Javadoc

modules/core/src/main/java/org/locationtech/jts/algorithm/ConvexHull.java

@@ -144,19 +144,21 @@ private static Coordinate[] extractUnique(Coordinate[] pts) {
 
  /**
  * Extracts unique coordinates from an array of coordinates, 
- * up to a maximum count of values.
+ * up to an (optional) maximum count of values.
  * If more than the given maximum of unique values are found,
  * this is reported by returning <code>null</code>.
- * (the expectation is that the original array can then be used).
+ * This avoids scanning all input points if not needed.
+ * If the maximum points is not specified, all unique points are extracted.
  * 
  * @param pts an array of Coordinates
- * @param maxPts the maximum number of unique points to scan
+ * @param maxPts the maximum number of unique points to scan, or -1
  * @return an array of unique values, or null
  */
  private static Coordinate[] extractUnique(Coordinate[] pts, int maxPts) {
  Set<Coordinate> uniquePts = new HashSet<Coordinate>();
  for (Coordinate pt : pts) {
  uniquePts.add(pt);
+ //-- if maxPts is provided, exit if more unique pts found
  if (maxPts >= 0 && uniquePts.size() > maxPts) return null;
  }
  return CoordinateArrays.toCoordinateArray(uniquePts);
@@ -403,10 +405,11 @@ private Geometry lineOrPolygon(Coordinate[] coordinates) {
  }
 
  /**
- *@param vertices the vertices of a linear ring, which may or may not be
+ * Cleans a list of points by removing interior collinear vertices.
+ * 
+ * @param vertices the vertices of a linear ring, which may or may not be
  * flattened (i.e. vertices collinear)
- *@return the coordinates with unnecessary (collinear) vertices
- * removed
+ * @return the coordinates with unnecessary (collinear) vertices removed
  */
  private Coordinate[] cleanRing(Coordinate[] original) {
  Assert.equals(original[0], original[original.length - 1]);