@giro3d/giro3d/utils/ProjUtils.js

A JS/WebGL framework for 3D geospatial data visualization

import proj from 'proj4';
import { MathUtils, Vector2 } from 'three';
import { getConverter } from '../core/geographic/ProjectionCache';

// @ts-expect-error no types
import parseCode from 'proj4/lib/parseCode';
const ZERO = new Vector2(0, 0);

/**
 * Transform the position buffer in place, from the source to the destination CRS.
 * The buffer is expected to contain N * stride elements, where N is the number of points.
 * Only the 2 first elements of each point (i.e the X and Y coordinate) are transformed. The other
 * elements are left untouched.
 *
 * @param buf - The buffer to transform.
 * @param params - The transformation parameters.
 */
function transformBufferInPlace(buf, params) {
  if (params.srcCrs === params.dstCrs) {
    return;
  }
  if (params.stride === undefined || params.stride < 2) {
    throw new Error('invalid stride: must be at least 2');
  }
  const src = proj.Proj(params.srcCrs);
  const dst = proj.Proj(params.dstCrs);
  const tmp = {
    x: 0,
    y: 0
  };
  const length = buf.length;
  const stride = params.stride;
  const offset = params.offset ?? ZERO;
  for (let i = 0; i < length; i += stride) {
    tmp.x = buf[i + 0];
    tmp.y = buf[i + 1];
    const out = proj.transform(src, dst, tmp);
    buf[i + 0] = out.x + offset.x;
    buf[i + 1] = out.y + offset.y;
  }
}

/**
 * Transforms the vector array _in place_, from the source to the destination CRS.
 */
function transformVectors(srcCrs, dstCrs, points) {
  const converter = getConverter(srcCrs, dstCrs);

  // The mercator projection does not work at poles

  for (let i = 0; i < points.length; i++) {
    const pt0 = points[i];
    if (srcCrs === 'EPSG:4326' && dstCrs === 'EPSG:3857') {
      pt0.setY(MathUtils.clamp(pt0.y, -89.999999, 89.999999));
    }
    const pt1 = converter.forward(pt0);
    // @ts-expect-error weird error
    points[i].copy(pt1);
  }
}
function getCode(authority) {
  const [auth, code] = Object.entries(authority)[0];
  return `${auth}:${code}`;
}
function getWKTCrsCode(wkt) {
  const parsed = parseCode(wkt);
  if ('ID' in parsed) {
    // WKT 2 / PROJCRS
    return getCode(parsed.ID);
  } else if ('PROJCS' in parsed) {
    // WKT 1 / COMPD_CS
    return getCode(parsed['PROJCS'].AUTHORITY);
  } else if ('AUTHORITY' in parsed) {
    // WKT 1 / PROJCS
    return getCode(parsed.AUTHORITY);
  }
  return undefined;
}
export default {
  transformBufferInPlace,
  transformVectors,
  getWKTCrsCode
};