x

NEWS.md

@@ -17,7 +17,7 @@
 ## new
 `compareGeom` for list and SpatRasterCollection [#1207](https://github.com/rspatial/terra/issues/1207) by Sarah Endicott
 `is.rotated<SpatRaster>` method [#1229](https://github.com/rspatial/terra/issues/1229) by Andy Lyons
-
+`forceCCW<SpatVector>` method to force counter-clockwise orientation [#1249](https://github.com/rspatial/terra/issues/1249) by srfall.
 
 # version 1.7-39
 

R/geom.R

@@ -661,6 +661,6 @@ setMethod("forceCCW", signature(x="SpatVector"),
 	function(x) {
 		x <- deepcopy(x)
 		x@pnt$make_CCW()
-		x
+		messages(x)
 	}
 )

man/forceCCW.Rd

@@ -0,0 +1,33 @@
+\name{forceCCW}
+
+\alias{forceCCW}
+\alias{forceCCW,SpatVector-method}
+
+
+\title{force counter-clockwise polygons}
+
+
+\description{
+Assure that the nodes of outer rings of polygons are in counter-clockwise order.
+}
+
+\usage{
+\S4method{forceCCW}{SpatVector}(x)
+}
+
+\arguments{
+  \item{x}{SpatVector of polygons}
+}
+
+\value{
+SpatVector
+}
+
+\examples{
+p <- vect("POLYGON ((2 45, 2 55, 18 55, 18 45, 2 45))")
+pcc <- forceCCW(p)
+geom(pcc, wkt=TRUE)
+}
+
+\keyword{spatial}
+

src/geos_methods.cpp

@@ -3218,3 +3218,30 @@ bool SpatPart::is_CCW() {
 	}
 #endif
 }
+
+
+
+void SpatVector::make_CCW() {
+	#ifndef GEOS370
+		setError("GEOS >= 3.7 needed for CCW");
+		return;
+	#else
+	size_t n = size();
+	if (n == 0) return;
+	if (geoms[0].gtype != polygons) return;
+	for (size_t i=0; i<n; i++) {
+		for (size_t j=0; j<geoms[i].parts.size(); j++) {
+			if (!geoms[i].parts[j].is_CCW()) {
+				std::reverse(geoms[i].parts[j].x.begin(), geoms[i].parts[j].x.end());
+				std::reverse(geoms[i].parts[j].y.begin(), geoms[i].parts[j].y.end());
+				for (size_t k=0; k<geoms[i].parts[j].nHoles(); k++) {
+					std::reverse(geoms[i].parts[j].holes[k].x.begin(), geoms[i].parts[j].holes[k].x.end());
+					std::reverse(geoms[i].parts[j].holes[k].y.begin(), geoms[i].parts[j].holes[k].y.end());
+				}
+			}
+		}
+	}
+	#endif
+}
+
+

src/spatVector.cpp

@@ -1433,22 +1433,3 @@ std::vector<std::vector<std::vector<std::vector<double>>>> SpatVector::polygonsL
 
 
 
-void SpatVector::make_CCW() {
-	size_t n = size();
-	if (n == 0) return;
-	if (geoms[0].gtype != polygons) return;
-	for (size_t i=0; i<n; i++) {
-		for (size_t j=0; j<geoms[i].parts.size(); j++) {
-			if (!geoms[i].parts[j].is_CCW()) {
-				std::reverse(geoms[i].parts[j].x.begin(), geoms[i].parts[j].x.end());
-				std::reverse(geoms[i].parts[j].y.begin(), geoms[i].parts[j].y.end());
-				for (size_t k=0; k<geoms[i].parts[j].nHoles(); k++) {
-					std::reverse(geoms[i].parts[j].holes[k].x.begin(), geoms[i].parts[j].holes[k].x.end());
-					std::reverse(geoms[i].parts[j].holes[k].y.begin(), geoms[i].parts[j].holes[k].y.end());
-				}
-			}
-		}
-	}
-}
-
-