H3Error cellToBBox()

in h3_polyfill.c [221:266]

• 33 lines of code
• 9 McCabe index (conditional complexity)

H3Error cellToBBox(H3Index cell, BBox *out, bool coverChildren) {
    // Adjust the BBox to handle poles, if needed
    int res = H3_GET_RESOLUTION(cell);

    if (res == 0) {
        int baseCell = H3_GET_BASE_CELL(cell);
        if (NEVER(baseCell < 0) || baseCell >= NUM_BASE_CELLS) {
            return E_CELL_INVALID;
        }
        *out = RES0_BBOXES[baseCell];
    } else {
        LatLng center;
        H3Error centerErr = H3_EXPORT(cellToLatLng)(cell, &center);
        if (centerErr != E_SUCCESS) {
            return centerErr;
        }
        double lngRatio = 1 / cos(center.lat);
        out->north = center.lat + MAX_EDGE_LENGTH_RADS[res];
        out->south = center.lat - MAX_EDGE_LENGTH_RADS[res];
        out->east = center.lng + MAX_EDGE_LENGTH_RADS[res] * lngRatio;
        out->west = center.lng - MAX_EDGE_LENGTH_RADS[res] * lngRatio;
    }

    // Buffer the bounding box to cover children. Call this even if no buffering
    // is required in order to normalize the bbox to lat/lng bounds
    scaleBBox(out, coverChildren ? CHILD_SCALE_FACTOR : CELL_SCALE_FACTOR);

    // Cell that contains the north pole
    if (cell == NORTH_POLE_CELLS[res]) {
        out->north = M_PI_2;
    }

    // Cell that contains the south pole
    if (cell == SOUTH_POLE_CELLS[res]) {
        out->south = -M_PI_2;
    }

    // If we contain a pole, expand the longitude to include the full domain,
    // effectively making the bbox a circle around the pole.
    if (out->north == M_PI_2 || out->south == -M_PI_2) {
        out->east = M_PI;
        out->west = -M_PI;
    }

    return E_SUCCESS;
}