package org.opentrafficsim.road.network.lane;
   
   import java.io.Serializable;
   import java.util.ArrayList;
   import java.util.Arrays;
   import java.util.List;
   
   import javax.media.j3d.Bounds;
   
  import org.djunits.value.vdouble.scalar.Length;
  import org.opentrafficsim.base.Identifiable;
  import org.opentrafficsim.core.geometry.OTSGeometryException;
  import org.opentrafficsim.core.geometry.OTSLine3D;
  import org.opentrafficsim.core.geometry.OTSPoint3D;
  import org.opentrafficsim.core.geometry.OTSShape;
  import org.opentrafficsim.core.network.LateralDirectionality;
  import org.opentrafficsim.core.network.NetworkException;
  
  import nl.tudelft.simulation.dsol.animation.Locatable;
  import nl.tudelft.simulation.dsol.simulators.SimulatorInterface;
  import nl.tudelft.simulation.event.EventProducer;
  import nl.tudelft.simulation.language.Throw;
  import nl.tudelft.simulation.language.d3.DirectedPoint;
  
  /**
   * Cross section elements are used to compose a CrossSectionLink.
   * <p>
   * Copyright (c) 2013-2018 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
   * BSD-style license. See <a href="http://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
   * <p>
   * $LastChangedDate: 2015-09-14 01:33:02 +0200 (Mon, 14 Sep 2015) $, @version $Revision: 1401 $, by $Author: averbraeck $,
   * initial version Aug 19, 2014 <br>
   * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
   * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
   * @author <a href="http://www.citg.tudelft.nl">Guus Tamminga</a>
   */
  public abstract class CrossSectionElement extends EventProducer implements Locatable, Serializable, Identifiable
  {
      /** */
      private static final long serialVersionUID = 20150826L;
  
      /** The id. Should be unique within the parentLink. */
      private final String id;
  
      /** Cross Section Link to which the element belongs. */
      @SuppressWarnings("checkstyle:visibilitymodifier")
      protected final CrossSectionLink parentLink;
  
      /** The offsets and widths at positions along the line, relative to the design line of the parent link. */
      @SuppressWarnings("checkstyle:visibilitymodifier")
      protected final List<CrossSectionSlice> crossSectionSlices;
  
      /** The length of the line. Calculated once at the creation. */
      @SuppressWarnings("checkstyle:visibilitymodifier")
      protected final Length length;
  
      /** The center line of the element. Calculated once at the creation. */
      private final OTSLine3D centerLine;
  
      /** The contour of the element. Calculated once at the creation. */
      private final OTSShape contour;
  
      /**
       * <b>Note:</b> LEFT is seen as a positive lateral direction, RIGHT as a negative lateral direction, with the direction from
       * the StartNode towards the EndNode as the longitudinal direction.
       * @param id String; The id of the CrosssSectionElement. Should be unique within the parentLink.
       * @param parentLink CrossSectionLink; Link to which the element belongs.
       * @param crossSectionSlices List&lt;CrossSectionSlice&gt;; the offsets and widths at positions along the line, relative to
       *            the design line of the parent link. If there is just one with and offset, there should just be one element in
       *            the list with Length = 0. If there are more slices, the last one should be at the length of the design line.
       *            If not, a NetworkException is thrown.
       * @throws OTSGeometryException when creation of the geometry fails
       * @throws NetworkException when id equal to null or not unique, or there are multiple slices and the last slice does not
       *             end at the length of the design line.
       */
      public CrossSectionElement(final CrossSectionLink parentLink, final String id,
              final List<CrossSectionSlice> crossSectionSlices) throws OTSGeometryException, NetworkException
      {
          Throw.when(parentLink == null, NetworkException.class,
                  "Constructor of CrossSectionElement for id %s, parentLink cannot be null", id);
          Throw.when(id == null, NetworkException.class, "Constructor of CrossSectionElement -- id cannot be null");
          for (CrossSectionElement cse : parentLink.getCrossSectionElementList())
          {
              Throw.when(cse.getId().equals(id), NetworkException.class,
                      "Constructor of CrossSectionElement -- id %s not unique within the Link", id);
          }
          this.id = id;
          this.parentLink = parentLink;
  
