java.lang.Object
org.apache.commons.geometry.euclidean.AbstractNSphere<Vector2D>
org.apache.commons.geometry.euclidean.twod.shape.Circle
All Implemented Interfaces:
Region<Vector2D>, Sized, Linecastable2D

public final class Circle extends AbstractNSphere<Vector2D> implements Linecastable2D
Class representing a circle in 2 dimensional Euclidean space.
  • Constructor Details

    • Circle

      private Circle(Vector2D center, double radius, org.apache.commons.numbers.core.Precision.DoubleEquivalence precision)
      Construct a new circle from its component parts.
      Parameters:
      center - the center of the circle
      radius - the circle radius
      precision - precision context used to compare floating point numbers
      Throws:
      IllegalArgumentException - if center is not finite or radius is not finite or is less than or equal to zero as evaluated by the given precision context
  • Method Details

    • getSize

      public double getSize()
      Get the size of the instance.
      Specified by:
      getSize in interface Sized
      Returns:
      the size of the instance
    • getBoundarySize

      public double getBoundarySize()
      Get the size of the boundary of the region. The size is a value in the d-1 dimension space. For example, in Euclidean space, this will be a length in 2D and an area in 3D.
      Specified by:
      getBoundarySize in interface Region<Vector2D>
      Returns:
      the size of the boundary of the region
    • project

      public Vector2D project(Vector2D pt)
      Project a point onto the boundary of the region. Null is returned if the region contains no boundaries (ie, is either full or empty).
      Specified by:
      project in interface Region<Vector2D>
      Parameters:
      pt - pt to project
      Returns:
      projection of the point on the boundary of the region or null if the region does not contain any boundaries
    • toTree

      public RegionBSPTree2D toTree(int segments)
      Return a RegionBSPTree2D representing an approximation of the circle. All points in the approximation are contained in the circle (ie, they lie inside or on the boundary). No guarantees are made regarding the internal structure of the returned tree. Non-boundary split nodes may be used in order to balance the tree and improve performance.

      Choosing an appropriate number of segments for an approximation is a trade-off between size and accuracy: approximations with large numbers of segments more closely match the geometric properties of the circle but at the cost of using larger tree structures. In general, the smallest number of segments that produces an acceptable result should be used.

      Parameters:
      segments - number of line segments to use for the boundary of the circle approximation
      Returns:
      a BSP tree approximation of the circle
      Throws:
      IllegalArgumentException - if segments is less than 3
    • intersections

      public List<Vector2D> intersections(Line line)
      Get the intersections of the given line with this circle. The returned list will contain either 0, 1, or 2 points.
      • 2 points - The line is a secant line and intersects the circle at two distinct points. The points are ordered such that the first point in the list is the first point encountered when traveling in the direction of the line. (In other words, the points are ordered by increasing abscissa value.)
      • 1 point - The line is a tangent line and only intersects the circle at a single point (as evaluated by the circle's precision context).
      • 0 points - The line does not intersect the circle.
      Parameters:
      line - line to intersect with the circle
      Returns:
      a list of intersection points between the given line and this circle
    • firstIntersection

      public Vector2D firstIntersection(Line line)
      Get the first intersection point between the given line and this circle, or null if no such point exists. The "first" intersection point is the first such point encountered when traveling in the direction of the line from infinity.
      Parameters:
      line - line to intersect with the circle
      Returns:
      the first intersection point between the given line and this instance or null if no such point exists
    • linecast

      public List<LinecastPoint2D> linecast(LineConvexSubset segment)
      Intersect the given line subset against the boundaries in this instance, returning a list of all intersections in order of increasing position along the line. An empty list is returned if no intersections are discovered.
      Specified by:
      linecast in interface Linecastable2D
      Parameters:
      segment - line subset to intersect
      Returns:
      a list of computed intersections in order of increasing position along the line
    • linecastFirst

      public LinecastPoint2D linecastFirst(LineConvexSubset segment)
      Intersect the given line subset against the boundaries in this instance, returning the first intersection found when traveling in the direction of the line subset from its start location.
      Specified by:
      linecastFirst in interface Linecastable2D
      Parameters:
      segment - line subset to intersect
      Returns:
      the first intersection found or null if no intersection is found
    • getLinecastStream

      private Stream<LinecastPoint2D> getLinecastStream(LineConvexSubset segment)
      Get a stream containing the linecast intersection points of the given segment with this instance.
      Parameters:
      segment - segment to intersect against this instance
      Returns:
      a stream containing linecast intersection points
    • from

      public static Circle from(Vector2D center, double radius, org.apache.commons.numbers.core.Precision.DoubleEquivalence precision)
      Construct a circle from a center point and radius.
      Parameters:
      center - the center point of the circle
      radius - the circle radius
      precision - precision precision context used to compare floating point numbers
      Returns:
      a circle with the given center and radius
      Throws:
      IllegalArgumentException - if center is not finite or radius is not finite or is less than or equal to zero as evaluated by the given precision context