147 lines
4.7 KiB
JavaScript
147 lines
4.7 KiB
JavaScript
function rotatePoints(points, center, degrees) {
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if (points && points.length) {
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const [cx, cy] = center;
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const angle = (Math.PI / 180) * degrees;
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const cos = Math.cos(angle);
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const sin = Math.sin(angle);
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for (const p of points) {
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const [x, y] = p;
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p[0] = ((x - cx) * cos) - ((y - cy) * sin) + cx;
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p[1] = ((x - cx) * sin) + ((y - cy) * cos) + cy;
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}
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}
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}
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function rotateLines(lines, center, degrees) {
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const points = [];
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lines.forEach((line) => points.push(...line));
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rotatePoints(points, center, degrees);
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}
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function areSamePoints(p1, p2) {
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return p1[0] === p2[0] && p1[1] === p2[1];
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}
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export function hachureLines(polygons, hachureGap, hachureAngle, hachureStepOffset = 1) {
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const angle = hachureAngle;
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const gap = Math.max(hachureGap, 0.1);
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const polygonList = (polygons[0] && polygons[0][0] && (typeof polygons[0][0] === 'number')) ? [polygons] : polygons;
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const rotationCenter = [0, 0];
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if (angle) {
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for (const polygon of polygonList) {
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rotatePoints(polygon, rotationCenter, angle);
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}
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}
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const lines = straightHachureLines(polygonList, gap, hachureStepOffset);
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if (angle) {
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for (const polygon of polygonList) {
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rotatePoints(polygon, rotationCenter, -angle);
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}
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rotateLines(lines, rotationCenter, -angle);
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}
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return lines;
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}
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function straightHachureLines(polygons, gap, hachureStepOffset) {
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const vertexArray = [];
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for (const polygon of polygons) {
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const vertices = [...polygon];
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if (!areSamePoints(vertices[0], vertices[vertices.length - 1])) {
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vertices.push([vertices[0][0], vertices[0][1]]);
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}
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if (vertices.length > 2) {
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vertexArray.push(vertices);
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}
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}
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const lines = [];
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gap = Math.max(gap, 0.1);
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// Create sorted edges table
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const edges = [];
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for (const vertices of vertexArray) {
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for (let i = 0; i < vertices.length - 1; i++) {
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const p1 = vertices[i];
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const p2 = vertices[i + 1];
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if (p1[1] !== p2[1]) {
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const ymin = Math.min(p1[1], p2[1]);
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edges.push({
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ymin,
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ymax: Math.max(p1[1], p2[1]),
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x: ymin === p1[1] ? p1[0] : p2[0],
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islope: (p2[0] - p1[0]) / (p2[1] - p1[1]),
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});
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}
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}
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}
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edges.sort((e1, e2) => {
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if (e1.ymin < e2.ymin) {
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return -1;
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}
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if (e1.ymin > e2.ymin) {
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return 1;
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}
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if (e1.x < e2.x) {
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return -1;
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}
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if (e1.x > e2.x) {
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return 1;
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}
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if (e1.ymax === e2.ymax) {
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return 0;
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}
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return (e1.ymax - e2.ymax) / Math.abs((e1.ymax - e2.ymax));
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});
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if (!edges.length) {
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return lines;
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}
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// Start scanning
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let activeEdges = [];
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let y = edges[0].ymin;
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let iteration = 0;
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while (activeEdges.length || edges.length) {
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if (edges.length) {
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let ix = -1;
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for (let i = 0; i < edges.length; i++) {
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if (edges[i].ymin > y) {
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break;
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}
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ix = i;
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}
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const removed = edges.splice(0, ix + 1);
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removed.forEach((edge) => {
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activeEdges.push({ s: y, edge });
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});
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}
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activeEdges = activeEdges.filter((ae) => {
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if (ae.edge.ymax <= y) {
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return false;
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}
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return true;
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});
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activeEdges.sort((ae1, ae2) => {
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if (ae1.edge.x === ae2.edge.x) {
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return 0;
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}
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return (ae1.edge.x - ae2.edge.x) / Math.abs((ae1.edge.x - ae2.edge.x));
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});
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// fill between the edges
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if ((hachureStepOffset !== 1) || (iteration % gap === 0)) {
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if (activeEdges.length > 1) {
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for (let i = 0; i < activeEdges.length; i = i + 2) {
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const nexti = i + 1;
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if (nexti >= activeEdges.length) {
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break;
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}
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const ce = activeEdges[i].edge;
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const ne = activeEdges[nexti].edge;
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lines.push([
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[Math.round(ce.x), y],
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[Math.round(ne.x), y],
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]);
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}
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}
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}
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y += hachureStepOffset;
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activeEdges.forEach((ae) => {
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ae.edge.x = ae.edge.x + (hachureStepOffset * ae.edge.islope);
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});
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iteration++;
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}
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return lines;
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}
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