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VR-Forces 5.0.1 Developer's Guide
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VR-Forces 5.0.1 Developer's Guide
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Description of one segment of a road.
Derived from information in a DtRailSegment. A road segment is information for traffic in one direction, and is linked to another DtRoadSegment for traffic in the other direction.
Classes | |
| class | DtTmpGeometry |
Public Member Functions | |
| DtRoadSegment () | |
| virtual | ~DtRoadSegment () |
| DtRoadSegment (const DtRoadSegment &orig) | |
| DtRoadSegment & | operator= (const DtRoadSegment &orig) |
| virtual DtRoadSegment * | clone () |
Initialization functions. | |
These functions compute the geometry of the lanes in the road segment. | |
| virtual bool | initializeFromRailSegment (DtRailSegment *railSegment, const Coordinate_System *localCoordinateSystem, bool isDrivingOnLeft, DtRoadSegment *opposingSegment, bool debug=false) |
| virtual bool | calculateTemporaryExitGeometry (const double maxSmallBendRadius, const double vehicleWidth, const double headingChange, const double cosHeadingChange, const double sinHeadingChange, bool debug) |
| virtual bool | calculateTemporaryEntryGeometry (const double headingChange, const double cosHeadingChange, const double sinHeadingChange, bool debug) |
| virtual bool | initializeExitCurve (const double maxSmallBendTurnRadius, const double vehicleWidth, const double headingChange, const double cosHeadingChange, const double sinHeadingChange, bool debug=false) |
| virtual bool | initializeEntryCurve (const double headingChange, const double cosHeadingChange, const double sinHeadingChange, bool debug=false) |
| virtual void | setExitCurvesForEndingLanes () |
| virtual void | connectWithNext (DtRoadSegment *nextSegment, bool isDrivingOnLeft, bool debug, bool fillOpposingSegment=true) |
| virtual void | determineIfIntersectionApproach (const DtRoadSegment *next) |
| virtual bool | allAltitudesDetermined () const |
| virtual void | setAllAltitudesDetermined (const bool b) |
Lane Position Functions | |
These functions perform computations from a one-dimensional position along the centerline of a lane. | |
| virtual DtRoadSegmentPart | segmentPart (const int laneN, const double positionAlongLane) |
| virtual double | distanceFromLaneEnd (const int laneN, const double positionAlongLane) |
| virtual double | evenPositionAlongLane (const double positionAlongLaneA, const int laneA, const int laneB) |
| virtual bool | localPositionFromLanePosition (const int laneN, const double positionAlongLane, const double lateralOffset, bool isDrivingOnLeft, DtVector &localPosition, double &headingOffset, double &distanceBeyond) const |
| virtual bool | lanePositionFromLocalPosition (const DtVector localPosition, const int laneN, bool isDrivingOnLeft, double &positionInLane, double &laneOffset, bool debug) |
Multi-Segment Lane Functions | |
These functions examine whether a lane continues downstream through multiple segments in the path. | |
| virtual int | rightmostContinuingLane () const |
| virtual int | findNearestContinuingLane (const int laneN, const double positionAlongLane, const double lookAheadDistance, bool debug=false) |
| virtual bool | laneContinuesForDistance (const int laneN, const double positionAlongLane, const double lookDistance, double &actualDistance, bool &pathContinues, bool debug=false) |
| virtual int | matchingLane (const double offset) |
Set and Get Functions for Members | |
| virtual double | heading () const |
| virtual void | setHeading (const double h) |
| virtual double | length () const |
| virtual void | setLength (const double l) |
| virtual double | medianWidth () const |
| virtual void | setMedianWidth (const double w) |
| virtual DtString | roadName () const |
| virtual void | setRoadName (const DtString &name) |
| virtual const DtCoordTransform & | segmentToLocalTransform () const |
