All files S2Cell.ts

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import Long = require('long');
import {Decimal} from './decimal';
import {S2CellId} from "./S2CellId";
import {S2Point} from "./S2Point";
import {S2LatLng} from "./S2LatLng";
import {S2Projections} from "./S2Projections";
import {R2Vector} from "./R2Vector";
import {MutableInteger} from "./MutableInteger";
import {S2} from "./S2";
import {S2LatLngRect} from "./S2LatLngRect";
import {R1Interval} from "./R1Interval";
import {S1Interval} from "./S1Interval";
import {S2Cap} from "./S2Cap";
export class S2Cell {
  private static MAX_CELL_SIZE = 1 << S2CellId.MAX_LEVEL;
 
  private _face:number;
  private _level:number;
  private _orientation:number;
  private _uv:decimal.Decimal[][];
 
  constructor(private cellID:S2CellId) {
    this._uv = [];
    this._uv.push([]);
    this._uv.push([]);
    this.init(cellID)
  }
 
  get id():S2CellId {
    return this.cellID;
  }
 
  get face():number {
    return this._face;
  }
 
  get level():number {
    return this._level;
  }
 
  get orientation():number {
    return this._orientation;
  }
 
 
 
// This is a static method in order to provide named parameters.
  public static fromFacePosLevel(face:number, pos:number, level:number):S2Cell {
    return new S2Cell(S2CellId.fromFacePosLevel(face, new Long(pos), level));
  }
 
// Convenience methods.
  public static fromPoint(p:S2Point):S2Cell {
    return new S2Cell(S2CellId.fromPoint(p))
  }
 
  public static fromLatLng(ll:S2LatLng):S2Cell {
    return new S2Cell(S2CellId.fromPoint(ll.toPoint()));
  }
 
 
  public isLeaf():boolean {
    return this.level == S2CellId.MAX_LEVEL;
  }
 
  public getVertex(k:number):S2Point {
    return S2Point.normalize(this.getVertexRaw(k));
  }
 
  /**
   * Return the k-th vertex of the cell (k = 0,1,2,3). Vertices are returned in
   * CCW order. The points returned by GetVertexRaw are not necessarily unit
   * length.
   */
  public getVertexRaw(k:number):S2Point {
    // Vertices are returned in the order SW, SE, NE, NW.
 
    return new R2Vector(this._uv[0][(k >> 1) ^ (k & 1)], this._uv[1][k >> 1])
        .toPoint(this.face);
    // return S2Projections.faceUvToXyz(this.face, );
  }
 
  public getEdge(k:number):S2Point {
    return S2Point.normalize(this.getEdgeRaw(k));
  }
 
  public getEdgeRaw(k:number):S2Point {
    switch (k) {
      case 0:
        return S2Projections.getVNorm(this.face, this._uv[1][0]); // South
      case 1:
        return S2Projections.getUNorm(this.face, this._uv[0][1]); // East
      case 2:
        return S2Point.neg(S2Projections.getVNorm(this.face, this._uv[1][1])); // North
      default:
        return S2Point.neg(S2Projections.getUNorm(this.face, this._uv[0][0])); // West
    }
  }
 
 
  /**
   * Return the inward-facing normal of the great circle passing through the
   * edge from vertex k to vertex k+1 (mod 4). The normals returned by
   * GetEdgeRaw are not necessarily unit length.
   *
   *  If this is not a leaf cell, set children[0..3] to the four children of
   * this cell (in traversal order) and return true. Otherwise returns false.
   * This method is equivalent to the following:
   *
   *  for (pos=0, id=child_begin(); id != child_end(); id = id.next(), ++pos)
   * children[i] = S2Cell(id);
   *
   * except that it is more than two times faster.
   */
  public subdivide():S2Cell[] {
    // This function is equivalent to just iterating over the child cell ids
    // and calling the S2Cell constructor, but it is about 2.5 times faster.
 
    if (this.isLeaf()) {
      return null;
    }
 
    // Compute the cell midpoint in uv-space.
    // const uvMid = this.getCenterUV();
    const children:S2Cell[] = new Array(4);
    // Create four children with the appropriate bounds.
    let id = this.cellID.childBegin();
    for (let pos = 0; pos < 4; ++pos, id = id.next()) {
      children[pos] = new S2Cell(id);
      // S2Cell child = children[pos];
      // child.face = this.face;
      // child.level = (byte) (this.level + 1);
      // child.orientation = (byte) (this.orientation ^ S2.posToOrientation(pos));
      // child.cellId = id;
      // int ij = S2.posToIJ(this.orientation, pos);
      // for (let d = 0; d < 2; ++d) {
      //   // The dimension 0 index (i/u) is in bit 1 of ij.
      //   int m = 1 - ((ij >> (1 - d)) & 1);
      //   child._uv[d][m] = uvMid.get(d);
      //   child._uv[d][1 - m] = this._uv[d][1 - m];
      // }
    }
    return children;
  }
 
