Package org.djutils.draw.curve

Interface Curve<DP,DIR,P extends Point<P>,F extends Flattener<F,?,PL,P,DIR>,PL extends PolyLine<?,P,?,?,?>>

Type Parameters:
DP - the DirectedPoint type
DIR - the direction type. In 2d this is a java.lang.Double; in 3d this is a Direction3d object
P - the Point type
F - the Flattener type
PL - the PolyLine type
All Known Subinterfaces:
Curve2d, Curve3d, OffsetCurve2d
All Known Implementing Classes:
Arc2d, Bezier2d, Bezier3d, BezierCubic2d, BezierCubic3d, Clothoid2d, Straight2d
public interface Curve<DP,DIR,P extends Point<P>,F extends Flattener<F,?,PL,P,DIR>,PL extends PolyLine<?,P,?,?,?>>
A Curve defines a line in an exact, continuous manner, from which numerically approximated polylines can be derived. The continuous definition is useful to accurately connect different lines, e.g. based on the direction of the point where they meet. Moreover, this direction may be accurately be determined by either of the lines. For example, an arc can be defined up to a certain angle. Whatever the angle of the last line segment in a polyline for the arc may be, the continuous line contains the final direction exactly. The continuous definition is also useful to define accurate offset lines, which depend on accurate directions especially at the line end points.

Copyright (c) 2024-2025 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See for project information https://djutils.org. The DJUTILS project is distributed under a three-clause BSD-style license, which can be found at https://djutils.org/docs/license.html.

Author:
Alexander Verbraeck, Peter Knoppers, Wouter Schakel

  • Method Summary

    Modifier and Type
    Method
    Description
    DIR
    getDirection(double fraction)
    Returns the direction at the given fraction.
    DIR
    getEndDirection()
    End direction of this Curve.
    DP
    getEndPoint()
    End point of this Curve.
    default Set<Double>
    getKnots()
    If this Curve has knots, this method must return the fractions where those knots occur.
    double
    getLength()
    Return the length of this Curve.
    P
    getPoint(double fraction)
    Returns the point at the given fraction of this Curve.
    DIR
    getStartDirection()
    Start direction of this Curve.
    DP
    getStartPoint()
    Start point of this Curve.
    PL
    toPolyLine(F flattener)
    Flatten a Curve into a PolyLine.

  • Method Details

    • getStartPoint

      DP getStartPoint()
      Start point of this Curve.
      Returns:
      start point of this Curve

    • getEndPoint

      DP getEndPoint()
      End point of this Curve.
      Returns:
      end point of this Curve

    • getLength

      double getLength()
      Return the length of this Curve.
      Returns:
      length of this Curve

    • getStartDirection

      DIR getStartDirection()
      Start direction of this Curve.
      Returns:
      start direction of this Curve

    • getEndDirection

      DIR getEndDirection()
      End direction of this Curve.
      Returns:
      end direction of this Curve

    • toPolyLine

      PL toPolyLine(F flattener)
      Flatten a Curve into a PolyLine. Implementations should use the flattener when relevant and possible.
      Parameters:
      flattener - the flattener
      Returns:
      approximation of this Curve as a PolyLine

    • getPoint

      P getPoint(double fraction)
      Returns the point at the given fraction of this Curve. The fraction may represent any parameter, such as t in a Bézier curve, s in a Clothoid, or simply the fraction of length.
      Parameters:
      fraction - the fraction
      Returns:
      the point at the given fraction

    • getKnots

      default Set<Double> getKnots()
      If this Curve has knots, this method must return the fractions where those knots occur. The default implementation works for Curves that have no knots.
      Returns:
      Set<Double> the fractions where knots in the offset function occur, may be empty or null

    • getDirection

      DIR getDirection(double fraction)
      Returns the direction at the given fraction. The fraction may represent any parameter, such as t in a Bézier curve, s in a Clothoid, or simply the fraction of length. The default implementation performs a numerical approach by looking at the direction between the points at fraction, and a point 1e-6 away.
      Parameters:
      fraction - the fraction
      Returns:
      the direction at the given fraction