SEXP rgeos_simplify(SEXP env, SEXP obj, SEXP tol, SEXP id, SEXP byid, SEXP topPres) {
GEOSContextHandle_t GEOShandle = getContextHandle(env);
SEXP p4s = GET_SLOT(obj, install("proj4string"));
GEOSGeom geom = rgeos_convert_R2geos(env, obj);
int type = GEOSGeomTypeId_r(GEOShandle, geom);
int preserve = LOGICAL_POINTER(topPres)[0];
double tolerance = NUMERIC_POINTER(tol)[0];
int n = 1;
if (LOGICAL_POINTER(byid)[0] && type == GEOS_GEOMETRYCOLLECTION)
n = GEOSGetNumGeometries_r(GEOShandle, geom);
if (n < 1) error("rgeos_simplify: invalid number of geometries");
GEOSGeom *resgeoms = (GEOSGeom *) R_alloc((size_t) n, sizeof(GEOSGeom));
for(int i=0; i<n; i++) {
const GEOSGeometry *curgeom = (n > 1) ? (GEOSGeom) GEOSGetGeometryN_r(GEOShandle, geom, i)
: geom;
if (curgeom == NULL)
error("rgeos_topologyfunc: unable to get subgeometries");
resgeoms[i] = (preserve)
? GEOSTopologyPreserveSimplify_r(GEOShandle, curgeom, tolerance)
: GEOSSimplify_r(GEOShandle, curgeom, tolerance);
}
GEOSGeom_destroy_r(GEOShandle, geom);
GEOSGeom res = (n == 1) ? resgeoms[0] :
GEOSGeom_createCollection_r(GEOShandle, GEOS_GEOMETRYCOLLECTION, resgeoms, (unsigned int) n);
return( rgeos_convert_geos2R(env, res, p4s, id) );
}
Polygon Polygon::simplify(double distance_tolerance,
double area_tolerance) const
{
GEOSGeometry *smoothed =
GEOSTopologyPreserveSimplify_r(m_ctx, m_geom, distance_tolerance);
if (!smoothed)
throw pdal_error("Unable to simplify input geometry!");
std::vector<GEOSGeometry*> geometries;
int numGeom = GEOSGetNumGeometries_r(m_ctx, smoothed);
for (int n = 0; n < numGeom; ++n)
{
const GEOSGeometry* m = GEOSGetGeometryN_r(m_ctx, smoothed, n);
if (!m)
throw pdal::pdal_error("Unable to Get GeometryN");
const GEOSGeometry* ering = GEOSGetExteriorRing_r(m_ctx, m);
if (!ering)
throw pdal::pdal_error("Unable to Get Exterior Ring");
GEOSGeometry* exterior = GEOSGeom_clone_r(m_ctx,
GEOSGetExteriorRing_r(m_ctx, m));
if (!exterior)
throw pdal::pdal_error("Unable to clone exterior ring!");
std::vector<GEOSGeometry*> keep_rings;
int numRings = GEOSGetNumInteriorRings_r(m_ctx, m);
for (int i = 0; i < numRings; ++i)
{
double area(0.0);
const GEOSGeometry* iring =
GEOSGetInteriorRingN_r(m_ctx, m, i);
if (!iring)
throw pdal::pdal_error("Unable to Get Interior Ring");
GEOSGeometry* cring = GEOSGeom_clone_r(m_ctx, iring);
if (!cring)
throw pdal::pdal_error("Unable to clone interior ring!");
GEOSGeometry* aring = GEOSGeom_createPolygon_r(m_ctx, cring,
NULL, 0);
int errored = GEOSArea_r(m_ctx, aring, &area);
if (errored == 0)
throw pdal::pdal_error("Unable to get area of ring!");
if (area > area_tolerance)
{
keep_rings.push_back(cring);
}
}
GEOSGeometry* p = GEOSGeom_createPolygon_r(m_ctx, exterior,
keep_rings.data(), keep_rings.size());
if (p == NULL) throw
pdal::pdal_error("smooth polygon could not be created!" );
geometries.push_back(p);
}
GEOSGeometry* o = GEOSGeom_createCollection_r(m_ctx, GEOS_MULTIPOLYGON,
geometries.data(), geometries.size());
Polygon p(o, m_srs, m_ctx);
GEOSGeom_destroy_r(m_ctx, smoothed);
GEOSGeom_destroy_r(m_ctx, o);
return p;
}