| virtual void | setSegmentToLocalTransform (const DtCoordTransform &xform) |
| virtual int | numLanes () const |
| virtual void | setNumLanes (const int nLanes) |
| virtual DtLaneSegment * | lanes () |
| virtual const DtLaneSegment * | lanes () const |
| virtual bool | isOneWay () const |
| virtual void | setIsOneWay (const bool oneWay) |
| virtual bool | exitIsRightTurn () const |
| virtual void | setExitIsRightTurn (const bool r) |
| virtual bool | entryIsRightTurn () const |
| virtual void | setEntryIsRightTurn (const bool r) |
| virtual double | entryCurveEndOffset () const |
| virtual void | setEntryCurveEndOffset (const double o) |
| virtual double | exitCurveStartOffset () const |
| virtual void | setExitCurveStartOffset (const double o) |
| virtual bool | isIntersectionApproach () const |
| virtual void | setIsIntersectionApproach (const bool i) |
| virtual double | stopLineSetBack () const |
| virtual void | setStopLineSetBack (const double sb) |
| virtual double | speedLimit () const |
| virtual void | setSpeedLimit (const double limit) |
| virtual double | defaultSpeedLimit (const int numLanes) |
| virtual double | freeFlowSpeed () const |
| virtual void | setFreeFlowSpeed (const double ff) |
| virtual DtRoadSegment * | nextRoadSegment () const |
| virtual void | setNextRoadSegment (DtRoadSegment *s) |
| virtual DtRoadSegment * | previousRoadSegment () const |
| virtual void | setPreviousRoadSegment (DtRoadSegment *s) |
| virtual DtRoadSegment * | opposingSegment () const |
| virtual void | setOpposingSegment (DtRoadSegment *s) |
| virtual bool | isOpposing () const |
| virtual void | setIsOpposing (const bool opposing) |
| virtual DtTmpGeometry * | temporaryGeometry () |
Road Design Constants | |
These functions return constants used to build the road path. They define how some of the geometry of the road features are interpreted as roads. They can be overridden to produce different road interpretations. | |
| virtual double | minIntersectionBendAngle () |
| virtual double | intrxThresholdAngleToConnectEdgeLanes () |
| virtual double | intrxThresholdAngleToConnectAllLanes () |
| virtual double | nonIntrxThresholdAngleToConnectEdgeLanes () |
| virtual double | minimumLaneWidth () |
Protected Member Functions | |
| virtual void | findRightMostAlignedLane (DtRoadSegment *nextSegment, int &rightMostLane, int &nextSegmentRightMostLane, int &numAlignedLanes) |
| virtual void | findLeftMostAlignedLane (DtRoadSegment *nextSegment, int &leftMostLane, int &nextSegmentLeftMostLane, int &numAlignedLanes) |
| DtRoadSegment::DtRoadSegment | ( | ) |
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| DtRoadSegment::DtRoadSegment | ( | const DtRoadSegment & | orig | ) |
| DtRoadSegment& DtRoadSegment::operator= | ( | const DtRoadSegment & | orig | ) |
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Fills in values for lane width, number of lanes, median width, and so forth from the rail segment. Computes a tentative coordinate transform from road segment to local coordinates.
| opposingSegment | If this is null, then this function first creates a segment for traffic going the same direction as the rail begin-end direction, then calls itself recursively to create an opposing segment–a segment for traffic going the opposite direction to the rail segment begin-end direction. |
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Do the calculations for the curves connecting segments to determine the ideal and limiting values, and put into the tmpGeometry for the segment. (This will be used to find and adjust segments that are too short.)
| maxSmallBendRadius | When there is only a small angle between adjacent segments, a circular arc connecting them would have a really large radius. This would extend the curve into each segment really far and cause various problems. This parameter is a max radius limit to use in these cases. |
Called in DtRoadPathFunctions::calculatePathTemporaryGeometry as part of setupRoadFromRailPath.
