125 lines
2.9 KiB
JavaScript
125 lines
2.9 KiB
JavaScript
import Feature from '../src/ol/Feature.js';
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import Map from '../src/ol/Map.js';
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import _ol_View_ from '../src/ol/View.js';
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import LineString from '../src/ol/geom/LineString.js';
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import _ol_layer_Vector_ from '../src/ol/layer/Vector.js';
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import _ol_source_Vector_ from '../src/ol/source/Vector.js';
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var radius = 10e6;
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var cos30 = Math.cos(Math.PI / 6);
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var sin30 = Math.sin(Math.PI / 6);
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var rise = radius * sin30;
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var run = radius * cos30;
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var triangle = new LineString([
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[0, radius], [run, -rise], [-run, -rise], [0, radius]
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]);
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var feature = new Feature(triangle);
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var layer = new _ol_layer_Vector_({
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source: new _ol_source_Vector_({
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features: [feature]
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})
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});
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var map = new Map({
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layers: [layer],
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target: 'map',
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view: new _ol_View_({
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center: [0, 0],
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zoom: 1
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})
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});
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function makeFractal(depth) {
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var geometry = triangle.clone();
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var graph = coordsToGraph(geometry.getCoordinates());
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for (var i = 0; i < depth; ++i) {
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var node = graph;
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while (node.next) {
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var next = node.next;
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injectNodes(node);
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node = next;
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}
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}
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var coordinates = graphToCoords(graph);
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document.getElementById('count').innerHTML = coordinates.length;
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geometry.setCoordinates(coordinates);
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feature.setGeometry(geometry);
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}
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function injectNodes(startNode) {
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var endNode = startNode.next;
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var start = startNode.point;
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var end = startNode.next.point;
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var dx = end[0] - start[0];
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var dy = end[1] - start[1];
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// first point at 1/3 along the segment
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var firstNode = {
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point: [start[0] + dx / 3, start[1] + dy / 3]
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};
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// second point at peak of _/\_
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var r = Math.sqrt(dx * dx + dy * dy) / (2 * cos30);
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var a = Math.atan2(dy, dx) + Math.PI / 6;
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var secondNode = {
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point: [start[0] + r * Math.cos(a), start[1] + r * Math.sin(a)]
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};
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// third point at 2/3 along the segment
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var thirdNode = {
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point: [end[0] - dx / 3, end[1] - dy / 3]
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};
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startNode.next = firstNode;
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firstNode.next = secondNode;
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secondNode.next = thirdNode;
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thirdNode.next = endNode;
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}
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function coordsToGraph(coordinates) {
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var graph = {
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point: coordinates[0]
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};
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var length = coordinates.length;
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for (var level = 0, node = graph; level < length - 1; ++level) {
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node.next = {
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point: coordinates[level + 1]
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};
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node = node.next;
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}
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return graph;
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}
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function graphToCoords(graph) {
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var coordinates = [graph.point];
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for (var node = graph, i = 1; node.next; node = node.next, ++i) {
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coordinates[i] = node.next.point;
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}
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return coordinates;
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}
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var depthInput = document.getElementById('depth');
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function update() {
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makeFractal(Number(depthInput.value));
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}
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var updateTimer;
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/**
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* Regenerate fractal on depth change. Change events are debounced so updates
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* only occur every 200ms.
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*/
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depthInput.onchange = function() {
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window.clearTimeout(updateTimer);
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updateTimer = window.setTimeout(update, 200);
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};
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update();
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