lwpoly_grid()

LWPOLY* lwpoly_grid	(	const LWPOLY *	poly,
		const gridspec *	grid
	)

Definition at line 642 of file lwpoly.c.

References LWDEBUGF, lwerror(), lwgeom_has_m(), lwgeom_has_z(), lwpoly_add_ring(), lwpoly_construct_empty(), lwpoly_free(), POINTARRAY::npoints, LWPOLY::nrings, ptarray_free(), ptarray_grid(), LWPOLY::srid, gridspec_t::xsize, and gridspec_t::ysize.

Referenced by lwgeom_grid().

{
        LWPOLY *opoly;
        int ri;

#if 0
        /*
         * TODO: control this assertion
         * it is assumed that, since the grid size will be a pixel,
         * a visible ring should show at least a white pixel inside,
         * thus, for a square, that would be grid_xsize*grid_ysize
         */
        double minvisiblearea = grid->xsize * grid->ysize;
#endif

        LWDEBUGF(3, "lwpoly_grid: applying grid to polygon with %d rings", poly->nrings);

        opoly = lwpoly_construct_empty(poly->srid, lwgeom_has_z((LWGEOM*)poly), lwgeom_has_m((LWGEOM*)poly));

        for (ri=0; ri<poly->nrings; ri++)
        {
                POINTARRAY *ring = poly->rings[ri];
                POINTARRAY *newring;

                newring = ptarray_grid(ring, grid);

                /* Skip ring if not composed by at least 4 pts (3 segments) */
                if ( newring->npoints < 4 )
                {
                        ptarray_free(newring);

                        LWDEBUGF(3, "grid_polygon3d: ring%d skipped ( <4 pts )", ri);

                        if ( ri ) continue;
                        else break; /* this is the external ring, no need to work on holes */
                }

                if ( ! lwpoly_add_ring(opoly, newring) )
                {
                        lwerror("lwpoly_grid, memory error");
                        return NULL;
                }
        }

        LWDEBUGF(3, "lwpoly_grid: simplified polygon with %d rings", opoly->nrings);

        if ( ! opoly->nrings )
        {
                lwpoly_free(opoly);
                return NULL;
        }

        return opoly;
}

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