geohash_point_as_int()

unsigned int geohash_point_as_int

(

POINT2D *

pt

)

Definition at line 672 of file lwalgorithm.c.

{
        int is_even=1;
        double lat[2], lon[2], mid;
        int bit=32;
        unsigned int ch = 0;
 
        double longitude = pt->x;
        double latitude = pt->y;
 
        lat[0] = -90.0;
        lat[1] = 90.0;
        lon[0] = -180.0;
        lon[1] = 180.0;
 
        while (--bit >= 0)
        {
                if (is_even)
                {
                        mid = (lon[0] + lon[1]) / 2;
                        if (longitude > mid)
                        {
                                ch |= 0x0001u << bit;
                                lon[0] = mid;
                        }
                        else
                        {
                                lon[1] = mid;
                        }
                }
                else
                {
                        mid = (lat[0] + lat[1]) / 2;
                        if (latitude > mid)
                        {
                                ch |= 0x0001 << bit;
                                lat[0] = mid;
                        }
                        else
                        {
                                lat[1] = mid;
                        }
                }
 
                is_even = !is_even;
        }
        return ch;
}

References POINT2D::x, and POINT2D::y.

Referenced by circ_node_compare(), and test_geohash_point_as_int().

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