| vehicleWidth | This is width of a design vehicle. The radius of the curve between segments is kept small enough to prevent a vehicle of this width from moving over the lane edge on the inside of the turn. Except that
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| headingChange | The change in heading to the next segment, in radians (+ to the right). If driving on the left of the road, this value should be negated from the true rail segment geometry. |
| cosHeadingChange | cos of heading change. A parameter to avoid repeated calculation (see initializeEntryCurve() ) |
| sinHeadingChange | sin of headingChange |
| debug | A flag to generate verbose output on the sim console (DtWarn) |
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Do the calculations for the curves connecting segments to determine the ideal and limiting values, and put into the tmpGeometry for the segment. (This will be used to find and adjust segments that are too short.)
| headingChange | The change in heading to the next segment, in radians (+ to the right). If driving on the left of the road, this value should be negated from the true rail segment geometry. |
| cosHeadingChange | cos of heading change. A parameter to avoid repeated calculation (see initializeEntryCurve() ) |
| sinHeadingChange | sin of headingChange |
| debug | A flag to generate verbose output on the sim console (DtWarn) |
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Initializes the exit curve geometry in this segment.
Calls calculateInsideExitCurveGeometry to get the geometry of the constraining lane, then calls calculateExitCurveGeometry on the other lanes.
Assumes the next- and previous road segment pointers have been set already. Assumes the entry curve has already been created.
| maxSmallBendTurnRadius | Not used, will be removed |
| vehicleWidth | Not used, will be removed. |
| headingChange | The change in heading to the next segment, in radians (+ to the right). If driving on the left of the road, this value should be negated from the true rail segment geometry. |
| cosHeadingChange | cos of heading change. A parameter to avoid repeated calculation (see initializeEntryCurve() ) |
| sinHeadingChange | sin of headingChange |
| debug | A flag to generate verbose output on the sim console (DtWarn) |
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Initializes the entry curve geometry in the segment. Assumes that the next- and previous road segment pointers have been set already, and that the lanes have been connected. Uses a pre-computed turn radius for the left edge line of the segment–which comes from the exit curve of the previous segment. This assumes that the left edge of the previous segment connects to the left edge of this segment (the normal case).
| headingChange | The change in heading to the next segment, in radians (+ to the right). If driving on the left of the road, this value should be negated from the true rail segment geometry. |
| cosHeadingChange | cos of heading change. A parameter to avoid repeated calculation (see initializeEntryCurve() ) |
| sinHeadingChange | sin of headingChange |
| debug | A flag to generate verbose output on the sim console (DtWarn) |
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Set the exit curve geometry and straight section length for lanes that don't connect downstream. The function finds the lane that connects that has the biggest (negative) offset for its exit curve, and uses that to set the end point of the lanes that don't connect. The exit curve offset will be set to this biggest offset, and the exit curve length will be set to zero.
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Connects the next and previous segment pointers between this segment and the next one and connects the appropriate lanes via their connecting-upstream and -downstream lane members.
This function uses several parameters to guess which lanes should be connected. In general, if the bend is slight, then lanes in the two segments that are aligned with each other are connected. If the road bends more than nonIntrxThresholdAngleToConnectEdgeLanes, then the right-most lanes are connected instead.
If the connection between segments is a roadway intersection, then intrxThresholdAngleToConnectEdgeLanes is used for the threshold angle. A connection between segments is judged to be an intersection if determineIfIntersectionApproach is true (see that function).
If isDrivingOnLeft is true, then the choice of connected lanes is based on the negation of the bend angle between segments. ie, if the bend angle is 90 degrees to the left, but isDrivingOnLeft is true, then the rightmost lane will be connected to the downstream segment.
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Determine if the downstream connection is an intersection. In this base function, the connection is an intersection if the two connecting segments have different names (attributes of the road feature), if they have different one-way properties, or if the angle to the next segment is greater than minIntersectionBendAngle. If this is an intersection, then only the outer edge, "turn" lane is connected to the next segment.
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This indicates that the altitude lookups needed to make the mySegmentToLocal transform (start and end points of the rail segment) and the slopes above (right edge points even with the start and end) have been found. If this is false, then the altitudes haven't been found yet, possibly because streaming terrain wasn't yet loaded. This is only used when creating the road path.
