Hello,
I have pushed this branch in the ExtraMarkups extension. It offers a few parametric shapes that are controlled by 4 markups control points. More parameters are controlled in the module’s widget. They are all vtkParametricFunction derived objects that are already in the VTK library.
I do not intend to merge it in ExtraMarkups’ main branch right away, since this extension is a dependency of SlicerVMTK. The update is relatively big and may hide trouble. It could be merged if it is considered a value-added update by Slicer core developers. People who build Slicer may evaluate this branch any time.
I admit that it’s hard to find a real-world useful application right now. Anyway, it’s there for any purpose.
Thanks for any input and regards.