canvas模拟月球表面石坑渐变效果-html代码-BFW代码库

代码语言：html

所属分类：背景

代码描述：canvas模拟月球表面石坑渐变效果

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">


</head>
<body translate="no">


<script>
"use strict";

/**** parameters you should try to modify */

const minRadius = 7;
const maxRadius = 100;
const margin = 3; // minimum distance between 2 circles

/**** modifications beyond this line at your own risk */

let canv, ctx;
let maxx, maxy; // canvas sizes (in pixels)

let circles;
let letConcentric;

let events = [];
let mouse = {};

// 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 m2PI = Math.PI * 2;
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;
const mPIS3 = Math.PI / 3;

//-----------------------------------------------------------------------------
// miscellaneous functions
//-----------------------------------------------------------------------------

function alea(min, max) {
  // random number [min..max[ . If no max is provided, [0..min[

  if (typeof max == 'undefined') return min * mrandom();
  return min + (max - min) * mrandom();
}

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

function intAlea(min, max) {
  // random integer number [min..max[ . If no max is provided, [0..min[

  if (typeof max == 'undefined') {
    max = min;min = 0;
  }
  return mfloor(min + (max - min) * mrandom());
} // intAlea

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
function arrayShuffle(array) {
  /* randomly changes the order of items in an array
                                 only the order is modified, not the elements
                              */
  let k1, temp;
  for (let k = array.length - 1; k >= 1; --k) {
    k1 = intAlea(0, k + 1);
    temp = array[k];
    array[k] = array[k1];
    array[k1] = temp;
  } // for k
  return array;
} // arrayShuffle

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
function length(p0, p1) {

  /* distance between points */

  return mhypot(p0[0] - p1[0], p0[1] - p1[1]);

} // function length

//-----------------------------------------------------------------------------
function Circle(x, y, radius) {
  this.c = [x, y];
  this.radius = radius;
} // Circle

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

Circle.prototype.draw = function (col1, col2) {

  let x0, y0, x1, y1;
  x0 = this.c[0];
  y0 = this.c[1] - this.radius;
  x1 = this.c[0];
  y1 = this.c[1] + this.radius;

  let linGrad = ctx.createLinearGradient(x0, y0, x1, y1);
  linGrad.addColorStop(0, col1);
  linGrad.addColorStop(1, col2);
  ctx.beginPath();
  ctx.arc(this.c[0], this.c[1], this.radius, 0, m2PI);
  ctx.fillStyle = linGrad;
  ctx.fill();
}; //

//------------------------------------------------------------------------
function createCircles() {

  let x, y, maxRad, d;

  letConcentric = mouse.y > maxy / 2;

  let limit = minRadius + margin;
  circles = []; // initially empty
  let failcnt = 0;
  retry:

  while (circles.length < 5000) {
    failcnt++;
    if (failcnt > 100) break; // 100 unsuccessful tries, give up

    x = alea(maxx);
    y = alea(maxy);
    maxRad = x;
    maxRad = mmin(maxRad, maxx - x);
    maxRad = mmin(maxRad, y);
    maxRad = mmin(maxRad, maxy - y);
    if (maxRad < limit) continue retry;
    for (let k = 0; k < .........完整代码请登录后点击上方下载按钮下载查看