Headway.java
package org.opentrafficsim.road.gtu.lane.perception.headway;
import org.djunits.value.vdouble.scalar.Acceleration;
import org.djunits.value.vdouble.scalar.Length;
import org.djunits.value.vdouble.scalar.Speed;
import org.opentrafficsim.core.perception.PerceivedObject;
/**
* Interface for a reference to information about a (lane based) GTU and a headway. The Headway can store information about GTUs
* or objects ahead of the reference GTU, behind the reference GTU, or (partially) parallel to the reference GTU. In addition to
* the (perceived) headway, several other pieces of information can be stored, such as (perceived) speed, (perceived)
* acceleration, (perceived) turn indicators, and (perceived) braking lights. <br>
* Special care must be taken in curves when perceiving headway of a GTU or object on an adjacent lane.The question is whether
* we perceive the parallel or ahead/behind based on a line perpendicular to the front/back of the GTU (rectangular), or
* perpendicular to the center line of the lane (wedge-shaped in case of a curve). The difficulty of a wedge-shaped situation is
* that reciprocity might be violated: in case of a clothoid, for instance, it is not sure that the point on the center line
* when projected from lane 1 to lane 2 is the same as the projection from lane 2 to lane 1. The same holds for shapes with
* sharp bends. Therefore, algorithms implementing headway should only project the <i>reference point</i> of the reference GTU
* on the center line of the adjacent lane, and then calculate the forward position and backward position on the adjacent lane
* based on the reference point. Still, our human perception of what is parallel and what not, is not reflected by fractional
* positions. See examples in
* <a href= "http://simulation.tudelft.nl:8085/browse/OTS-113">http://simulation.tudelft.nl:8085/browse/OTS-113</a>.
* <p>
* Copyright (c) 2013-2019 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>
* @version $Revision: 1368 $, $LastChangedDate: 2015-09-02 00:20:20 +0200 (Wed, 02 Sep 2015) $, by $Author: averbraeck $,
* initial version 11 feb. 2015 <br>
* @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
* @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
*/
public interface Headway extends PerceivedObject, Comparable<Headway>
{
/** the object types that can be distinguished for headway. */
enum ObjectType
{
/** the observed object for headway is a GTU. */
GTU,
/** the observed object for headway is a traffic light. */
TRAFFICLIGHT,
/** the observed object for headway is a generic object. */
OBJECT,
/** there is no observed object, just a distance. */
DISTANCEONLY,
/** intersection conflict. */
CONFLICT,
/** stop line. */
STOPLINE,
/** bus stop. */
BUSSTOP;
/** @return whether this object is a GTU or not. */
public boolean isGtu()
{
return this.equals(GTU);
}
/** @return whether this object is a GTU or not. */
public boolean isTrafficLight()
{
return this.equals(TRAFFICLIGHT);
}
/** @return whether this object is an object or not. */
public boolean isObject()
{
return this.equals(OBJECT);
}
/** @return whether no object was observed and only a distance was stored. */
public boolean isDistanceOnly()
{
return this.equals(DISTANCEONLY);
}
/** @return whether this object is a conflict or not. */
public boolean isConflict()
{
return this.equals(CONFLICT);
}
/** @return whether this object is a stop line or not. */
public boolean isStopLine()
{
return this.equals(STOPLINE);
}
/** @return whether this object is a bus stop or not. */
public boolean isBusStop()
{
return this.equals(BUSSTOP);
}
}
/**
* @return String; the id of the other object for comparison purposes, cannot be null.
*/
@Override
String getId();
/**
* @return Length; the length of the other object; can be null if unknown.
*/
Length getLength();
/**
* @return Speed; the (perceived) speed of the other object; can be null if unknown.
*/
Speed getSpeed();
/**
* Retrieve the strongly typed distance to the other object.
* @return Length; the distance to the object, return value null indicates that the other object is parallel to the
* reference object
*/
Length getDistance();
/**
* @return Length; the (perceived) object Type, can be null if no object type unknown.
*/
ObjectType getObjectType();
/**
* @return Acceleration; acceleration the (perceived) acceleration of the other object; can be null if unknown.
*/
Acceleration getAcceleration();
/**
* Return the (perceived) front overlap to the other object. This value should be null if there is no overlap. In the figure
* for two GTUs below, it is distance c, positive for GTU1, negative for GTU2.
*
* <pre>
* ----------
* | GTU 1 | ----->
* ----------
* ---------------
* | GTU 2 | ----->
* ---------------
* | a | b | c |
* </pre>
*
* @return Length; the (perceived) front overlap to the other object or null if there is no overlap.
*/
Length getOverlapFront();
/**
* Return the (perceived) rear overlap to the other object. This value should be null if there is no overlap.In the figure
* below for two GTUs, it is distance a, positive for GTU1, negative for GTU2.
*
* <pre>
* ----------
* | GTU 1 | ----->
* ----------
* ---------------
* | GTU 2 | ----->
* ---------------
* | a | b | c |
* </pre>
*
* @return Length; the (perceived) rear overlap to the other object or null if there is no overlap.
*/
Length getOverlapRear();
/**
* Return the (perceived) overlap with the other object. This value should be null if there is no overlap. In the figure
* below for two GTUs, it is distance b, positive for GTU1 and GTU2.
*
* <pre>
* ----------
* | GTU 1 | ----->
* ----------
* ---------------
* | GTU 2 | ----->
* ---------------
* | a | b | c |
* </pre>
*
* @return Length, the (perceived) overlap with the other object or null if there is no overlap.
*/
Length getOverlap();
/**
* @return whether the other object is in front of the reference object.
*/
boolean isAhead();
/**
* @return whether the other object is behind the reference object.
*/
boolean isBehind();
/**
* @return whether the other object is parallel the reference object.
*/
boolean isParallel();
/** {@inheritDoc} */
@Override
default int compareTo(final Headway headway)
{
if (getDistance() != null)
{
if (headway.getDistance() != null)
{
return getDistance().compareTo(headway.getDistance());
}
return 1;
}
else if (headway.getDistance() != null)
{
return -1;
}
return getOverlapFront().compareTo(headway.getOverlapFront());
}
}