// Return closest point to given distance within geometry.
// 'spgeom' must be a LineString
SEXP rgeos_interpolate(SEXP env, SEXP spgeom, SEXP d, SEXP normalized) {
GEOSContextHandle_t GEOShandle = getContextHandle(env);
GEOSGeom geom = rgeos_convert_R2geos(env, spgeom);
GEOSGeom res_geos;
double dist;
int nlines = length(GET_SLOT(spgeom, install("lines")));
if (nlines < 1) {
error("rgeos_project: invalid number of lines");
}
int n = LENGTH(d);
if (n < 1) {
error("rgeos_interpolate: invalid number of requested points");
}
int pc = 0;
SEXP crd;
PROTECT(crd = NEW_NUMERIC(n*2)); pc++;
double x;
double y;
SEXP ans;
// select interpolation function (normalized/unnormalized)
GEOSGeometry GEOS_DLL *(*interp_fun)(GEOSContextHandle_t,
const GEOSGeometry*,
double);
if (LOGICAL_POINTER(normalized)[0]) {
interp_fun = &GEOSInterpolateNormalized_r;
} else {
interp_fun = &GEOSInterpolate_r;
}
// interpolate points and store result in coord matrix
for (int i = 0; i < n; i++) {
dist = NUMERIC_POINTER(d)[i];
res_geos = (*interp_fun)(GEOShandle, geom, dist);
rgeos_Pt2xy(env, res_geos, &x, &y);
NUMERIC_POINTER(crd)[i] = x;
NUMERIC_POINTER(crd)[n+i] = y;
}
GEOSGeom_destroy_r(GEOShandle, geom);
GEOSGeom_destroy_r(GEOShandle, res_geos);
// return coordinates as matrix
PROTECT(ans = rgeos_formatcrdMat(crd, n)); pc++;
UNPROTECT(pc);
return(ans);
}
SEXP rgeos_geosring2Polygon(SEXP env, GEOSGeom lr, int hole) {
GEOSContextHandle_t GEOShandle = getContextHandle(env);
int pc=0;
GEOSCoordSeq s = (GEOSCoordSequence *) GEOSGeom_getCoordSeq_r(GEOShandle, lr);
if (s == NULL)
error("rgeos_geosring2Polygon: CoordSeq failure");
unsigned int n;
if (GEOSCoordSeq_getSize_r(GEOShandle, s, &n) == 0)
error("rgeos_geosring2Polygon: CoordSeq failure");
// Get coordinates
SEXP crd;
PROTECT(crd = rgeos_crdMatFixDir(PROTECT(rgeos_CoordSeq2crdMat(env, s, FALSE, hole)), hole)); pc += 2;
// Calculate area
GEOSGeom p = GEOSGeom_createPolygon_r(GEOShandle,GEOSGeom_clone_r(GEOShandle,lr),NULL,0);
if (p == NULL)
error("rgeos_geosring2Polygon: unable to create polygon");
SEXP area;
PROTECT(area = NEW_NUMERIC(1)); pc++;
NUMERIC_POINTER(area)[0] = 0.0;
if (!GEOSArea_r(GEOShandle, p, NUMERIC_POINTER(area)))
error("rgeos_geosring2Polygon: area calculation failure");
// Calculate label position
SEXP labpt;
PROTECT(labpt = NEW_NUMERIC(2)); pc++;
GEOSGeom centroid = GEOSGetCentroid_r(GEOShandle, p);
double xc, yc;
rgeos_Pt2xy(env, centroid, &xc, &yc);
if (!R_FINITE(xc) || !R_FINITE(yc)) {
xc = 0.0;
yc = 0.0;
for(int i=0; i != n; i++) {
xc += NUMERIC_POINTER(crd)[i];
yc += NUMERIC_POINTER(crd)[(int) (n) +i];
}
xc /= n;
yc /= n;
}
NUMERIC_POINTER(labpt)[0] = xc;
NUMERIC_POINTER(labpt)[1] = yc;
GEOSGeom_destroy_r(GEOShandle, centroid);
GEOSGeom_destroy_r(GEOShandle, p);
// Get ring direction
SEXP ringDir;
PROTECT(ringDir = NEW_INTEGER(1)); pc++;
INTEGER_POINTER(ringDir)[0] = hole ? -1 : 1;
// Get hole status
SEXP Hole;
PROTECT(Hole = NEW_LOGICAL(1)); pc++;
LOGICAL_POINTER(Hole)[0] = hole;
SEXP ans;
PROTECT(ans = NEW_OBJECT(MAKE_CLASS("Polygon"))); pc++;
SET_SLOT(ans, install("ringDir"), ringDir);
SET_SLOT(ans, install("labpt"), labpt);
SET_SLOT(ans, install("area"), area);
SET_SLOT(ans, install("hole"), Hole);
SET_SLOT(ans, install("coords"), crd);
SEXP valid;
PROTECT(valid = SP_PREFIX(Polygon_validate_c)(ans)); pc++;
if (!isLogical(valid)) {
UNPROTECT(pc);
if (isString(valid))
error(CHAR(STRING_ELT(valid, 0)));
else
error("invalid Polygon object");
}
UNPROTECT(pc);
return(ans);
}