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Fills in values for lane width, number of lanes, median width, and so forth from the rail segment. Computes a tentative coordinate transform from road segment to local coordinates.
| opposingSegment | If this is null, then this function first creates a segment for traffic going the same direction as the rail begin-end direction, then calls itself recursively to create an opposing segment–a segment for traffic going the opposite direction to the rail segment begin-end direction. |
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Computes road segment part from lane position. LaneN is a 0-based lane number.
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Determines how far the position is from the end of the lane, including the exit curve.
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Determines the position along laneB that is even with the position along laneA. Uses 0-based lane numbers.
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Determine the position in local coordinates from the linear position along the lane and a lateral offset.
| laneN | The 0-based lane number. |
| positionAlongLane | The linear position from the beginning of the entry curve arc. |
| lateralOffset | The distance to the right from the centerline. Note that this is actually the distance toward the outside of the road, so if driving on the left this is the distance to the left of the centerline. |
| isDrivingOnLeft | True if roads are set up to drive on left. This causes the position and heading to be mirrored about the line from segment start point to end point. |
| localPosition | The corresponding position in local coordinates (output). |
| headingOffset | The offset from local "north" (1, 0, 0) of the position. This is based on the position along the entry or exit arc. (output) |
| distanceBeyond | If the position is not on the road segment, this output will indicate how far beyond the end of the segment the position is. |
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Compute the position of the given local position in the given lane of the segment.
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Finds the lane number (0-base) of the right-most lane that connects to the downstream road segment. If no lanes have a connecting downstream lane, then 0 (the right lane) is returned.
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Looks downstream to see if the current lane connects through to the downstream segments. If so, returns the number of the current lane (laneN). If not, returns the lane number of a lane that connects. If there are more than one lanes that connect, it returns the nearest lane. If no lane in the current segment connects through for lookAheadDistance, then the nearest lane that connects to the next segment is returned. If there is no next segment, then the current laneN is returned. Checks segments downstream at least to a lookAheadDistance ahead. Lane numbers are 0-based.
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Checks to see if the given lane continues downstream, connecting to lanes in downstream links, for at least lookDistance. If so, returns true. If not, returns false. If the path(connected segments) ends before the lookDistance, the function will return false; however, pathContinues will also be set to false. Puts the distance the lane does continue in actualDistance.
| laneN | is the current lane; 0-based. |
Find the lane whose centerline offset best matches the given offset. Returns a 0-based lane number (ie right lane is 0).
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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Width of the median. Only applies to 2-way segments. The lanes are offset half this width from the segment left edge.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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Name of the road containing this segment.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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Converts from a road-segment coordinate system to local database coordinates. The road segment coordinate system has +x in the direction from the start point to the end, +y to the right, and +z down. The y direction is the same whether driving on the left or not, so code that uses this transformation has to manually negate the y coordinate and the heading if driving on the left.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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Indicates a positive heading change from the previous segment to this one, and that lanes to the right (outside) of the road have a shorter turn radius. Note that if driving on the left, this function returns the opposite, i.e. it is true if the road turned left on entry into this segment. In that case though the outside lane still has the shorter turn radius.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
Provides the default speed limit for (any) road segment based on number of lanes. Used when the road segment is initialized from a rail segment, when the rail segment's speed is just a default value. Uses the constants defined in DtRoadConstants.
| numLanes | is the number of lanes in one direction. |
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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This is the length of the associated rail segment. This is the same as the length of the straight part of the road segment if the entry and exit curves had 0 setback.
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Get/set the temporary geometry computed from the input rail path; used to identify segments that are too short and remove or realign them so that the resulting path is physically feasible. This function accesses the structure without the const qualifier so that callers may change individual members.
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Finds the rightmost lane that is aligned with a lane in the downstream segment, assuming they are collinear. Returns the lane number (0-based), the corresponding lane number in the downstream lane, and the number of aligned lanes.
