[vtkusers] Reflecting vtkPolyData about a plane

David.Pont at ForestResearch.co.nz David.Pont at ForestResearch.co.nz
Sun Jan 9 19:31:05 EST 2005

"Ben Held" <ben.held at staarinc.com> wrote on 31/12/2004 01:59:15:

Here are a couple of rough ideas:
 A vtkTransform with Scale set to -1 (for one of X, Y or Z) will reflect
through an axis aligned plane.
See the code for vtkPlaneSource for techniques to use transforms with
planes of arbitrary orientation (defined either with center and normal or
corner points). You could use you plane location/orientation to derive
transforms applied to your polydata, first to transform from current
position to an axis aligned position, then to reflect, then reverse the
intial transform to return to 'current' position (but reflected) ... ?
Would correctly specified XYZ Scale values, normalised to represent a unit
vector (negative), reflect in an arbitrary plane ?
   Dave P

> Hi Amy,
> Thanks for the advice.  However, I need to reflect about non-axis-aligned
> planes too.
> Ben
> -----Original Message-----
> From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org]On
> Behalf Of Amy Henderson
> Sent: Wednesday, December 29, 2004 2:55 PM
> To: vtkusers at public.kitware.com
> Subject: Re: [vtkusers] Reflecting vtkPolyData about a plane
> Hi Ben,
> If you want to reflect about an axis-aligned plane (X=, Y=, or Z=), then
> try using vtkReflectionFilter.  It can take a vtkPolyData as input, but
> produces a vtkUnstructuredGrid as output.
> - Amy
> At 02:16 PM 12/29/2004, Ben Held wrote:
> >Is there an easy way to reflect a vtkPolyData about a plane?  I have
> >into vtkTransformPolyData, but I don't see a direct way to create a
> >vtkTransform that represnets a reflection?
> >
> >Thanks in adavance.
> >

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