Class Vertex

java.lang.Object
org.locationtech.jts.triangulate.quadedge.Vertex
Direct Known Subclasses:
ConstraintVertex
public class Vertex extends Object
Models a site (node) in a QuadEdgeSubdivision. The sites can be points on a line string representing a linear site.

The vertex can be considered as a vector with a norm, length, inner product, cross product, etc. Additionally, point relations (e.g., is a point to the left of a line, the circle defined by this point and two others, etc.) are also defined in this class.

It is common to want to attach user-defined data to the vertices of a subdivision. One way to do this is to subclass Vertex to carry any desired information.

Author:
David Skea, Martin Davis

  • Field Details

  • Constructor Details

    • Vertex

      public Vertex(double _x, double _y)

    • Vertex

      public Vertex(double _x, double _y, double _z)

    • Vertex

      public Vertex(Coordinate _p)

  • Method Details

    • getX

      public double getX()

    • getY

      public double getY()

    • getZ

      public double getZ()

    • setZ

      public void setZ(double _z)

    • getCoordinate

      public Coordinate getCoordinate()

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • equals

      public boolean equals(Vertex _x)

    • equals

      public boolean equals(Vertex _x, double tolerance)

    • classify

      public int classify(Vertex p0, Vertex p1)

    • isInCircle

      public boolean isInCircle(Vertex a, Vertex b, Vertex c)
      Tests if the vertex is inside the circle defined by the triangle with vertices a, b, c (oriented counter-clockwise).
      Parameters:
      a - a vertex of the triangle
      b - a vertex of the triangle
      c - a vertex of the triangle
      Returns:
      true if this vertex is in the circumcircle of (a,b,c)

    • isCCW

      public final boolean isCCW(Vertex b, Vertex c)
      Tests whether the triangle formed by this vertex and two other vertices is in CCW orientation.
      Parameters:
      b - a vertex
      c - a vertex
      Returns:
      true if the triangle is oriented CCW

    • rightOf

      public final boolean rightOf(QuadEdge e)

    • leftOf

      public final boolean leftOf(QuadEdge e)

    • circumRadiusRatio

      public double circumRadiusRatio(Vertex b, Vertex c)
      Computes the value of the ratio of the circumradius to shortest edge. If smaller than some given tolerance B, the associated triangle is considered skinny. For an equal lateral triangle this value is 0.57735. The ratio is related to the minimum triangle angle theta by: circumRadius/shortestEdge = 1/(2sin(theta)).
      Parameters:
      b - second vertex of the triangle
      c - third vertex of the triangle
      Returns:
      ratio of circumradius to shortest edge.

    • midPoint

      public Vertex midPoint(Vertex a)
      returns a new vertex that is mid-way between this vertex and another end point.
      Parameters:
      a - the other end point.
      Returns:
      the point mid-way between this and that.

    • circleCenter

      public Vertex circleCenter(Vertex b, Vertex c)
      Computes the centre of the circumcircle of this vertex and two others.
      Parameters:
      b -
      c -
      Returns:
      the Coordinate which is the circumcircle of the 3 points.

    • interpolateZValue

      public double interpolateZValue(Vertex v0, Vertex v1, Vertex v2)
      For this vertex enclosed in a triangle defined by three vertices v0, v1 and v2, interpolate a z value from the surrounding vertices.

    • interpolateZ

      public static double interpolateZ(Coordinate p, Coordinate v0, Coordinate v1, Coordinate v2)
      Interpolates the Z-value (height) of a point enclosed in a triangle whose vertices all have Z values. The containing triangle must not be degenerate (in other words, the three vertices must enclose a non-zero area).
      Parameters:
      p - the point to interpolate the Z value of
      v0 - a vertex of a triangle containing the p
      v1 - a vertex of a triangle containing the p
      v2 - a vertex of a triangle containing the p
      Returns:
      the interpolated Z-value (height) of the point

    • interpolateZ

      public static double interpolateZ(Coordinate p, Coordinate p0, Coordinate p1)
      Computes the interpolated Z-value for a point p lying on the segment p0-p1
      Parameters:
      p -
      p0 -
      p1 -
      Returns:
      the interpolated Z value