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Finds the leftmost lane that is aligned with a lane in the downstream segment, assuming they are collinear. Returns the lane number (0-based), the corresponding lane number in the downstream lane, and the number of aligned lanes.
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This defines how much of an angle between segments is required for the connection to be considered an intersection. Default value 0.7854.
If it is an intersection, then usually only the outer, "turn" lane is connected to the downstream segment (see parameter below). In radians. Note 45 degrees = 0.7854 radians. Note that if the path changes from two-way to one-way or vice versa, it is considered an intersection. TODO– this will be replaced with other information to determine whether there is an intersection.
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This defines a threshold between segments at an intersection that determines how lanes are connected. Default value 0.3.
When the bend is less than this angle, a lane is connected to the downstream lane that it aligns with most closely. E.g. if there is one lane in the upstream segment and two in the downstream, the best connection from the single lane will be to the left lane in the downstream segment, because they are closely aligned. However, when the bend is greater than the threshold, the single lane should be connected to the rightmost downstream lane (for right bends, and vice versa for left). This threshold is normally fairly small because the expected case is that the edge lanes are connected at an intersection.
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This defines a threshold between segments at an intersection that determines whether all aligned lanes should be connected, vs only the inside lane. Default value 0.2.
Intersections can be defined by one-way properties changing, or by the name changing, even if there isn't a bend in the road. If the intersection is fairly straight, then all lanes are aligned. If the bend is less than this angle (radians), all lanes will be connected. This should be less than the above threshold.
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Same as above, but for segments that define a bend in a through street rather than an intersection. Default value 0.7854.
This is expected to be a higher threshold because the usual case should be for aligned lanes to connect; only when there is a significant bend are the lanes matched up from the right (left) edge inward. Making this = max-straight-road-bend-angle means that if a path doesn't bend enough to be an intersection, then the aligned lanes will be connected.
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The minimum lane width expected from the feature data. Default value 2.0.
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The length of the underlying road feature, ie the rail segment.
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Coordinate transformation from segment coordinates to local database coordinates. Segment coordinates have the origin at the rail segment start point and are oriented with x toward the end point, y to the right, and z perpendicular to x and y.
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The segment downstream:
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Refers to the connection to the downstream segment:
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Refers to the connection from the upstream segment:
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TODO – the following two members aren't used. See comment above. Where the entry curve ends and the straight section begins, relative to the segment start X.
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Similarly, where the exit curve starts, relative to the end of the segment.
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These come directly from the rail path, thus there is a connection to only on other road segment before and after. (Future implementation might be of a road network, thuse there would be multiple connections at intersections.)
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These come directly from the rail path, thus there is a connection to only on other road segment before and after. (Future implementation might be of a road network, thuse there would be multiple connections at intersections.)
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These come directly from the rail path, thus there is a connection to only on other road segment before and after. (Future implementation might be of a road network, thuse there would be multiple connections at intersections.)
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Only valid if not a one-way segment.
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A vector of lanes, with lane 0 the right-most, and lane myNumberLanes-1 the left-most (or vice versa for drive-on-the-left roads). This is offset by 1 from the railSegment convention, but matches the array index.
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Indicates that the connection at the downstream end is an intersection. Set in determineIfIntersectionApproach(). Affects whether all lanes are connected to the downstream segment, or just the edge lane.
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Distance before end of straight segment where stop line is located. (Note: in VRF 4.5 – not used yet.)
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If available; 0 indicates not set.
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This is the speed traffic flows on average, irrespective of the legal speed limit above. (Note: in VRF 4.5 – not used yet.)
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The width of the median in this (2-way) segment.
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The name of the road.
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Indicates that this segment goes in the opposite direction of the related rail segment. The opposing segments are filled out in the current implementation (4.5), but are not used.
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This information is used when constructing the road path to find modifications to the segments when they are physically impossible to connect together, ie because they are too short and change direction too quickly. These values are for the inner lane in the bend between segments– ie the lane that is constrained the most by geometry.