  /**
   * Return the direction vector corresponding to the center in (s,t)-space of
   * the given cell. This is the point at which the cell is divided into four
   * subcells; it is not necessarily the centroid of the cell in (u,v)-space or
   * (x,y,z)-space. The point returned by GetCenterRaw is not necessarily unit
   * length.
   */
  public getCenter():S2Point {
    return S2Point.normalize(this.getCenterRaw());
  }
 
  public getCenterRaw():S2Point {
    return this.cellID.toPointRaw();
  }
 
  /**
   * Return the center of the cell in (u,v) coordinates (see {@code
   * S2Projections}). Note that the center of the cell is defined as the point
   * at which it is recursively subdivided into four children; in general, it is
   * not at the midpoint of the (u,v) rectangle covered by the cell
   */
  public getCenterUV():R2Vector {
    const i = new MutableInteger(0);
    const j = new MutableInteger(0);
    this.cellID.toFaceIJOrientation(i, j, null);
    let cellSize = 1 << (S2CellId.MAX_LEVEL - this.level);
 
    // TODO(dbeaumont): Figure out a better naming of the variables here (and elsewhere).
    let si = (i.val & -cellSize) * 2 + cellSize - S2Cell.MAX_CELL_SIZE;
    let x = R2Vector.singleStTOUV(S2.toDecimal(1).dividedBy(S2Cell.MAX_CELL_SIZE).times(si))
    // let x = S2Projections.stToUV((1.0 / S2Cell.MAX_CELL_SIZE) * si);
 
    let sj = (j.val & -cellSize) * 2 + cellSize - S2Cell.MAX_CELL_SIZE;
    let y = R2Vector.singleStTOUV(S2.toDecimal(1).dividedBy(S2Cell.MAX_CELL_SIZE).times(sj))
    // double y = S2Projections.stToUV((1.0 / S2Cell.MAX_CELL_SIZE) * sj);
 
    return new R2Vector(x, y);
  }
 
  /**
   * Return the average area of cells at this level. This is accurate to within
   * a factor of 1.7 (for S2_QUADRATIC_PROJECTION) and is extremely cheap to
   * compute.
   */
  public static averageArea(level):number {
    return S2Projections.AVG_AREA.getValue(level);
  }
 
  /**
   * Return the average area of cells at this level. This is accurate to within
   * a factor of 1.7 (for S2_QUADRATIC_PROJECTION) and is extremely cheap to
   * compute.
   */
  public averageArea():number {
    return S2Projections.AVG_AREA.getValue(this.level);
  }
 
  /**
   * Return the approximate area of this cell. This method is accurate to within
   * 3% percent for all cell sizes and accurate to within 0.1% for cells at
   * level 5 or higher (i.e. 300km square or smaller). It is moderately cheap to
   * compute.
   */
  public  approxArea():number {
 
    // All cells at the first two levels have the same area.
    if (this.level < 2) {
      return this.averageArea();
    }
 
    // First, compute the approximate area of the cell when projected
    // perpendicular to its normal. The cross product of its diagonals gives
    // the normal, and the length of the normal is twice the projected area.
    let flatArea = S2Point.crossProd(
        S2Point.sub(this.getVertex(2), this.getVertex(0)),
        S2Point.sub(this.getVertex(3), this.getVertex(1))
    ).norm().times(0.5);
    // double flatArea = 0.5 * S2Point.crossProd(
    //         S2Point.sub(getVertex(2), getVertex(0)), S2Point.sub(getVertex(3), getVertex(1))).norm();
 
    // Now, compensate for the curvature of the cell surface by pretending
    // that the cell is shaped like a spherical cap. The ratio of the
    // area of a spherical cap to the area of its projected disc turns out
    // to be 2 / (1 + sqrt(1 - r*r)) where "r" is the radius of the disc.
    // For example, when r=0 the ratio is 1, and when r=1 the ratio is 2.
    // Here we set Pi*r*r == flat_area to find the equivalent disc.
    return flatArea
        .times(2)
        .dividedBy(
            Decimal.min(
                flatArea.times(S2.M_1_PI),
                1
            )
                .neg()
                .plus(1)
                .sqrt()
                .plus(1)
        ).toNumber();
  }
 