          this.crossSectionSlices = new ArrayList<>(crossSectionSlices); // copy of list with immutable slices
          Throw.when(this.crossSectionSlices.size() == 0, NetworkException.class,
                  "CrossSectionElement %s is created with zero slices for %s", id, parentLink);
          Throw.when(this.crossSectionSlices.get(0).getRelativeLength().si != 0.0, NetworkException.class,
                  "CrossSectionElement %s for %s has a first slice with relativeLength is not equal to 0.0", id, parentLink);
          Throw.when(
                  this.crossSectionSlices.size() > 1
                          && this.crossSectionSlices.get(this.crossSectionSlices.size() - 1).getRelativeLength()
                                  .ne(this.parentLink.getLength()), NetworkException.class,
                  "CrossSectionElement %s for %s has a last slice with relativeLength is not equal "
                         + "to the length of the parent link", id, parentLink);
 
         if (this.crossSectionSlices.size() <= 2)
         {
             this.centerLine =
                     this.getParentLink().getDesignLine()
                             .offsetLine(getDesignLineOffsetAtBegin().getSI(), getDesignLineOffsetAtEnd().getSI());
         }
         else
         {
             double[] relativeFractions = new double[this.crossSectionSlices.size()];
             double[] offsets = new double[this.crossSectionSlices.size()];
             for (int i = 0; i < this.crossSectionSlices.size(); i++)
             {
                 relativeFractions[i] =
                         this.crossSectionSlices.get(i).getRelativeLength().si / this.parentLink.getLength().si;
                 offsets[i] = this.crossSectionSlices.get(i).getDesignLineOffset().si;
             }
             this.centerLine = this.getParentLink().getDesignLine().offsetLine(relativeFractions, offsets);
         }
 
         this.length = this.centerLine.getLength();
         this.contour = constructContour(this);
 
         this.parentLink.addCrossSectionElement(this);
     }
 
     /**
      * <b>Note:</b> LEFT is seen as a positive lateral direction, RIGHT as a negative lateral direction, with the direction from
      * the StartNode towards the EndNode as the longitudinal direction.
      * @param id String; The id of the CrosssSectionElement. Should be unique within the parentLink.
      * @param parentLink CrossSectionLink; Link to which the element belongs.
      * @param lateralOffsetAtBegin Length; the lateral offset of the design line of the new CrossSectionLink with respect to the
      *            design line of the parent Link at the start of the parent Link
      * @param lateralOffsetAtEnd Length; the lateral offset of the design line of the new CrossSectionLink with respect to the
      *            design line of the parent Link at the end of the parent Link
      * @param beginWidth Length; width at start, positioned <i>symmetrically around</i> the design line
      * @param endWidth Length; width at end, positioned <i>symmetrically around</i> the design line
      * @throws OTSGeometryException when creation of the geometry fails
      * @throws NetworkException when id equal to null or not unique
      */
     public CrossSectionElement(final CrossSectionLink parentLink, final String id, final Length lateralOffsetAtBegin,
             final Length lateralOffsetAtEnd, final Length beginWidth, final Length endWidth) throws OTSGeometryException,
             NetworkException
     {
         this(parentLink, id, fixGradualLateraloffset(parentLink, lateralOffsetAtBegin, lateralOffsetAtEnd, beginWidth,
                 endWidth));
     }
 
     /**
      * Construct a list of cross section slices. using sinusoidal interpolation for changin lateral offset.
      * @param parentLink CrossSectionLink; Link to which the element belongs.
      * @param lateralOffsetAtBegin Length; the lateral offset of the design line of the new CrossSectionLink with respect to the
      *            design line of the parent Link at the start of the parent Link
      * @param lateralOffsetAtEnd Length; the lateral offset of the design line of the new CrossSectionLink with respect to the
      *            design line of the parent Link at the end of the parent Link
      * @param beginWidth Length; width at start, positioned <i>symmetrically around</i> the design line
      * @param endWidth Length; width at end, positioned <i>symmetrically around</i> the design line
      * @return List&ltCrossSectionSlice&gt;; the cross section slices
      */
     private static List<CrossSectionSlice> fixGradualLateraloffset(final CrossSectionLink parentLink,
             final Length lateralOffsetAtBegin, final Length lateralOffsetAtEnd, final Length beginWidth,
             final Length endWidth)
     {
         if ("1021_J23".equals(parentLink.getId()))
         {
             System.out.println("Adding cross section to link " + parentLink.getId());
         }
         List<CrossSectionSlice> result = new ArrayList<>();
         int numPoints = lateralOffsetAtBegin.equals(lateralOffsetAtEnd) ? 2 : 8;
         Length parentLength = parentLink.getLength();
         for (int index = 0; index < numPoints; index++)
         {
             double fraction = index * 1.0 / (numPoints - 1);
             Length lengthAtCrossSection = parentLength.multiplyBy(fraction);
             double relativeOffsetAtFraction = (1 + Math.sin((fraction - 0.5) * Math.PI)) / 2;
             Length offsetAtFraction = Length.interpolate(lateralOffsetAtBegin, lateralOffsetAtEnd, relativeOffsetAtFraction);
             result.add(new CrossSectionSlice(lengthAtCrossSection, offsetAtFraction, Length.interpolate(beginWidth,
                     endWidth, fraction)));
             System.out.println("fraction " + fraction + ", " + result.get(result.size() - 1));
         }
 
