canvas绚丽布料背景效果代码-html代码-BFW代码库

代码语言：html

所属分类：背景

代码描述：canvas绚丽布料背景效果代码，点击更换不同的风格与颜色

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>
body {
  font-family: Arial, Helvetica, "Liberation Sans", FreeSans, sans-serif;
  background-color: #000;
  margin:0;
  padding:0;
  border-width:0;
  cursor: pointer;
}
</style>


</head>

<body>
  <!-- 
Click for new drawing 
-->

      <script >
"use strict";

window.addEventListener("load", function () {

  const SPEED_ANIM = 5;

  let canv, ctx; // canvas and context
  let maxx, maxy; // canvas dimensions

  // for animation
  let events;

  // shortcuts for Math.
  const mrandom = Math.random;
  const mfloor = Math.floor;
  const mround = Math.round;
  const mceil = Math.ceil;
  const mabs = Math.abs;
  const mmin = Math.min;
  const mmax = Math.max;

  const mPI = Math.PI;
  const mPIS2 = Math.PI / 2;
  const mPIS3 = Math.PI / 3;
  const m2PI = Math.PI * 2;
  const m2PIS3 = Math.PI * 2 / 3;
  const msin = Math.sin;
  const mcos = Math.cos;
  const matan2 = Math.atan2;

  const mhypot = Math.hypot;
  const msqrt = Math.sqrt;

  const rac3 = msqrt(3);
  const rac3s2 = rac3 / 2;

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

  function alea(mini, maxi) {
    // random number in given range

    if (typeof maxi == 'undefined') return mini * mrandom(); // range 0..mini

    return mini + mrandom() * (maxi - mini); // range mini..maxi
  }
  // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  function intAlea(mini, maxi) {
    // random integer in given range (mini..maxi - 1 or 0..mini - 1)
    //
    if (typeof maxi == 'undefined') return mfloor(mini * mrandom()); // range 0..mini - 1
    return mini + mfloor(mrandom() * (maxi - mini)); // range mini .. maxi - 1
  }

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

  function Noise1DOneShot(period, min = 0, max = 1, random) {
    /* returns a 1D single-shot noise generator.
                                                                the (optional) random function must return a value between 0 and 1
                                                               the returned function has no parameter, and will return a new number every tiime it is called.
                                                               If the random function provides reproductible values (and is not used elsewhere), this
                                                               one will return reproductible values too.
                                                               period should be > 1. The bigger period is, the smoother output noise is
                                                             */
    random = random || Math.random;
    let currx = random(); // start with random offset
    let y0 = min + (max - min) * random(); // 'previous' value
    let y1 = min + (max - min) * random(); // 'next' value
    let dx = 1 / period;

    return function () {
      currx += dx;
      if (currx > 1) {
        currx -= 1;
        y0 = y1;
        y1 = min + (max - min) * random();
      }
      let z = (3 - 2 * currx) * currx * currx;
      return z * y1 + (1 - z) * y0;
    };
  } // Noise1DOneShot

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

  function drawBezierArc(p0, p1, p2, p3) {
    // draws a Bezier quadratic curve between p1 and p2
    // tangent at point p1 is paralel to p0-p2
    // tangent at point p2 is paralel to p1-p3

    let dx, dy, lngth, ltg, lctrl;
    let x1c, y1c; // coordinates of 1st control point
    let x2c, y2c; // coordinates of 2nd control point

    const coeffDir = 0.3; // coefficient for distance of control points

    lngth = mhypot(p2[0] - p1[0], p2[1] - p1[1]);

    lctrl = lngth * coeffDir;

    // 1st control point

    dx = p2[0] - p0[0];
    dy = p2[1] - p0[1];
    ltg = mhypot(dx, dy);
    x1c = p1[0] + lctrl * dx / ltg;
    y1c = p1[1] + lctrl * dy / ltg;

    // 2nd control point

    dx = p1[0] - p3[0];
    dy = p1[1] - p3[1];
    ltg = mhypot(dx, dy);
    x2c = p2[0] + lctrl * dx / ltg;
    y2c = p2[1] + lctrl * dy / ltg;

    ctx.bezierCurveTo(x1c, y1c,
    x2c, y2c,
    p2[0], p2[1]);

  } // function drawBezierArc

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

  function Blob(xc, yc, radiusMax, nbSteps, lineWidth, hue) {

    this.xc = xc;
    this.yc = yc;
    this.radiusMax = radiusMax;
    this.nbSteps = nbSteps;
    this.lineWidth = lineWidth;

    let nbPts = this.nbPts = intAlea(4, 10);
    this.th0 = alea(m2PI); // global direction offset

    /* create points around center
      points are given by direction (relative to th0) and radius
      radius here is relative to radius given at draw time.
    */
    let deltadir = m2PI / nbPts; // average angle.........完整代码请登录后点击上方下载按钮下载查看