//
// /**
//  * Return the area of this cell as accurately as possible. This method is more
//  * expensive but it is accurate to 6 digits of precision even for leaf cells
//  * (whose area is approximately 1e-18).
//  */
  public exactArea():decimal.Decimal {
    const v0 = this.getVertex(0);
    const v1 = this.getVertex(1);
    const v2 = this.getVertex(2);
    const v3 = this.getVertex(3);
    return S2.area(v0, v1, v2).plus(S2.area(v0, v2, v3));
  }
 
// //////////////////////////////////////////////////////////////////////
// S2Region interface (see {@code S2Region} for details):
 
 
  public getCapBound():S2Cap {
    // Use the cell center in (u,v)-space as the cap axis. This vector is
    // very close to GetCenter() and faster to compute. Neither one of these
    // vectors yields the bounding cap with minimal surface area, but they
    // are both pretty close.
    //
    // It's possible to show that the two vertices that are furthest from
    // the (u,v)-origin never determine the maximum cap size (this is a
    // possible future optimization).
    const u = this._uv[0][0].plus(this._uv[0][1]).times(0.5);
    const v = this._uv[1][0].plus(this._uv[1][1]).times(0.5);
 
    let cap = new S2Cap(S2Point.normalize(S2Projections.faceUvToXyz(this.face, u, v)), 0);
    for (let k = 0; k < 4; ++k) {
      cap = cap.addPoint(this.getVertex(k));
    }
    return cap;
  }
 
// We grow the bounds slightly to make sure that the bounding rectangle
// also contains the normalized versions of the vertices. Note that the
// maximum result magnitude is Pi, with a floating-point exponent of 1.
// Therefore adding or subtracting 2**-51 will always change the result.
  private static MAX_ERROR = S2.toDecimal(1.0).dividedBy(S2.toDecimal(new Long(1).shiftLeft(51).toString()));
 
// The 4 cells around the equator extend to +/-45 degrees latitude at the
// midpoints of their top and bottom edges. The two cells covering the
// poles extend down to +/-35.26 degrees at their vertices.
// adding kMaxError (as opposed to the C version) because of asin and atan2
// roundoff errors
  private static POLE_MIN_LAT = Decimal.asin(S2.toDecimal(1.0).dividedBy(3).sqrt()).minus(S2Cell.MAX_ERROR)
// 35.26 degrees
 
 
  public getRectBound():S2LatLngRect {
    Eif (this.level > 0) {
      // Except for cells at level 0, the latitude and longitude extremes are
      // attained at the vertices. Furthermore, the latitude range is
      // determined by one pair of diagonally opposite vertices and the
      // longitude range is determined by the other pair.
      //
      // We first determine which corner (i,j) of the cell has the largest
      // absolute latitude. To maximize latitude, we want to find the point in
      // the cell that has the largest absolute z-coordinate and the smallest
      // absolute x- and y-coordinates. To do this we look at each coordinate
      // (u and v), and determine whether we want to minimize or maximize that
      // coordinate based on the axis direction and the cell's (u,v) quadrant.
      const u = this._uv[0][0].plus(this._uv[0][1]);
      const v = this._uv[1][0].plus(this._uv[1][1]);
      const i = S2Projections.getUAxis(this.face).z.eq(0) ? (u.lt(0) ? 1 : 0) : (u.gt(0) ? 1 : 0);
      const j = S2Projections.getVAxis(this.face).z.eq(0) ? (v.lt(0) ? 1 : 0) : (v.gt(0) ? 1 : 0);
 
      let lat = R1Interval.fromPointPair(this.getLatitude(i, j), this.getLatitude(1 - i, 1 - j));
      lat = lat.expanded(S2Cell.MAX_ERROR).intersection(S2LatLngRect.fullLat());
      Iif (lat.lo.eq(-S2.M_PI_2) || lat.hi .eq(S2.M_PI_2)) {
        return new S2LatLngRect(lat, S1Interval.full());
      }
      let lng = S1Interval.fromPointPair(this.getLongitude(i, 1 - j), this.getLongitude(1 - i, j));
      return new S2LatLngRect(lat, lng.expanded(S2Cell.MAX_ERROR));
    }
 
 
    // The face centers are the +X, +Y, +Z, -X, -Y, -Z axes in that order.
    // assert (S2Projections.getNorm(face).get(face % 3) == ((face < 3) ? 1 : -1));
    switch (this.face) {
      case 0:
        return new S2LatLngRect(
            new R1Interval(-S2.M_PI_4, S2.M_PI_4), new S1Interval(-S2.M_PI_4, S2.M_PI_4));
      case 1:
        return new S2LatLngRect(
            new R1Interval(-S2.M_PI_4, S2.M_PI_4), new S1Interval(S2.M_PI_4, 3 * S2.M_PI_4));
      case 2:
        return new S2LatLngRect(
            new R1Interval(S2Cell.POLE_MIN_LAT, S2.M_PI_2), new S1Interval(-S2.M_PI, S2.M_PI));
      case 3:
        return new S2LatLngRect(
            new R1Interval(-S2.M_PI_4, S2.M_PI_4), new S1Interval(3 * S2.M_PI_4, -3 * S2.M_PI_4));
      case 4:
        return new S2LatLngRect(
            new R1Interval(-S2.M_PI_4, S2.M_PI_4), new S1Interval(-3 * S2.M_PI_4, -S2.M_PI_4));
      default:
        return new S2LatLngRect(
            new R1Interval(-S2.M_PI_2, -S2Cell.POLE_MIN_LAT), new S1Interval(-S2.M_PI, S2.M_PI));
    }
 
