com.azalient.api.a.position
Interface IBezier

public interface IBezier

An object that implements a curved band, where the centre line is defined by a 4-point (cubic) bezier curve, and there are two edges which may be at a uniform width or may change linearly from the start width to the end width.

The four control points are labelled p[0], p[1], p[2] and p[3]. The curve has an implied direction, going from p[0] to p[3], but it can be used as the centreline for network objects allowing two-way travel.

The Bezier curve is drawn using a variable number, N, of intermediate points, and these in turn define N-1 straight line segments. N increases with the "curviness" of the line. There is a global parameter for maximum curve resolution which can be reduced to restrict the memory used to store intermediate bezier points.

The control points define the centre line, and two IEdge objects defining the outer edges. The distance of the edges from the centre line is defined by two width values, one at the start, and one at the end. If the widths are different, the width will change at a uniform rate along the length of the curve. This can lead to some unexpected outcomes for curvy curves.

Field Summary

static double

DRAW_ALL Use this as the partFill parameter to fill(IDrawing, int, double) to draw the whole length of the curve

Method Summary

void	addRecalcListener(IRecalcListener rc) Add a listener who will be notified when the shape of the bezier changes - when any of the control points move
IAngle	angleEnd() Returns the bearing angle, relative to North, from point p[2] to point p[3]
IAngle	angleStart() Returns the bearing angle, relative to North, from point p[0] towards p[1]
IBezierAssociate	associate() A reference to the network object that uses this bezier.
IAngle	bearing(int pi, int pj) Returns the bearing angle (relative to North) of control point J from control point I.
ICentre	centre() The centre point, valid only if this bezier is an arc
boolean	closerThan(IBezier that, double gap) Returns true if beziers pass closer than given gap (for turn conflicts etc)
boolean	crosses(IBezier that) Returns true if this Bezier crosses that one
void	draw(IDrawing drw, boolean force, double dz, double width, int rgbSpecial, int arrowDirection, boolean drawDashed, boolean hideHandles, boolean drawBarred) Draw this bezier, with a range of parameters to control the line style, colour, arrows etc.
IXyz	edgePt(int ti, double sign) Returns a point on the edge, given the internal point index and a -1 or +1 for left or right respectively
void	fill(IDrawing drw, int rgb, double partFill) Draw this bezier curve, filling the area from edge to edge.
double	halfWidth(double distance) Returns the half-width at the given distance
double	halfWidthE() Returns the half-width at the End of the curve
double	halfWidthS() Returns the half-width at the Start of the curve
boolean	isArc() Returns true if this bezier is currently a circular arc, with an associated ICentre point
boolean	isArcLeft() Returns true if this arced bezier turns to the left going from p[0] to p[3]
boolean	isFree() Returns true if the bezier is curved, i.e.
boolean	isStraight() Returns true if the bezier is currently straight, and control points p[1] and p[2] are not shown
double	length() Returns the length of the centreline, calculated as the sum of all the internal straight line segment distances.
IUndoable	moveP(int pi, IXyz move) Move the given point [0..3] BY the given move vector
int	n() The number of points in the curve
IXyz	nearest(IXyz point) Returns the nearest point on the bezier to the given point
double	nearest(IXyz pointP, IXyz resultQ, boolean fromStart) Find the nearest point, Q, on the curve to a given point P, which can be anywhere, and return that point and the distance of that point along the bezier.
void	outline(IDrawing drw, int rgb, double lineWidth) Draw the outline of the bezier, in the given colour and width
IXyz	p(int i) Return a control point where i = 0..3
void	p(int i, IXyz pnew) Move one of the control points [0..3] to the new position
IPathway	pathway(boolean forward) Returns the IPathway object associated with the given direction on this bezier.
IPosition	position(double distanceFromStart) Returns a newly-created object containing {point, bearing, gradient} at the given distance along the bezier curve
IXyz	pt(int i) A point in the curve, use n() for number of points
void	recalc() Force the internal points to be recalculated
boolean	selected() Returns true if the bezier is currently selected in the GUI
void	sideShift(IUndoStack us, double d) Move the bezier to the side away from the median by distance 'd'.
void	smooth() Smooth the curve to attempt to make it tangential to any connected curves or straight lines
void	stretch(IUndoStack us, boolean atP3, double stretchBy) Stretch the bezier by the given length.
double	width(double distance) Returns the width at the given distance
double	widthE() Returns the width at the End of the curve
double	widthS() Returns the width at the Start of the curve

Field Detail

DRAW_ALL

static final double DRAW_ALL

Use this as the partFill parameter to fill(IDrawing, int, double) to draw the whole length of the curve

See Also:

Constant Field Values

Method Detail

p

IXyz p(int i)

Return a control point where i = 0..3

p

void p(int i,
       IXyz pnew)

Move one of the control points [0..3] to the new position

n

int n()

The number of points in the curve

pt

IXyz pt(int i)

A point in the curve, use n() for number of points

moveP

IUndoable moveP(int pi,
                IXyz move)

Move the given point [0..3] BY the given move vector

sideShift

void sideShift(IUndoStack us,
               double d)

Move the bezier to the side away from the median by distance 'd'. internally, this is used for lanes, but can be used for any bezier, but the direction of the shift is determined by the driving side. Distance d can be negative.

stretch

void stretch(IUndoStack us,
             boolean atP3,
             double stretchBy)

Stretch the bezier by the given length.