         // Arrays.asList(new CrossSectionSlice[] { new CrossSectionSlice(Length.ZERO, lateralOffsetAtBegin, beginWidth),
         // new CrossSectionSlice(parentLink.getLength(), lateralOffsetAtEnd, endWidth) })
         return result;
     }
 
     /**
      * Clone a CrossSectionElement for a new network.
      * @param newCrossSectionLink the new link to which the clone belongs
      * @param newSimulator the new simulator for this network
      * @param animation whether to (re)create animation or not
      * @param cse the element to clone from
      * @throws NetworkException if link already exists in the network, if name of the link is not unique, or if the start node
      *             or the end node of the link are not registered in the network.
      */
     protected CrossSectionElement(final CrossSectionLink newCrossSectionLink, final SimulatorInterface.TimeDoubleUnit newSimulator,
             final boolean animation, final CrossSectionElement cse) throws NetworkException
     {
         this.id = cse.id;
         this.parentLink = newCrossSectionLink;
         this.centerLine = cse.centerLine;
         this.length = this.centerLine.getLength();
         this.contour = cse.contour;
         this.crossSectionSlices = new ArrayList<>(cse.crossSectionSlices);
         newCrossSectionLink.addCrossSectionElement(this);
     }
 
     /**
      * <b>Note:</b> LEFT is seen as a positive lateral direction, RIGHT as a negative lateral direction, with the direction from
      * the StartNode towards the EndNode as the longitudinal direction.
      * @param id String; The id of the CrosssSectionElement. Should be unique within the parentLink.
      * @param parentLink CrossSectionLink; Link to which the element belongs.
      * @param lateralOffset Length; the lateral offset of the design line of the new CrossSectionLink with respect to the design
      *            line of the parent Link
      * @param width Length; width, positioned <i>symmetrically around</i> the design line
      * @throws OTSGeometryException when creation of the geometry fails
      * @throws NetworkException when id equal to null or not unique
      */
     public CrossSectionElement(final CrossSectionLink parentLink, final String id, final Length lateralOffset,
             final Length width) throws OTSGeometryException, NetworkException
     {
         this(parentLink, id, Arrays
                 .asList(new CrossSectionSlice[] { new CrossSectionSlice(Length.ZERO, lateralOffset, width) }));
     }
 
     /**
      * @return parentLink.
      */
     public final CrossSectionLink getParentLink()
     {
         return this.parentLink;
     }
 
     /**
      * Calculate the slice the fractional position is in.
      * @param fractionalPosition the fractional position between 0 and 1 compared to the design line
      * @return int; the lower slice number between 0 and number of slices - 1.
      */
     private int calculateSliceNumber(final double fractionalPosition)
     {
         double linkLength = this.parentLink.getLength().si;
         for (int i = 0; i < this.crossSectionSlices.size() - 1; i++)
         {
             if (fractionalPosition >= this.crossSectionSlices.get(i).getRelativeLength().si / linkLength
                     && fractionalPosition <= this.crossSectionSlices.get(i + 1).getRelativeLength().si / linkLength)
             {
                 return i;
             }
         }
         return this.crossSectionSlices.size() - 2;
     }
 
