[vtk-developers] Hierarchy for vtkFunctionParser

[David Gobbi]

Hi Amy,

I've written a class called vtkProgrammableFunction that has the same
interface as vtkFunctionParser, except that its 'SetFunction' method
accepts a C function (or tcl, python, java function) instead
of a text string.  An example follows:

//-----------
void xSquared(void *userData)
{
  vtkProgrammableFunction *func = (vtkProgrammableFunction *)userData;

  // get the variable values
  x = func->GetScalarVariableValue('x')

  // set the result
  func->SetScalarResult(x*x);
}
  
vtkProgrammableFunction *func = vtkProgrammableFunction::New();
func->SetFunction(xSquared,func);
func->SetFunctionArgDelete(NULL);
//----------

So, I was considering creating the following hierarchy:

        vtkAbstractFunction  (the base class)
        /                \
vtkFunctionParser      vtkProgrammableFunction

and perhaps renaming 'vtkFunctionParser' to 'vtkParsedFunction'
in keeping with VTK naming conventions for derived classes.

Any objections/suggestions?  My thoughts are that these 'vtkFunctions'
could be a very useful for programmable image operations (like 
vtkImageMathematics but more flexible), for programmable warp transforms,
etc.

 - David

--
  David Gobbi, MSc                    dgobbi at irus.rri.on.ca
  Advanced Imaging Research Group
  Robarts Research Institute, University of Western Ontario