Parameters:

atP3 - if true, the bezier is stretched at the end, at p[3] otherwise it is stretched at the start, at p[0]

isFree

boolean isFree()

Returns true if the bezier is curved, i.e. free-form

isStraight

boolean isStraight()

Returns true if the bezier is currently straight, and control points p[1] and p[2] are not shown

isArc

boolean isArc()

Returns true if this bezier is currently a circular arc, with an associated ICentre point

isArcLeft

boolean isArcLeft()

Returns true if this arced bezier turns to the left going from p[0] to p[3]

selected

boolean selected()

Returns true if the bezier is currently selected in the GUI

addRecalcListener

void addRecalcListener(IRecalcListener rc)

Add a listener who will be notified when the shape of the bezier changes - when any of the control points move

centre

ICentre centre()

The centre point, valid only if this bezier is an arc

associate

IBezierAssociate associate()

A reference to the network object that uses this bezier. This may be an ILane or IWalkway, or something else.

position

IPosition position(double distanceFromStart)

Returns a newly-created object containing {point, bearing, gradient} at the given distance along the bezier curve

recalc

void recalc()

Force the internal points to be recalculated

smooth

void smooth()

Smooth the curve to attempt to make it tangential to any connected curves or straight lines

nearest

IXyz nearest(IXyz point)

Returns the nearest point on the bezier to the given point

closerThan

boolean closerThan(IBezier that,
                   double gap)

Returns true if beziers pass closer than given gap (for turn conflicts etc)

crosses

boolean crosses(IBezier that)

Returns true if this Bezier crosses that one

nearest

double nearest(IXyz pointP,
               IXyz resultQ,
               boolean fromStart)

Find the nearest point, Q, on the curve to a given point P, which can be anywhere, and return that point and the distance of that point along the bezier. If Q is beyond the end of the bezier, then the end-point will be returned.

Parameters:

pointP - [IN] a given point, P, not on the curve

resultQ - [OUT] another point Q, the nearest point on the curve to P

fromStart - set to true if the return distance is from the start of the curve, false if the distance is from the end

pathway

IPathway pathway(boolean forward)

Returns the IPathway object associated with the given direction on this bezier. There are two pathway objects, one in each direction.

bearing

IAngle bearing(int pi,
               int pj)

Returns the bearing angle (relative to North) of control point J from control point I. J can be higher or lower than I, but they should not be equal, and both must be in the range [0..3]

length

double length()

Returns the length of the centreline, calculated as the sum of all the internal straight line segment distances.

halfWidthS

double halfWidthS()

Returns the half-width at the Start of the curve

halfWidthE

double halfWidthE()

Returns the half-width at the End of the curve

halfWidth

double halfWidth(double distance)

Returns the half-width at the given distance

widthS

double widthS()

Returns the width at the Start of the curve

widthE

double widthE()

Returns the width at the End of the curve

width

double width(double distance)

Returns the width at the given distance

angleStart

IAngle angleStart()

Returns the bearing angle, relative to North, from point p[0] towards p[1]

angleEnd

IAngle angleEnd()

Returns the bearing angle, relative to North, from point p[2] to point p[3]

edgePt

IXyz edgePt(int ti,
            double sign)

Returns a point on the edge, given the internal point index and a -1 or +1 for left or right respectively

Parameters:

ti - the index of the point, [0..N-1]

sign - either -1 for the "kerb" edge or +1 for the "median" edge. This side parameter also applies to walkways, but means the same side as for a lane. That is, if it were used for a footpath, to the left of a road, where traffic drives on the left, then it could be argued that the kerb side was the right side, but this is not the case in Commuter.

draw

void draw(IDrawing drw,
          boolean force,
          double dz,
          double width,
          int rgbSpecial,
          int arrowDirection,
          boolean drawDashed,
          boolean hideHandles,
          boolean drawBarred)

Draw this bezier, with a range of parameters to control the line style, colour, arrows etc.

Parameters:

drw - The Drawing handle

force - Force this line to be drawn, regardless of any related Viewable/Aspect states

dz - Translate the line by "dz" in the z-axis. This is a convenience to "lift" the line above the corresponding surface

width - the line width

rgbSpecial - an RGB colour to override the colour from the associated Viewable/Aspect

arrowDirection - -1 or +1 to draw an arrow, as for turns/ signals. zero means no arrow

drawDashed - The dash length is pre-defined and cannot be changed here

hideHandles -

drawBarred - Draws a "T" as in for example when a traffic signal is at red.

fill

void fill(IDrawing drw,
          int rgb,
          double partFill)

Draw this bezier curve, filling the area from edge to edge.

Parameters:

drw - The drawing handle

rgb - THE RGB colour code to use

partFill - set partFill to DRAW_ALL (1.0) to draw entire length of curve
or set it to positive P% to draw from the start to P
or set it to negative P% to draw from P to end.

outline

void outline(IDrawing drw,
             int rgb,
             double lineWidth)

Draw the outline of the bezier, in the given colour and width