     /**
      * Retrieve the lateral offset from the Link design line at the specified longitudinal position.
      * @param fractionalPosition double; fractional longitudinal position on this Lane
      * @return Length; the lateralCenterPosition at the specified longitudinal position
      */
     public final Length getLateralCenterPosition(final double fractionalPosition)
     {
         if (this.crossSectionSlices.size() == 1)
         {
             return this.getDesignLineOffsetAtBegin();
         }
         if (this.crossSectionSlices.size() == 2)
         {
             return Length
                     .interpolate(this.getDesignLineOffsetAtBegin(), this.getDesignLineOffsetAtEnd(), fractionalPosition);
         }
         int sliceNr = calculateSliceNumber(fractionalPosition);
         return Length.interpolate(this.crossSectionSlices.get(sliceNr).getDesignLineOffset(),
                 this.crossSectionSlices.get(sliceNr + 1).getDesignLineOffset(), fractionalPosition
                         - this.crossSectionSlices.get(sliceNr).getRelativeLength().si / this.parentLink.getLength().si);
     }
 
     /**
      * Retrieve the lateral offset from the Link design line at the specified longitudinal position.
      * @param longitudinalPosition Length; the longitudinal position on this Lane
      * @return Length; the lateralCenterPosition at the specified longitudinal position
      */
     public final Length getLateralCenterPosition(final Length longitudinalPosition)
     {
         return getLateralCenterPosition(longitudinalPosition.getSI() / getLength().getSI());
     }
 
     /**
      * Return the width of this CrossSectionElement at a specified longitudinal position.
      * @param longitudinalPosition DoubleScalar&lt;LengthUnit&gt;; the longitudinal position
      * @return Length; the width of this CrossSectionElement at the specified longitudinal position.
      */
     public final Length getWidth(final Length longitudinalPosition)
     {
         return getWidth(longitudinalPosition.getSI() / getLength().getSI());
     }
 
     /**
      * Return the width of this CrossSectionElement at a specified fractional longitudinal position.
      * @param fractionalPosition double; the fractional longitudinal position
      * @return Length; the width of this CrossSectionElement at the specified fractional longitudinal position.
      */
     public final Length getWidth(final double fractionalPosition)
     {
         if (this.crossSectionSlices.size() == 1)
         {
             return this.getBeginWidth();
         }
         if (this.crossSectionSlices.size() == 2)
         {
             return Length.interpolate(this.getBeginWidth(), this.getEndWidth(), fractionalPosition);
         }
         int sliceNr = calculateSliceNumber(fractionalPosition);
         return Length.interpolate(this.crossSectionSlices.get(sliceNr).getWidth(), this.crossSectionSlices.get(sliceNr + 1)
                 .getWidth(), fractionalPosition - this.crossSectionSlices.get(sliceNr).getRelativeLength().si
                 / this.parentLink.getLength().si);
     }
 
     /**
      * Return the length of this CrossSectionElement as measured along the design line (which equals the center line).
      * @return Length; the length of this CrossSectionElement
      */
     public final Length getLength()
     {
         return this.length;
     }
 
     /**
      * Retrieve the offset from the design line at the begin of the parent link.
      * @return Length; the offset of this CrossSectionElement at the begin of the parent link
      */
     public final Length getDesignLineOffsetAtBegin()
     {
         return this.crossSectionSlices.get(0).getDesignLineOffset();
     }
 
     /**
      * Retrieve the offset from the design line at the end of the parent link.
      * @return Length; the offset of this CrossSectionElement at the end of the parent link
      */
     public final Length getDesignLineOffsetAtEnd()
     {
         return this.crossSectionSlices.get(this.crossSectionSlices.size() - 1).getDesignLineOffset();
     }
 
     /**
      * Retrieve the width at the begin of the parent link.
      * @return Length; the width of this CrossSectionElement at the begin of the parent link
      */
     public final Length getBeginWidth()
     {
         return this.crossSectionSlices.get(0).getWidth();
     }
 
     /**
      * Retrieve the width at the end of the parent link.
      * @return Length; the width of this CrossSectionElement at the end of the parent link
      */
     public final Length getEndWidth()
     {
         return this.crossSectionSlices.get(this.crossSectionSlices.size() - 1).getWidth();
     }
 
     /**
      * Retrieve the Z offset (used to determine what covers what when drawing).
      * @return double; the Z-offset for drawing (what's on top, what's underneath).
      */
     protected abstract double getZ();
 
     /**
      * Retrieve the center line of this CrossSectionElement.
      * @return OTSLine3D; the center line of this CrossSectionElement
      */
     public final OTSLine3D getCenterLine()
     {
         return this.centerLine;
     }
 
     /**
      * Retrieve the contour of this CrossSectionElement.
      * @return OTSShape; the contour of this CrossSectionElement
      */
     public final OTSShape getContour()
     {
         return this.contour;
     }
 
