gbox_check_poles()

static int gbox_check_poles ( GBOX *  gbox )

static

Check to see if this geocentric gbox is wrapped around a pole.

Only makes sense if this gbox originated from a polygon, as it's assuming the box is generated from external edges and there's an "interior" which contains the pole.

This function is overdetermined, for very large polygons it might add an unwarranted pole. STILL NEEDS WORK!

Definition at line 316 of file lwgeodetic.c.

{
        int rv = LW_FALSE;
#if POSTGIS_DEBUG_LEVEL >= 4
        char *gbox_str = gbox_to_string(gbox);
        LWDEBUG(4, "checking poles");
        LWDEBUGF(4, "gbox %s", gbox_str);
        lwfree(gbox_str);
#endif
        /* Z axis */
        if (gbox->xmin < 0.0 && gbox->xmax > 0.0 &&
            gbox->ymin < 0.0 && gbox->ymax > 0.0)
        {
                /* Extrema lean positive */
                if ((gbox->zmin > 0.0) && (gbox->zmax > 0.0))
                {
                        LWDEBUG(4, "enclosed positive z axis");
                        gbox->zmax = 1.0;
                }
                /* Extrema lean negative */
                else if ((gbox->zmin < 0.0) && (gbox->zmax < 0.0))
                {
                        LWDEBUG(4, "enclosed negative z axis");
                        gbox->zmin = -1.0;
                }
                /* Extrema both sides! */
                else
                {
                        LWDEBUG(4, "enclosed both z axes");
                        gbox->zmin = -1.0;
                        gbox->zmax = 1.0;
                }
                rv = LW_TRUE;
        }
 
        /* Y axis */
        if (gbox->xmin < 0.0 && gbox->xmax > 0.0 &&
            gbox->zmin < 0.0 && gbox->zmax > 0.0)
        {
                if ((gbox->ymin > 0.0) && (gbox->ymax > 0.0))
                {
                        LWDEBUG(4, "enclosed positive y axis");
                        gbox->ymax = 1.0;
                }
                else if ((gbox->ymin < 0.0) && (gbox->ymax < 0.0))
                {
                        LWDEBUG(4, "enclosed negative y axis");
                        gbox->ymin = -1.0;
                }
                else
                {
                        LWDEBUG(4, "enclosed both y axes");
                        gbox->ymax = 1.0;
                        gbox->ymin = -1.0;
                }
                rv = LW_TRUE;
        }
 
        /* X axis */
        if (gbox->ymin < 0.0 && gbox->ymax > 0.0 &&
            gbox->zmin < 0.0 && gbox->zmax > 0.0)
        {
                if ((gbox->xmin > 0.0) && (gbox->xmax > 0.0))
                {
                        LWDEBUG(4, "enclosed positive x axis");
                        gbox->xmax = 1.0;
                }
                else if ((gbox->xmin < 0.0) && (gbox->xmax < 0.0))
                {
                        LWDEBUG(4, "enclosed negative x axis");
                        gbox->xmin = -1.0;
                }
                else
                {
                        LWDEBUG(4, "enclosed both x axes");
                        gbox->xmax = 1.0;
                        gbox->xmin = -1.0;
                }
 
                rv = LW_TRUE;
        }
 
        return rv;
}

References gbox_to_string(), LW_FALSE, LW_TRUE, LWDEBUG, LWDEBUGF, lwfree(), GBOX::xmax, GBOX::xmin, GBOX::ymax, GBOX::ymin, GBOX::zmax, and GBOX::zmin.

Referenced by lwpolygon_calculate_gbox_geodetic().

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