[vtk-developers] bug in vtkPointSet::FindCell

[Mathieu Westphal]

There is a bug in vtkPointCell::FindCell

I copy here my mantis bug and associated notes:
http://www.vtk.org/Bug/view.php?id=15573

The current implementation of FindCell/ FindCellWalk is just wrong and not
working in some case :

See atached image.
In the current implementation there is three pass :

1 : FindPoint, Check CellPoint
2 : Check first neighbor
3 : Check CellPoint within tolerance

In the associated image, one can see the the first pass will find red star
and only check Cell 1
the second pass will only check cell 2
the third pass will not check anything more

Cell 3 will never be found.

I propose a solution based on vtkStreamTracer surface implementation, which
walk among neighbors more smartly using pcoords and cell boundary.

See :
https://gitlab.kitware.com/vtk/vtk/blob/master/Filters/FlowPaths/vtkAbstractInterpolatedVelocityField.cxx#L289
[^
<https://gitlab.kitware.com/vtk/vtk/blob/master/Filters/FlowPaths/vtkAbstractInterpolatedVelocityField.cxx#L289>
]

What do you think ?

Mathieu Westphal
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