  }
 
 
  public mayIntersect(cell:S2Cell):boolean {
    return this.cellID.intersects(cell.cellID);
  }
 
  public contains(p:S2Point):boolean {
    // We can't just call XYZtoFaceUV, because for points that lie on the
    // boundary between two faces (i.e. u or v is +1/-1) we need to return
    // true for both adjacent cells.
 
    const uvPoint = p.toR2Vector(this.face);
    // S2Projections.faceXyzToUv(this.face, p);
    if (uvPoint == null) {
      return false;
    }
    return (uvPoint.x.gte(this._uv[0][0]) && uvPoint.x.lte(this._uv[0][1])
    && uvPoint.y.gte(this._uv[1][0]) && uvPoint.y.lte(this._uv[1][1]));
  }
 
// The point 'p' does not need to be normalized.
 
  public containsC(cell:S2Cell):boolean {
    return this.cellID.contains(cell.cellID);
  }
 
  private init(id:S2CellId) {
    this.cellID = id;
    const ij:MutableInteger[] = [];
    const mOrientation = new MutableInteger(0);
 
    for (let d = 0; d < 2; ++d) {
      ij[d] = new MutableInteger(0);
    }
 
    this._face = id.toFaceIJOrientation(ij[0], ij[1], mOrientation);
    this._orientation = mOrientation.val; // Compress int to a byte.
    this._level = id.level();
    const cellSize = 1 << (S2CellId.MAX_LEVEL - this.level);
    for (let d = 0; d < 2; ++d) {
      // Compute the cell bounds in scaled (i,j) coordinates.
      const sijLo = (ij[d].val & -cellSize) * 2 - S2Cell.MAX_CELL_SIZE;
      const sijHi = sijLo + cellSize * 2;
 
      const s = S2.toDecimal(1).dividedBy(S2Cell.MAX_CELL_SIZE);
      this._uv[d][0] = R2Vector.singleStTOUV(s.times(sijLo))
      //S2Projections.stToUV((1.0 / S2Cell.MAX_CELL_SIZE) * sijLo);
      this._uv[d][1] = R2Vector.singleStTOUV(s.times(sijHi));
      //S2Projections.stToUV((1.0 / S2Cell.MAX_CELL_SIZE) * sijHi);
    }
  }
 
 
// Internal method that does the actual work in the constructors.
 
  private getLatitude(i:number, j:number):decimal.Decimal {
 
    const p = S2Projections.faceUvToXyz(this.face, this._uv[0][i], this._uv[1][j]);
    return Decimal.atan2(
        p.z,
        p.x.pow(2).plus(p.y.pow(2))
            .sqrt()
    );
    // return Math.atan2(p.z, Math.sqrt(p.x * p.x + p.y * p.y));
  }
 
  private getLongitude(i:number, j:number):decimal.Decimal {
    const p = S2Projections.faceUvToXyz(this.face, this._uv[0][i], this._uv[1][j]);
    return Decimal.atan2(
        p.y,
        p.x
    );
    // Math.atan2(p.y, p.x);
  }
 
// Return the latitude or longitude of the cell vertex given by (i,j),
// where "i" and "j" are either 0 or 1.
 
  public  toString():string {
    return "[" + this._face + ", " + this._level + ", " + this._orientation + ", " + this.cellID.toToken() + "]";
  }
 
  public toGEOJSON() {
    const coords = [this.getVertex(0),this.getVertex(1),this.getVertex(2),this.getVertex(3),this.getVertex(0)]
        .map(v => S2LatLng.fromPoint(v))
        .map(v => ([v.lngDegrees.toNumber(), v.latDegrees.toNumber()]))
 
    // const rectJSON = this.getRectBound().toGEOJSON();
    return {
      type: 'Feature',
      geometry: {
        type:'Polygon',
        coordinates: [coords]
      },
      properties: {},
      title: `Cell: ${this.id.toToken()} lvl: ${this.level}`
    };
    // rectJSON.title = `Cell: ${this.id.toToken()}`;
    // return rectJSON;
  }
 
}