math.PI * 2;

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

//-------------------------------------------------

var Vector = function (x, y) {

  this.x = x || 0;
  this.y = y || 0;
};

Vector.prototype.sub = function (v) {

  if (v.x != null && v.y != null) {

    this.x -= v.x;
    this.y -= v.y;

  } else {

    this.x -= v;
    this.y -= v;
  }

  return this;
};

Vector.prototype.add = function (v) {

  if (v.x != null && v.y != null) {

    this.x += v.x;
    this.y += v.y;

  } else {

    this.x += v;
    this.y += v;
  }

  return this;
};

Vector.prototype.mul = function (v) {

  if (v.x != null && v.y != null) {

    this.x *= v.x;
    this.y *= v.y;

  } else {

    this.x *= v;
    this.y *= v;
  }

  return this;
};

Vector.prototype.div = function (v) {

  if (v.x != null && v.y != null) {

    this.x /= v.x;
    this.y /= v.y;

  } else {

    this.x /= v;
    this.y /= v;
  }

  return this;
};

Vector.prototype.normalize = function () {

  var length = this.length();

  if (length > 0) {
    this.x /= length;
    this.y /= length;
  }

  return this;
};

Vector.prototype.length = function () {

  return Math.sqrt(this.x * this.x + this.y * this.y);
};

Vector.prototype.distance = function (v) {

  var x = this.x - v.x;
  var y = this.y - v.y;

  return Math.sqrt(x * x + y * y);
};

Vector.prototype.reset = function () {

  this.x = 0;
  this.y = 0;

  return this;
};

Vector.prototype.neg = function () {

  this.x *= -1;
  this.y *= -1;

  return this;
};

Vector.add = function (v1, v2) {

  if (v2.x != null && v2.y != null) {

    return new Vector(
    v1.x + v2.x,
    v1.y + v2.y);

  } else {

    return new Vector(
    v1.x + v2,
    v1.y + v2);
  }
};

Vector.sub = function (v1, v2) {

  if (v2.x != null && v2.y != null) {

    return new Vector(
    v1.x - v2.x,
    v1.y - v2.y);

  } else {

    return new Vector(
    v1.x - v2,
    v1.y - v2);
  }
};

Vector.mul = function (v1, v2) {

  if (v2.x != null && v2.y != null) {

    return new Vector(
    v1.x * v2.x,
    v1.y * v2.y);

  } else {

    return new Vector(
    v1.x * v2,
    v1.y * v2);
  }
};

Vector.div = function (v1, v2) {

  if (v2.x != null && v2.y != null) {

    return new Vector(
    v1.x / v2.x,
    v1.y / v2.y);

  } else {

    return new Vector(
    v1.x / v2,
    v1.y / v2);
  }
};

//-------------------------------------------------

var Point = function (x, y, fixed) {

  this.pos = new Vector(x, y);
  this.pre = new Vector(x, y);
  this.acc = new Vector();

  this.fixed = fixed;
};

Point.prototype.move = function (v) {

  if (this.fixed) return;

  this.pos.add(v);
};

Point.prototype.add_force = function (v) {

  if (this.fixed) return;

  this.acc.add(v);
};

Point.prototype.update = function (delta) {

  if (this.fixed) return;

  delta *= delta;

  var x = this.pos.x,
  y = this.pos.y;

  this.acc.mul(delta);

  this.pos.x += x - this.pre.x + this.acc.x;
  this.pos.y += y - this.pre.y + this.acc.y;

  this.acc.reset();

  this.pre.x = x;
  this.pre.y = y;
};

Point.prototype.check_walls = function (x, y, w, h) {

  this.pos.x = Math.max(x + 1, Math.min(w - 1, this.pos.x));
  this.pos.y = Math.max(y + 1, Math.min(h - 1, this.pos.y));

  if (this.pos.y >= h - 1)
  this.pos.x -= this.pos.x - this.pre.x + this.acc.x;
};

Point.prototype.draw = function (ctx, size) {

  if (this.fixed) {

    ctx.fillStyle = 'rgba(255,255,255,0.2)';
    ctx.beginPath();
    ctx.arc(this.pos.x, this.pos.y, size * 3, 0, two_PI, false);
    ctx.fill();
  }

  ctx.fillStyle = this.fixed ? '#EDEA26' : '#aaa';
  ctx.beginPath();
  ctx.arc(this.pos.x, this.pos.y, size, 0, two_PI, false);
  ctx.fill();
};

//-------------------------------------------------

var Constraint = function (p1, p2) {

  this.p1 = p1;
  this.p2 = p2;
  this.length = p1.pos.distance(p2.pos);
  this.stretch = this.length * 0.15;
};

Constraint.prototype.resolve = function () {

  var dists = Vector.sub(this.p2.pos, this.p1.pos),
  length = dists.length(),
  diff = length - this.length;

  dists.normalize();

  var f = dists.mul(diff * 0.5);

  this.p1.move(f);
  this.p2.move(f.neg());
};

Constraint.prototype.draw = function (ctx, stress) {

  if (stress) {

    var diff = this.length - this.p1.pos.distance(this.p2.pos);

    var per = Math.round(Math.min(Math.abs(diff / this.stretch), 1) * 255);

    ctx.strokeStyle = 'rgba(255, ' + (255 - per) + ', ' + (255 - per) + ', 0.8)';

  } else ctx.strokeStyle = 'rgba(255,255,255,0.8)';

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

//-------------------------------------------------

var JSVerlet = function (canvas, options) {

  this.canvas = canvas;
  this.ctx = canvas.getContext('2d');
  this.ctx.lineWidth = 1;

  this.width = canvas.width;
  this.height = canvas.height;
  this.options = options || {};

  this.constraints = [];
  this.points = [];
  this.draw_points = [];

  this.mouse = new Vector();
  this.gravity = this.options.gravity || new Vector(0, 0.98);
  this.point_size = this.options.point_size || 2;
  this.show_stress = this.options.show_stress;

  this.key.........完整代码请登录后点击上方下载按钮下载查看