/**
   * Creates a elliptical arc, as a LineString.
   *
   * @return an elliptical arc
   */
  public LineString createArc(double startAng, double endAng) {
    Envelope env = dim.getEnvelope();
    double xRadius = env.getWidth() / 2.0;
    double yRadius = env.getHeight() / 2.0;

    double centreX = env.getMinX() + xRadius;
    double centreY = env.getMinY() + yRadius;

    double angSize = (endAng - startAng);
    if (angSize <= 0.0 || angSize > 2 * Math.PI) angSize = 2 * Math.PI;
    double angInc = angSize / nPts;

    Coordinate[] pts = new Coordinate[nPts];
    int iPt = 0;
    for (int i = 0; i < nPts; i++) {
      double ang = startAng + i * angInc;
      double x = xRadius * Math.cos(ang) + centreX;
      double y = yRadius * Math.sin(ang) + centreY;
      Coordinate pt = new Coordinate(x, y);
      geomFact.getPrecisionModel().makePrecise(pt);
      pts[iPt++] = pt;
    }
    LineString line = geomFact.createLineString(pts);
    return line;
  }
  /**
   * Creates a rectangular {@link Polygon}.
   *
   * @return a rectangular Polygon
   */
  public Polygon createRectangle() {
    int i;
    int ipt = 0;
    int nSide = nPts / 4;
    if (nSide < 1) nSide = 1;
    double XsegLen = dim.getEnvelope().getWidth() / nSide;
    double YsegLen = dim.getEnvelope().getHeight() / nSide;

    Coordinate[] pts = new Coordinate[4 * nSide + 1];
    Envelope env = dim.getEnvelope();

    double maxx = env.getMinX() + nSide * XsegLen;
    double maxy = env.getMinY() + nSide * XsegLen;

    for (i = 0; i < nSide; i++) {
      double x = env.getMinX() + i * XsegLen;
      double y = env.getMinY();
      pts[ipt++] = new Coordinate(x, y);
    }
    for (i = 0; i < nSide; i++) {
      double x = env.getMaxX();
      double y = env.getMinY() + i * YsegLen;
      pts[ipt++] = new Coordinate(x, y);
    }
    for (i = 0; i < nSide; i++) {
      double x = env.getMaxX() - i * XsegLen;
      double y = env.getMaxY();
      pts[ipt++] = new Coordinate(x, y);
    }
    for (i = 0; i < nSide; i++) {
      double x = env.getMinX();
      double y = env.getMaxY() - i * YsegLen;
      pts[ipt++] = new Coordinate(x, y);
    }
    pts[ipt++] = new Coordinate(pts[0]);

    LinearRing ring = geomFact.createLinearRing(pts);
    Polygon poly = geomFact.createPolygon(ring, null);
    return poly;
  }
  /**
   * Creates a circular {@link Polygon}.
   *
   * @return a circle
   */
  public Polygon createCircle() {

    Envelope env = dim.getEnvelope();
    double xRadius = env.getWidth() / 2.0;
    double yRadius = env.getHeight() / 2.0;

    double centreX = env.getMinX() + xRadius;
    double centreY = env.getMinY() + yRadius;

    Coordinate[] pts = new Coordinate[nPts + 1];
    int iPt = 0;
    for (int i = 0; i < nPts; i++) {
      double ang = i * (2 * Math.PI / nPts);
      double x = xRadius * Math.cos(ang) + centreX;
      double y = yRadius * Math.sin(ang) + centreY;
      Coordinate pt = new Coordinate(x, y);
      pts[iPt++] = pt;
    }
    pts[iPt] = pts[0];

    LinearRing ring = geomFact.createLinearRing(pts);
    Polygon poly = geomFact.createPolygon(ring, null);
    return poly;
  }
 /**
  * Sets the location of the shape by specifying the centre of the shape's bounding box
  *
  * @param centre the centre coordinate of the shape
  */
 public void setCentre(Coordinate centre) {
   dim.setCentre(centre);
 }
 /**
  * Sets the location of the shape by specifying the base coordinate (which in most cases is the
  * lower left point of the envelope containing the shape).
  *
  * @param base the base coordinate of the shape
  */
 public void setBase(Coordinate base) {
   dim.setBase(base);
 }
 /**
  * Sets the height of the shape.
  *
  * @param height the height of the shape
  */
 public void setHeight(double height) {
   dim.setHeight(height);
 }
 /**
  * Sets the width of the shape.
  *
  * @param width the width of the shape
  */
 public void setWidth(double width) {
   dim.setWidth(width);
 }
 /**
  * Sets the size of the extent of the shape in both x and y directions.
  *
  * @param size the size of the shape's extent
  */
 public void setSize(double size) {
   dim.setSize(size);
 }