gbox_angular_height()

double gbox_angular_height

(

const GBOX *

gbox

)

Returns the angular height (latitudinal span) of the box in radians.

GBOX utility functions to figure out coverage/location on the globe.

Definition at line 188 of file lwgeodetic.c.

{
        double d[6];
        int i;
        double zmin = FLT_MAX;
        double zmax = -1 * FLT_MAX;
        POINT3D pt;
 
        /* Take a copy of the box corners so we can treat them as a list */
        /* Elements are xmin, xmax, ymin, ymax, zmin, zmax */
        memcpy(d, &(gbox->xmin), 6*sizeof(double));
 
        /* Generate all 8 corner vectors of the box */
        for ( i = 0; i < 8; i++ )
        {
                pt.x = d[i / 4];
                pt.y = d[2 + (i % 4) / 2];
                pt.z = d[4 + (i % 2)];
                normalize(&pt);
                if ( pt.z < zmin ) zmin = pt.z;
                if ( pt.z > zmax ) zmax = pt.z;
        }
        return asin(zmax) - asin(zmin);
}

References normalize(), POINT3D::x, GBOX::xmin, POINT3D::y, and POINT3D::z.

Referenced by geography_bestsrid(), and test_gbox_utils().

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