/**
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* barnsley-fern.js
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* Plot a Barnsley fern to the JXG Board
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*/
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import "./lib/dfhi.js";
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import * as JXG from "jsxgraph" ;
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import {exportBoard} from "./lib/dfhi-plot";
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/**
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* the JXG Board
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* */
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let board = undefined;
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/**
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* called only once, as page loaded, as required by "lib/dfhi.js" API
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* */
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window.init = function() {
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board = initBoard();
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function exportSvg(event) {
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exportBoard(board);
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}
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document.getElementById("export")
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.addEventListener("click", exportSvg);
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};
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/**
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* called every time user clicks on the #run Button, as required by "lib/dfhi.js"
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* */
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window.main = function(...argv) {
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if (board) {
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try {
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JXG.JSXGraph.freeBoard(board);
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board = undefined;// remove all child of boad
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board = initBoard();
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}catch (e) {
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console.log(e);
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console.log(board);
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}
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}
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let n = Number.parseInt(argv[0]);
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let points = barnsley(n);
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let opt = {withLabel:false, fixed:true, size:0.001, fillColor:"#00aa00", strokeWidth:0};
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plotBarnsley(board, points, opt);
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};
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/**
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* init board, called at least once by window.init
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* */
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function initBoard() {
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return JXG.JSXGraph.initBoard('plotter', {
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boundingbox: [-6, 12, 6, -1],
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axis: false,
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keepAspectRatio:true
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});
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}
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/**
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* generates points of Barnsley Fern.
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* */
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function barnsley(n) {
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const m = [
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[ 0 , 0 , 0 , 0.16 , 0.500 , 0 , 0.01],
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[ 0.85 , 0.04 , -0.04 , 0.85 , 0.075 , 1.60 , 0.85],
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[ 0.20 , -0.26 , 0.23 , 0.22 , 0.400 , 1.60 , 0.07],
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[-0.15 , 0.28 , 0.26 , 0.24 , 0.575 , 0.44 , 0.07]
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];
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const p = [ m[0][6], m[0][6] + m[1][6], m[0][6] + m[1][6] + m[2][6] ];
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let x = 0, y = 0;
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const points = [ [x, y] ];
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for(let i = 0; i < n; ++i) {
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let r = Math.random();
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let f = 0;
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if (r < p[0]) {
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f = 0;
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}else if (r < p[1]) {
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f = 1;
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}else if (r < p[2]) {
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f = 2;
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} else {
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f = 3;
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}
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let nX = (m[f][0] * x) + (m[f][1] * y) + m[f][4];
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y = (m[f][2] * x) + (m[f][3] * y) + m[f][5];
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x = nX;
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points.push([x,y]);
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}
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return points;
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}
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/**
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*
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* @param board
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* @param points
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* @param attr
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*
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* */
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function plotBarnsley(board, points, attr ) {
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for(let p of points) {
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board.create('point', p, attr );
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}
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}
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