vtkColorTransferFunction"Index out of range!"

This is a bug report but I was unsure whether to post it in vtk/vtk or paraview/paraview.

Reproduce:

  • enable volume rendering on something (just to have the mapping data show up)
  • In mapping data: add more points (nodes) in the opacity transfer function than in the Color transfer functions
  • hover your mouse over the Opacity transfer function graph: you get
(1712.476s) [paraview        ]vtkColorTransferFunctio:1277   ERR| vtkPVDiscretizableColorTransferFunction (0x55e84103da50): Index out of range!

Brief analysis

Warning is raised here:
https://gitlab.kitware.com/vtk/vtk/-/blob/4b9e1acc53af9ccf54df4b0c78909ff172319a71/Rendering/Core/vtkColorTransferFunction.cxx#L1274

The issue here is that the this->Internal->Nodes.size() there always returns the number of nodes in the color transfer function (try it out yourself with a print), even when used in the opacity transfer functions. I tried for quite some time to figure out why but eventually couldn’t so I’m raising this issue.

Have a great day

I just opened an issue on gitlab.