     /**
      * Retrieve the id of this CrossSectionElement.
      * @return String; the id of this CrossSectionElement
      */
     @Override
     public final String getId()
     {
         return this.id;
     }
 
     /**
      * Retrieve the id of this CrossSectionElement.
      * @return String; the id of this CrossSectionElement
      */
     public final String getFullId()
     {
         return getParentLink().getId() + "." + this.id;
     }
 
     /**
      * Return the lateral offset from the design line of the parent Link of the Left or Right boundary of this
      * CrossSectionElement at the specified fractional longitudinal position.
      * @param lateralDirection LateralDirectionality; LEFT, or RIGHT
      * @param fractionalLongitudinalPosition double; ranges from 0.0 (begin of parentLink) to 1.0 (end of parentLink)
      * @return Length
      */
     public final Length getLateralBoundaryPosition(final LateralDirectionality lateralDirection,
             final double fractionalLongitudinalPosition)
     {
         Length designLineOffset;
         Length halfWidth;
         if (this.crossSectionSlices.size() <= 2)
         {
             designLineOffset =
                     Length.interpolate(getDesignLineOffsetAtBegin(), getDesignLineOffsetAtEnd(),
                             fractionalLongitudinalPosition);
             halfWidth = Length.interpolate(getBeginWidth(), getEndWidth(), fractionalLongitudinalPosition).multiplyBy(0.5);
         }
         else
         {
             int sliceNr = calculateSliceNumber(fractionalLongitudinalPosition);
             double startFractionalPosition =
                     this.crossSectionSlices.get(sliceNr).getRelativeLength().si / this.parentLink.getLength().si;
             designLineOffset =
                     Length.interpolate(this.crossSectionSlices.get(sliceNr).getDesignLineOffset(), this.crossSectionSlices
                             .get(sliceNr + 1).getDesignLineOffset(), fractionalLongitudinalPosition
                             - startFractionalPosition);
             halfWidth =
                     Length.interpolate(this.crossSectionSlices.get(sliceNr).getWidth(),
                             this.crossSectionSlices.get(sliceNr + 1).getWidth(),
                             fractionalLongitudinalPosition - startFractionalPosition).multiplyBy(0.5);
         }
 
         switch (lateralDirection)
         {
             case LEFT:
                 return designLineOffset.minus(halfWidth);
             case RIGHT:
                 return designLineOffset.plus(halfWidth);
             default:
                 throw new Error("Bad switch on LateralDirectionality " + lateralDirection);
         }
     }
 
     /**
      * Return the lateral offset from the design line of the parent Link of the Left or Right boundary of this
      * CrossSectionElement at the specified longitudinal position.
      * @param lateralDirection LateralDirectionality; LEFT, or RIGHT
      * @param longitudinalPosition Length; the position along the length of this CrossSectionElement
      * @return Length
      */
     public final Length getLateralBoundaryPosition(final LateralDirectionality lateralDirection,
             final Length longitudinalPosition)
     {
         return getLateralBoundaryPosition(lateralDirection, longitudinalPosition.getSI() / getLength().getSI());
     }
 
     /**
      * Construct a buffer geometry by offsetting the linear geometry line with a distance and constructing a so-called "buffer"
      * around it.
      * @param cse CrossSectionElement; the cross section element to construct the contour for
      * @return OTSShape; the geometry belonging to this CrossSectionElement.
      * @throws OTSGeometryException when construction of the geometry fails
      * @throws NetworkException when the resulting contour is degenerate (cannot happen; we hope)
      */
     public static OTSShape constructContour(final CrossSectionElement cse) throws OTSGeometryException, NetworkException
     {
         OTSPoint3D[] result = null;
 
