[vtk-developers] vtkColorTransferFunction ambiguities about ranges

[Sean McBride]

Hi all,

I'm debugging another undefined behaviour found by clang (converting large doubles into uint8, again with colour conversions).

I'm finding the docs for vtkColorTransferFunction are not detailed enough.  Specifically:

  // Description:
  // Add/Remove a point to/from the function defined in RGB or HSV
  // Return the index of the point (0 based), or -1 on error.
  // See the description of class vtkPiecewiseFunction for an explanation of
  // midpoint and sharpness.
  int AddRGBPoint( double x, double r, double g, double b );
  int AddRGBPoint( double x, double r, double g, double b,
                   double midpoint, double sharpness );
  int AddHSVPoint( double x, double h, double s, double v );
  int AddHSVPoint( double x, double h, double s, double v,
                   double midpoint, double sharpness );

What is the allowable/required/expected range of these things?  Should RGB values always be 0 to 1?  Likewise for HSV?  Is hue 0 to 1?  0 to 2π?  0 to 360?  etc.  Am I just missing where this is documented?

Cheers,

-- 
____________________________________________________________
Sean McBride, B. Eng                 sean at rogue-research.com
Rogue Research                        www.rogue-research.com 
Mac Software Developer              Montréal, Québec, Canada