[vtk-developers] vtkColorTransferFunction

[Miller, James V (CRD)]

Lisa,

I just saw your message below.  While I am not relying on having 3 piecewise functions in the color
transfer function, I am sorry to see them leave :) (I do rely heavily on the methods BuildTable and
BuildFunctionFromTable, so please do not remove them :)

I have written GUI's that operated on piecewise functions.  With a single line of code, I could have
the GUI operate on a specified channel of the piecewise function. It was nice way to reuse a GUI to
operate on a piecewise function or a color transfer function.  I'll have to look at your changes in
more depth to see how I could do the same thing now.

As an aside, if I had seen this message earlier, I would have pushed to have you create a new
subclass rather than change the current class.  I think its getting pretty late in the VTK game to
remove a portion of the API.

Jim



-----Original Message-----
From: Lisa Sobierajski Avila [mailto:lisa.avila at kitware.com]
Sent: Thursday, June 22, 2000 11:11 AM
To: vtk-developers at public.kitware.com
Subject: [vtk-developers] vtkColorTransferFunction


Hello,

I am make some modifications to vtkColorTransferFunction, and I have 
determined that I have two choices on how to proceed:


1)  Modify vtkColorTransferFunction so that R, G, and B are no longer 
independent. That means the AddRedPoint, AddGreenPoint, AddBluePoint, can 
remain, but will actually probe the current function to get the other two, 
then AddRGBPoint. The methods that would disappear would be GetRedFunction, 
GetGreenFunction, and GetBlueFunction since this won't use three 
vtkPiecewiseFunctions as the underlying representation.

2) Create a new subclass of vtkColorToScalar that supports the 
functionality I am looking for. This will also support all of the current 
vtkColorTransferFunction functionality except for the independence of the 
functions.


Is anyone out there using the red, green, and blue functions independently? 
I'd rather not see two classes that do almost the same thing, but my 
changes will essentially break some methods.

Any comments?


Lisa




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