@thi.ng/geom-poly-utils/bounds.js

2D polygon/polyline analysis & processing utilities

import { max3id } from "@thi.ng/math/interval";
import { addmN2, addmN3 } from "@thi.ng/vectors/addmn";
import { addW2 } from "@thi.ng/vectors/addw";
import {
  MAX2,
  MIN2
} from "@thi.ng/vectors/api";
import { distSq2, distSq3 } from "@thi.ng/vectors/distsq";
import { max } from "@thi.ng/vectors/max";
import { min } from "@thi.ng/vectors/min";
import { mulN2, mulN3 } from "@thi.ng/vectors/muln";
const bounds = (points, vmin, vmax, start = 0, end = points.length) => {
  for (let i = start; i < end; i++) {
    const p = points[i];
    min(null, vmin, p);
    max(null, vmax, p);
  }
  return [vmin, vmax];
};
const bounds2 = (points, start = 0, end = points.length) => {
  let minX = Infinity, minY = Infinity, maxX = -Infinity, maxY = -Infinity;
  for (let i = start; i < end; i++) {
    const [x, y] = points[i];
    if (x < minX) minX = x;
    if (x > maxX) maxX = x;
    if (y < minY) minY = y;
    if (y > maxY) maxY = y;
  }
  return [
    [minX, minY],
    [maxX, maxY]
  ];
};
const bounds3 = (points, start = 0, end = points.length) => {
  let minX = Infinity, minY = Infinity, minZ = Infinity, maxX = -Infinity, maxY = -Infinity, maxZ = -Infinity;
  for (let i = start; i < end; i++) {
    const [x, y, z] = points[i];
    if (x < minX) minX = x;
    if (x > maxX) maxX = x;
    if (y < minY) minY = y;
    if (y > maxY) maxY = y;
    if (z < minZ) minZ = z;
    if (z > maxZ) maxZ = z;
  }
  return [
    [minX, minY, minZ],
    [maxX, maxY, maxZ]
  ];
};
const boundingCircle = (pts) => {
  let xmin = MAX2;
  let xmax = MIN2;
  let ymin = MAX2;
  let ymax = MIN2;
  for (let i = pts.length; i-- > 0; ) {
    const p = pts[i];
    if (p[0] < xmin[0]) xmin = p;
    else if (p[0] > xmax[0]) xmax = p;
    if (p[1] < ymin[1]) ymin = p;
    else if (p[1] > ymax[1]) ymax = p;
  }
  const xspan = distSq2(xmin, xmax);
  const yspan = distSq2(ymin, ymax);
  const span = xspan > yspan ? [xmin, xmax] : [ymin, ymax];
  let centroid = addmN2([], ...span, 0.5);
  let rsq = distSq2(centroid, span[0]);
  let r = Math.sqrt(rsq);
  for (let i = pts.length; i-- > 0; ) {
    const p = pts[i];
    const dsq = distSq2(centroid, p);
    if (dsq > rsq) {
      const d = Math.sqrt(dsq);
      r = (r + d) / 2;
      rsq = r * r;
      mulN2(null, addW2(null, centroid, p, r, d - r), 1 / d);
    }
  }
  return [centroid, r];
};
const boundingSphere = (pts) => {
  let xmin = MAX2;
  let xmax = MIN2;
  let ymin = MAX2;
  let ymax = MIN2;
  let zmin = MAX2;
  let zmax = MIN2;
  for (let i = pts.length; i-- > 0; ) {
    const p = pts[i];
    if (p[0] < xmin[0]) xmin = p;
    else if (p[0] > xmax[0]) xmax = p;
    if (p[1] < ymin[1]) ymin = p;
    else if (p[1] > ymax[1]) ymax = p;
    if (p[2] < zmin[1]) zmin = p;
    else if (p[2] > zmax[1]) zmax = p;
  }
  const span = [
    [xmin, xmax],
    [ymin, ymax],
    [zmin, zmax]
  ][max3id(distSq3(xmin, xmax), distSq3(ymin, ymax), distSq3(zmin, zmax))];
  let centroid = addmN3([], ...span, 0.5);
  let rsq = distSq3(centroid, span[0]);
  let r = Math.sqrt(rsq);
  for (let i = pts.length; i-- > 0; ) {
    const p = pts[i];
    const dsq = distSq3(centroid, p);
    if (dsq > rsq) {
      const d = Math.sqrt(dsq);
      r = (r + d) / 2;
      rsq = r * r;
      mulN3(null, addW2(null, centroid, p, r, d - r), 1 / d);
    }
  }
  return [centroid, r];
};
export {
  boundingCircle,
  boundingSphere,
  bounds,
  bounds2,
  bounds3
};