[vtkusers] question about implicit surfaces and extractPolyDataGeometry - trying to produce a triangle mesh of a cylinder

[David Gobbi]

Hi Michel,

The best way to produce a cylinder is usually to use vtkLineSource,
followed by vtkTubeFilter.  Use vtkLineSource::SetResolution to set
the resolution along the line, and vtkTubeFilter::SetNumberOfSides to
set the resolution around the cylinder.

Also, vtkTubeFilter::CappingOn() can be used to set whether the ends
of the cylinder are open or closed.

 - David

On Thu, Jul 18, 2013 at 12:52 PM, Audette, Michel A. <maudette at odu.edu> wrote:
> Dear VTK users,
>
> I would like to use a cylindrical implicit function in order to produce a
> triangulated cylindrical mesh. Looking at the testing example
> extractPolyData.tcl , which includes the code below, I see both a
> cylindrical function used as implicit function, as well as a sphere source
> which is used in conjunction with SetInputConnection. Can someone illuminate
> me on what purpose is served by the latter?
>
> If not, how can I produce a triangulated surface mesh of a cylinder, e.g.
> vtkCylinder?
>
> Here is the relevant code in the tcl test file.
>
> vtkSphereSource sphere
>   sphere SetThetaResolution 8
>   sphere SetPhiResolution 16
>   sphere SetRadius 1.5
>
> # Extraction stuff
> vtkTransform t
>     t RotateX 90
> vtkCylinder cylfunc
>     cylfunc SetRadius 0.5
>     cylfunc SetTransform t
> vtkExtractPolyDataGeometry extract
>     extract SetInputConnection [sphere GetOutputPort]
>     extract SetImplicitFunction cylfunc
>     extract ExtractBoundaryCellsOn
>
> vtkPolyDataMapper  sphereMapper
>     sphereMapper SetInputConnection [extract GetOutputPort]
>     sphereMapper GlobalImmediateModeRenderingOn
>
> vtkActor sphereActor
>     sphereActor SetMapper sphereMapper
>
> Thanks for your support.
>
> Michel
> Michel Audette, Ph.D.
> Assistant Professor,
> Department of Modeling, Simulation and Visualization Engineering,
> Old Dominion University,
> Norfolk, VA.