         if (cse.crossSectionSlices.size() <= 2)
         {
             OTSLine3D crossSectionDesignLine =
                     cse.getParentLink().getDesignLine()
                             .offsetLine(cse.getDesignLineOffsetAtBegin().getSI(), cse.getDesignLineOffsetAtEnd().getSI());
             OTSLine3D rightBoundary =
                     crossSectionDesignLine.offsetLine(-cse.getBeginWidth().getSI() / 2, -cse.getEndWidth().getSI() / 2);
             OTSLine3D leftBoundary =
                     crossSectionDesignLine.offsetLine(cse.getBeginWidth().getSI() / 2, cse.getEndWidth().getSI() / 2);
             result = new OTSPoint3D[rightBoundary.size() + leftBoundary.size() + 1];
             int resultIndex = 0;
             for (int index = 0; index < rightBoundary.size(); index++)
             {
                 result[resultIndex++] = rightBoundary.get(index);
             }
             for (int index = leftBoundary.size(); --index >= 0;)
             {
                 result[resultIndex++] = leftBoundary.get(index);
             }
             result[resultIndex] = rightBoundary.get(0); // close the contour
         }
         else
         {
             List<OTSPoint3D> resultList = new ArrayList<>();
             List<OTSPoint3D> rightBoundary = new ArrayList<>();
             for (int i = 0; i < cse.crossSectionSlices.size() - 1; i++)
             {
                 double plLength = cse.getParentLink().getLength().si;
                 double so = cse.crossSectionSlices.get(i).getDesignLineOffset().si;
                 double eo = cse.crossSectionSlices.get(i + 1).getDesignLineOffset().si;
                 double sw2 = cse.crossSectionSlices.get(i).getWidth().si / 2.0;
                 double ew2 = cse.crossSectionSlices.get(i + 1).getWidth().si / 2.0;
                 double sf = cse.crossSectionSlices.get(i).getRelativeLength().si / plLength;
                 double ef = cse.crossSectionSlices.get(i + 1).getRelativeLength().si / plLength;
                 OTSLine3D crossSectionDesignLine =
                         cse.getParentLink().getDesignLine().extractFractional(sf, ef).offsetLine(so, eo);
                 resultList.addAll(Arrays.asList(crossSectionDesignLine.offsetLine(-sw2, -ew2).getPoints()));
                 rightBoundary.addAll(Arrays.asList(crossSectionDesignLine.offsetLine(sw2, ew2).getPoints()));
             }
             for (int index = rightBoundary.size(); --index >= 0;)
             {
                 resultList.add(rightBoundary.get(index));
             }
             // close the contour (might not be needed)
             resultList.add(resultList.get(0));
             result = resultList.toArray(new OTSPoint3D[] {});
         }
         return OTSShape.createAndCleanOTSShape(result);
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     public DirectedPoint getLocation()
     {
         DirectedPoint centroid = this.contour.getLocation();
         return new DirectedPoint(centroid.x, centroid.y, getZ());
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     public Bounds getBounds()
     {
         return this.contour.getBounds();
     }
 
     /** {@inheritDoc} */
     @Override
     @SuppressWarnings("checkstyle:designforextension")
     public String toString()
     {
         return String.format("CSE offset %.2fm..%.2fm, width %.2fm..%.2fm", getDesignLineOffsetAtBegin().getSI(),
                 getDesignLineOffsetAtEnd().getSI(), getBeginWidth().getSI(), getEndWidth().getSI());
     }
 
     /** {@inheritDoc} */
     @SuppressWarnings("checkstyle:designforextension")
     @Override
     public int hashCode()
     {
         final int prime = 31;
         int result = 1;
         result = prime * result + ((this.id == null) ? 0 : this.id.hashCode());
         result = prime * result + ((this.parentLink == null) ? 0 : this.parentLink.hashCode());
         return result;
     }
 
     /** {@inheritDoc} */
     @SuppressWarnings({ "checkstyle:designforextension", "checkstyle:needbraces" })
     @Override
     public boolean equals(final Object obj)
     {
         if (this == obj)
             return true;
         if (obj == null)
             return false;
         if (getClass() != obj.getClass())
             return false;
         CrossSectionElement other = (CrossSectionElement) obj;
         if (this.id == null)
         {
             if (other.id != null)
                 return false;
         }
         else if (!this.id.equals(other.id))
             return false;
         if (this.parentLink == null)
         {
             if (other.parentLink != null)
                 return false;
         }
         else if (!this.parentLink.equals(other.parentLink))
             return false;
         return true;
     }
 
     /**
      * Clone the CrossSectionElement for e.g., copying a network.
      * @param newParentLink the new link to which the clone belongs
      * @param newSimulator the new simulator for this network
      * @param animation whether to (re)create animation or not
      * @return a clone of this object
      * @throws NetworkException in case the cloning fails
      */
     @SuppressWarnings("checkstyle:designforextension")
     public abstract CrossSectionElement clone(final CrossSectionLink newParentLink,
             final SimulatorInterface.TimeDoubleUnit newSimulator, final boolean animation) throws NetworkException;
 }