h3ToGeo

Functions
EXTENSION_NOINLINE int64_t H3_EXPORT()	h3ToGeoPacked (H3Index h3)
	find the lat/lon center point g of the cell h3 More...
EXTENSION_NOINLINE double H3_EXPORT()	h3ToLon (H3Index h3)
EXTENSION_NOINLINE double H3_EXPORT()	h3ToLat (H3Index h3)

Detailed Description

Functions for h3ToGeo

Function Documentation

EXTENSION_NOINLINE int64_t H3_EXPORT() h3ToGeoPacked

(

H3Index

h3

)

find the lat/lon center point g of the cell h3

Determines the WGS84 lat/lon coordinates of the center point of an H3 index packed into a 9.22 fixed-point value. This allows 6 decimal places of precision, which equates to a maximum error of 111.32 millimeters at the equator.

To unpack: lon = ((packed_int & 0xffffffff) / 1000000.0) - 180.0 lat = ((packed_int >> 32) / 1000000.0) - 90.0

Parameters

h3	The H3 index.

Returns

64-bit int packed with the lat/lon coordinates

Definition at line 853 of file h3Index.hpp.

References _h3ToGeo(), GeoCoord, LAT_INDEX, LON_INDEX, and radsToDegs().

                                                                {
  GeoCoord(g);
  _h3ToGeo(h3, g);

  // and pack as two 9.22 fixed-point values into 64-bits. Going to preserve 6 decimal
  // places (hence the 1000000.0 magic number). Lon range will be 0-360 and lat 0-180 in
  // order to keep the cast to int64_t positive for easier packing. We could add extra
  // precision if we use a uint64_t, but unfortunately uint64_t is an unsupported type
  // thru calcite. The +0.5 is for rounding.
  int64_t decimal_lon =
      static_cast<int64_t>((radsToDegs(g[LON_INDEX]) + 180.0f) * 1000000.0 + 0.5);
  int64_t decimal_lat =
      static_cast<int64_t>((radsToDegs(g[LAT_INDEX]) + 90.f) * 1000000.0 + 0.5);
  return (decimal_lon & 0xFFFFFFFF) | ((decimal_lat & 0XFFFFFFFF) << 32);
}

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EXTENSION_NOINLINE double H3_EXPORT() h3ToLat

(

H3Index

h3

)

Determines the WGS84 longitude coordinate of the center point of an H3 index.

Parameters

h3	The H3 index.

Returns

WGS84 latitude in double precision

Definition at line 887 of file h3Index.hpp.

References _h3ToGeo(), GeoCoord, LAT_INDEX, and radsToDegs().

                                                         {
  GeoCoord(g);
  _h3ToGeo(h3, g);
  return radsToDegs(g[LAT_INDEX]);
}

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EXTENSION_NOINLINE double H3_EXPORT() h3ToLon

(

H3Index

h3

)

Determines the WGS84 longitude coordinate of the center point of an H3 index.

Parameters

h3	The H3 index.

Returns

WGS84 longitude in double precision

Definition at line 875 of file h3Index.hpp.

References _h3ToGeo(), GeoCoord, LON_INDEX, and radsToDegs().

                                                         {
  GeoCoord(g);
  _h3ToGeo(h3, g);
  return radsToDegs(g[LON_INDEX]);
}

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