Class PathInterpolator

Direct Known Subclasses:
PositionPathInterpolator, RotationPathInterpolator, RotPosPathInterpolator, RotPosScalePathInterpolator

public abstract class PathInterpolator extends TransformInterpolator
PathInterpolator behavior. This class defines the base class for all Path Interpolators. Subclasses have access to the computePathInterpolation() method, which computes the currentInterpolationValue given the current time and alpha. The method also computes the currentKnotIndex, which is based on the currentInterpolationValue. The currentInterpolationValue is calculated by linearly interpolating among a series of predefined knots (using the value generated by the specified Alpha object). The first knot must have a value of 0.0 and the last knot must have a value of 1.0. An intermediate knot with index k must have a value strictly greater than any knot with index less than k.
  • Field Details

    • currentInterpolationValue

      protected float currentInterpolationValue
      This value is the ratio between knot values indicated by the currentKnotIndex variable. So if a subclass wanted to interpolate between knot values, it would use the currentKnotIndex to get the bounding knots for the "real" value, then use the currentInterpolationValue to interpolate between the knots. To calculate this variable, a subclass needs to call the computePathInterpolation(alphaValue) method from the subclass's computeTransform() method. Then this variable will hold a valid value which can be used in further calculations by the subclass.
    • currentKnotIndex

      protected int currentKnotIndex
      This value is the index of the current base knot value, as determined by the alpha function. A subclass wishing to interpolate between bounding knots would use this index and the one following it, and would use the currentInterpolationValue variable as the ratio between these indices. To calculate this variable, a subclass needs to call the computePathInterpolation(alphaValue) method from the subclass's computeTransform() method. Then this variable will hold a valid value which can be used in further calculations by the subclass.
  • Constructor Details

    • PathInterpolator

      public PathInterpolator(Alpha alpha, float[] knots)
      Deprecated.
      As of Java 3D version 1.3, replaced by PathInterpolator(Alpha, TransformGroup, float[])
      Constructs a new PathInterpolator object that interpolates between the knot values in the knots array. The array of knots is copied into this PathInterpolator object.
      Parameters:
      alpha - the alpha object for this interpolator.
      knots - an array of knot values that specify interpolation points.
    • PathInterpolator

      public PathInterpolator(Alpha alpha, TransformGroup target, float[] knots)
      Constructs a new PathInterpolator object that interpolates between the knot values in the knots array. The array of knots is copied into this PathInterpolator object.
      Parameters:
      alpha - the alpha object for this interpolator.
      target - the transformgroup node effected by this pathInterpolator
      knots - an array of knot values that specify interpolation points.
      Since:
      Java 3D 1.3
    • PathInterpolator

      public PathInterpolator(Alpha alpha, TransformGroup target, Transform3D axisOfTransform, float[] knots)
      Constructs a new PathInterpolator object that interpolates between the knot values in the knots array. The array of knots is copied into this PathInterpolator object.
      Parameters:
      alpha - the alpha object for this interpolator.
      target - the transform node effected by this positionInterpolator
      axisOfTransform - the transform that defines the local coordinate
      knots - an array of knot values that specify interpolation points.
      Since:
      Java 3D 1.3
  • Method Details

    • getArrayLengths

      public int getArrayLengths()
      Retrieves the length of the knots array.
      Returns:
      the array length
    • setKnot

      public void setKnot(int index, float knot)
      Sets the knot at the specified index for this interpolator.
      Parameters:
      index - the index to be changed
      knot - the new knot value
    • getKnot

      public float getKnot(int index)
      Retrieves the knot at the specified index.
      Parameters:
      index - the index of the value requested
      Returns:
      the interpolator's knot value at the associated index
    • setKnots

      protected void setKnots(float[] knots)
      Replaces the existing array of knot values with the specified array. The array of knots is copied into this interpolator object. Prior to calling this method, subclasses should verify that the lengths of the new knots array and subclass-specific parameter arrays are the same.
      Parameters:
      knots - a new array of knot values that specify interpolation points.
      Since:
      Java 3D 1.2
    • getKnots

      public void getKnots(float[] knots)
      Copies the array of knots from this interpolator into the specified array. The array must be large enough to hold all of the knots.
      Parameters:
      knots - array that will receive the knots.
      Since:
      Java 3D 1.2
    • computePathInterpolation

      protected void computePathInterpolation(float alphaValue)
      Computes the base knot index and interpolation value given the specified value of alpha and the knots[] array. If the index is 0 and there should be no interpolation, both the index variable and the interpolation variable are set to 0. Otherwise, currentKnotIndex is set to the lower index of the two bounding knot points and the currentInterpolationValue variable is set to the ratio of the alpha value between these two bounding knot points.
      Parameters:
      alphaValue - alpha value between 0.0 and 1.0
      Since:
      Java 3D 1.3
    • computePathInterpolation

      protected void computePathInterpolation()
      Deprecated.
      As of Java 3D version 1.3, replaced by computePathInterpolation(float)