Package toxi.geom.nurbs

Class KnotVector

java.lang.Object
toxi.geom.nurbs.KnotVector
public class KnotVector extends Object
KnotVector, assembles the knots values of a NURBS and its degree.
Version:
1.0
Author:
sg

  • Constructor Summary

    Constructors
    Constructor
    Description
    KnotVector(float[] knots, int degree)
    Create a Knotvector from the given knot values of the desired degree.

  • Method Summary

    Modifier and Type
    Method
    Description
    double[]
    basisFunctions(float u)
    Gets the basis function values for the given u value.
    double[]
    basisFunctions(int span, float u)
    Calculates the basis function values for the given u value, when it's already known in which span u lies.
    float[][]
    derivBasisFunctions(float u, int grade)
    Calculates the basis functions and its derivatives up to the given grade.
    float[][]
    derivBasisFunctions(int span, float u, int grade)
    Calculates the basis functions and its derivatives up to the given grade.
    int
    findSpan(float u)
    Finds the span (Position of corresponding knot values in knot vector) a given value belongs to.
    float
    get(int i)
    Get the knot value at a specific index.
    float[]
    getArray()
    get the knot values as float array
    int
    getDegree()
    Get the degree of the KnotVector
    int
    getN()
    Return the nu
    int
    getNumberOfSegments()
     
    boolean
    isOpen()
     
    int
    length()
     
    void
    set(int i, float val)
    Set the knot value at a specific index.

    Methods inherited from class java.lang.Object

    equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • KnotVector

      public KnotVector(float[] knots, int degree) throws IllegalArgumentException
      Create a Knotvector from the given knot values of the desired degree.
      Parameters:
      knots - knot values
      degree - degree of Nurbs
      Throws:
      IllegalArgumentException

  • Method Details

    • basisFunctions

      public double[] basisFunctions(float u)
      Gets the basis function values for the given u value. This function calculates firstly the span which is needed in order to calculate the basis functions values.
      Parameters:
      u - Value to calculate basis functions for.
      Returns:
      basis function values

    • basisFunctions

      public double[] basisFunctions(int span, float u)
      Calculates the basis function values for the given u value, when it's already known in which span u lies.
      Parameters:
      span - The span u lies in
      u - Value to calculate basis functions for.
      Returns:
      basis function values

    • derivBasisFunctions

      public float[][] derivBasisFunctions(float u, int grade)
      Calculates the basis functions and its derivatives up to the given grade.
      Parameters:
      u - Value to calculate basis functions and derivatives for.
      grade - grade to calculate derivations for.
      Returns:
      an array of basis function values or derivated basis functions values. The first array is the degree of dderivation in the second array rhe values are stored.
      Example:
      float[]][] f=dersBasisFuns(0.1f, 3); float value=f[0][1]; //In value is know the second value of the basis function derived 0 times stored.

    • derivBasisFunctions

      public float[][] derivBasisFunctions(int span, float u, int grade)
      Calculates the basis functions and its derivatives up to the given grade.
      Parameters:
      span - Span the given value lies in.
      u - Value to calculate basis functions and derivatives for.
      grade - grade to calculate derivations for.
      Returns:
      an array of basis function values or derivated basis functions values
      See Also:

    • findSpan

      public int findSpan(float u)
      Finds the span (Position of corresponding knot values in knot vector) a given value belongs to.
      Parameters:
      u - value to find span for
      Returns:
      Position of span.

    • get

      public float get(int i)
      Get the knot value at a specific index.
      Parameters:
      i - Index to get knot value for
      Returns:
      the knot value

    • getArray

      public float[] getArray()
      get the knot values as float array
      Returns:
      the knot values

    • getDegree

      public int getDegree()
      Get the degree of the KnotVector
      Returns:
      Degree of the Knotvector

    • getN

      public int getN()
      Return the nu
      Returns:
      Length of the KnotVector

    • getNumberOfSegments

      public int getNumberOfSegments()

    • isOpen

      public boolean isOpen()

    • length

      public int length()

    • set

      public void set(int i, float val)
      Set the knot value at a specific index. After this operation a call to isValid may be needed if one is not sure if the KnotVector with the changed value is valid for a Nurbs.
      Parameters:
      i - Index to set knot value
      val - value to set the knot too