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DtLaneSegment::DtLaneGeometry Struct Reference

The geometry of the lane, especially the parameters of the circular arcs that define the entry and exit curves. More...

Public Attributes

double myLaneOffsetDistance
 This is the lateral offset (in y) from the segment origin to the centerline of this lane.
double myStraightSectionLength
 This is the length of the straight section between the entry and exit curves.
double myWidth
double myEntryCurveRadius
 Entry curve:Arc radius.
double myEntryCurveLength
 This is the length of the arc from the midpoint of the turn to where it joins the straight part of the lane segment.
double myEntryCurveEndOffset
 The offset in X from the segment origin to the end of the entry arc; marks the beginning of the straight part of the lane.
double myExitCurveRadius
 Exit curve, at end of segment:
double myExitCurveLength
double myExitCurveStartOffset
 This offset is normally negative, meaning that the curve starts before the end of the segment.

Detailed Description

The geometry of the lane, especially the parameters of the circular arcs that define the entry and exit curves.

Road segments are derived from rail segments and are defined as a straight piece of road between two points with some number of lanes traveling in one direction. (For two-way rail segments, there are two corresponding road segments, one in each direction.) The lanes in each segment are joined to the lanes in the next and previous segments by circular arcs of the same radius. Thus each road segment lane has a "half-arc" at the beginning and a "half-arc" at the end.

The entry arc for a lane (DtLaneSegment) may start before the beginning of the rail segment, if the path bends to the left at the beginning of the rail segment. The entry arc will continue into the lane until it ends with the lane centerline touching the arc. The distance into the lane, past the start of the rail segment, is the "offset" of the entry curve end. Similarly, exit curves start at an offset before the end of the segment. Thus

Rail segment length = entryCurveEndOffset + myStraightSectionLength - exitCurveStartOffset.

All of the points in this class are points in a 2D coordinate system that has an origin at the start of the left edge of the road segment with x axis in the direction of the straight part of the segment, and the y axis to the right.

Member Data Documentation

double DtLaneSegment::DtLaneGeometry::myLaneOffsetDistance

This is the lateral offset (in y) from the segment origin to the centerline of this lane.

For lane N-1 (leftmost lane) this is half the width of lane N-1; for lane N-2 it is the width of lane N-1 plus half of N-2; etc. If there is a median in a two-way segment, then the offset is increased by half the median width.

double DtLaneSegment::DtLaneGeometry::myEntryCurveRadius

Entry curve:Arc radius.

Note that the arc center is at (myEntryCurveEndOffset, myLaneOffsetDistance + myEntryCurveRadius) in segment coordinates.

If the radius is 0, this indicates that there is no arc (arc length and offset will be 0 as well).

double DtLaneSegment::DtLaneGeometry::myEntryCurveLength

This is the length of the arc from the midpoint of the turn to where it joins the straight part of the lane segment.

double DtLaneSegment::DtLaneGeometry::myEntryCurveEndOffset

The offset in X from the segment origin to the end of the entry arc; marks the beginning of the straight part of the lane.

double DtLaneSegment::DtLaneGeometry::myStraightSectionLength

This is the length of the straight section between the entry and exit curves.

If this road segment and the ones before and after have the same lane widths, then this length will be the same for all lanes in the segment.

double DtLaneSegment::DtLaneGeometry::myExitCurveRadius

Exit curve, at end of segment:

double DtLaneSegment::DtLaneGeometry::myExitCurveLength
double DtLaneSegment::DtLaneGeometry::myExitCurveStartOffset

This offset is normally negative, meaning that the curve starts before the end of the segment.

double DtLaneSegment::DtLaneGeometry::myWidth

The documentation for this struct was generated from the following file:

Document ID: Generated on Thu Mar 23 18:54:12 EDT 2017 from SVN revision 174804
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