lwgeom_simplify_in_place()

int lwgeom_simplify_in_place	(	LWGEOM *	geom,
		double	epsilon,
		int	preserve_collapsed
	)

Definition at line 1737 of file lwgeom.c.

{
        int modified = LW_FALSE;
        switch (geom->type)
        {
                /* No-op! Cannot simplify points or triangles */
                case POINTTYPE:
                        return modified;
                case TRIANGLETYPE:
                {
                        if (preserve_collapsed)
                                return modified;
                        LWTRIANGLE *t = lwgeom_as_lwtriangle(geom);
                        POINTARRAY *pa = t->points;
                        ptarray_simplify_in_place(pa, epsilon, 0);
                        if (pa->npoints < 3)
                        {
                                pa->npoints = 0;
                                modified = LW_TRUE;
                        }
                        break;
                }
                case LINETYPE:
                {
                        LWLINE *g = (LWLINE*)(geom);
                        POINTARRAY *pa = g->points;
                        uint32_t in_npoints = pa->npoints;
                        ptarray_simplify_in_place(pa, epsilon, 2);
                        modified = in_npoints != pa->npoints;
                        /* Invalid output */
                        if (pa->npoints == 1 && pa->maxpoints > 1)
                        {
                                /* Use first point as last point */
                                if (preserve_collapsed)
                                {
                                        pa->npoints = 2;
                                        ptarray_copy_point(pa, 0, 1);
                                }
                                /* Finish the collapse process */
                                else
                                {
                                        pa->npoints = 0;
                                }
                        }
                        /* Duped output, force collapse */
                        if (pa->npoints == 2 && !preserve_collapsed)
                        {
                                if (p2d_same(getPoint2d_cp(pa, 0), getPoint2d_cp(pa, 1)))
                                        pa->npoints = 0;
                        }
                        break;
                }
                case POLYGONTYPE:
                {
                        uint32_t i, j = 0;
                        LWPOLY *g = (LWPOLY*)(geom);
                        for (i = 0; i < g->nrings; i++)
                        {
                                POINTARRAY *pa = g->rings[i];
                                /* Only stop collapse on first ring */
                                int minpoints = (preserve_collapsed && i == 0) ? 4 : 0;
                                /* Skip zero'ed out rings */
                                if(!pa)
                                        continue;
                                uint32_t in_npoints = pa->npoints;
                                ptarray_simplify_in_place(pa, epsilon, minpoints);
                                modified |= in_npoints != pa->npoints;
                                /* Drop collapsed rings */
                                if(pa->npoints < 4)
                                {
                                        if (i == 0)
                                        {
                                                /* If the outter ring is dropped, all can be dropped */
                                                for (i = 0; i < g->nrings; i++)
                                                {
                                                        pa = g->rings[i];
                                                        ptarray_free(pa);
                                                }
                                                break;
                                        }
                                        else
                                        {
                                                /* Drop this inner ring only */
                                                ptarray_free(pa);
                                                continue;
                                        }
                                }
                                g->rings[j++] = pa;
                        }
                        /* Update ring count */
                        g->nrings = j;
                        break;
                }
                /* Can process all multi* types as generic collection */
                case MULTIPOINTTYPE:
                case MULTILINETYPE:
                case MULTIPOLYGONTYPE:
                case TINTYPE:
                case COLLECTIONTYPE:
                {
                        uint32_t i, j = 0;
                        LWCOLLECTION *col = (LWCOLLECTION*)geom;
                        for (i = 0; i < col->ngeoms; i++)
                        {
                                LWGEOM *g = col->geoms[i];
                                if (!g) continue;
                                modified |= lwgeom_simplify_in_place(g, epsilon, preserve_collapsed);
                                /* Drop zero'ed out geometries */
                                if(lwgeom_is_empty(g))
                                {
                                        lwgeom_free(g);
                                        continue;
                                }
                                col->geoms[j++] = g;
                        }
                        /* Update geometry count */
                        col->ngeoms = j;
                        break;
                }
                default:
                {
                        lwerror("%s: unsupported geometry type: %s", __func__, lwtype_name(geom->type));
                        break;
                }
        }
 
        if (modified)
        {
                lwgeom_drop_bbox(geom);
        }
        return modified;
}

References COLLECTIONTYPE, LWCOLLECTION::geoms, getPoint2d_cp(), LINETYPE, LW_FALSE, LW_TRUE, lwerror(), lwgeom_as_lwtriangle(), lwgeom_drop_bbox(), lwgeom_free(), lwgeom_is_empty(), lwgeom_simplify_in_place(), lwtype_name(), POINTARRAY::maxpoints, MULTILINETYPE, MULTIPOINTTYPE, MULTIPOLYGONTYPE, LWCOLLECTION::ngeoms, POINTARRAY::npoints, LWPOLY::nrings, p2d_same(), LWLINE::points, LWTRIANGLE::points, POINTTYPE, POLYGONTYPE, ptarray_copy_point(), ptarray_free(), ptarray_simplify_in_place(), LWPOLY::rings, TINTYPE, TRIANGLETYPE, and LWGEOM::type.

Referenced by lwgeom_simplify(), LWGEOM_simplify2d(), lwgeom_simplify_in_place(), lwgeom_subdivide_recursive(), and mvt_geom().

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