rt_util_envelope_to_lwpoly()

LWPOLY * rt_util_envelope_to_lwpoly

(

rt_envelope

ext

)

Definition at line 491 of file rt_util.c.

  {
        LWPOLY *npoly = NULL;
        POINTARRAY **rings = NULL;
        POINTARRAY *pts = NULL;
        POINT4D p4d;
 
        rings = (POINTARRAY **) rtalloc(sizeof (POINTARRAY*));
        if (!rings) {
                rterror("rt_util_envelope_to_lwpoly: Out of memory building envelope's geometry");
                return NULL;
        }
        rings[0] = ptarray_construct(0, 0, 5);
        if (!rings[0]) {
                rterror("rt_util_envelope_to_lwpoly: Out of memory building envelope's geometry ring");
                return NULL;
        }
 
        pts = rings[0];
 
        /* Upper-left corner (first and last points) */
        p4d.x = env.MinX;
        p4d.y = env.MaxY;
        ptarray_set_point4d(pts, 0, &p4d);
        ptarray_set_point4d(pts, 4, &p4d);
 
        /* Upper-right corner (we go clockwise) */
        p4d.x = env.MaxX;
        p4d.y = env.MaxY;
        ptarray_set_point4d(pts, 1, &p4d);
 
        /* Lower-right corner */
        p4d.x = env.MaxX;
        p4d.y = env.MinY;
        ptarray_set_point4d(pts, 2, &p4d);
 
        /* Lower-left corner */
        p4d.x = env.MinX;
        p4d.y = env.MinY;
        ptarray_set_point4d(pts, 3, &p4d);
 
        npoly = lwpoly_construct(SRID_UNKNOWN, 0, 1, rings);
        if (npoly == NULL) {
                rterror("rt_util_envelope_to_lwpoly: Could not build envelope's geometry");
                return NULL;
        }
 
        return npoly;
}

References lwpoly_construct(), rt_envelope::MaxX, rt_envelope::MaxY, rt_envelope::MinX, rt_envelope::MinY, ptarray_construct(), ptarray_set_point4d(), rtalloc(), rterror(), SRID_UNKNOWN, POINT4D::x, and POINT4D::y.

Referenced by rt_raster_compute_skewed_raster().

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