[vtkusers] Picking and moving a vertex

[Geoframer]

Hey Henrik,

Thanks for the clarification, I understand your solution but I don't think
it's approperiate for Meisam's and my situation. We, at least  I (and i
presume Meisam does also), use glyphs to create a certain source at each
point. In effect we only have a single mapper (a glyphMapper) and a single
actor (a glyphActor).

So there is no easy way to get from picker.GetMapper() to the approperiate
Actor. In fact when i try what you do I get returned an OpenGLActor... I've
tried asking questions about this on the list before but I didn't get any
responses. In the mean time i did find out (perphaps helpful for Meisam)
that if you use a Glyph3D or Glyph2D you can GeneratePointId's which will
enable you to deduct to which glyph the point you picked is contributing (if
i understand correctly). I on the other hand use the ProgrammableGlyphFilter
which does not have this option so i still remain clueless on how to get
from a pick action to the vertex or glyph-center i want.

Regards - Geofram

On 6/14/07, Henrik Westerberg <henrik.westerberg at crg.es> wrote:
>
>
>
> Hi folks,
>
> Ok, for my app I have a vtk file which consists a bunch
> of blobs. I find actors by first finding the number of blobs:
>
> # some vtk in python
> polyImg = vtkPolyDataReader())
> polyImg.SetFileName(name)
>
> # extract all regions for the blobs
> connImg = vtkPolyDataConnectivityFilter())
> connImg.SetExtractionModeToAllRegions()
> connImg.SetInput(polyImg.GetOutput())
>
> # update to get the number of blobs
> connImg.Update()
>
> # get the number of blobs
> numofblobs = connImg.GetNumberOfExtractedRegions()
>
> The blobs are then extrated into a list of mappers and actors using:
>
> # loop over the number of blobs (i)
> blobMappers.append(vtkPolyDataMapper())
>
> tempImg = vtkPolyDataConnectivityFilter()
> tempImg.SetExtractionModeToSpecifiedRegions()
> tempImg.SetInput(connImg.GetOutput())
> tempImg.AddSpecifiedRegion(i)
>
> blobMappers[i].SetInput(tempImg.GetOutput())
> blobActors.append(vtkActor())
> blobActors[i].SetMapper(blobMappers[i])
>
> ren1.AddActor(blobActors[i])
>
> I can then use vtkPicker.GetMapper() to get the mapper which was picked,
> and therefore the actor as they are created at the same time.
>
> # find the actor
> def handlePick(object, event):
>     mapper =  picker.GetMapper()
>     for i in range(0, numofblobs 1):
>         if mapper == blobMappers[i]:           # find the mapper
>             # do some stuff
>             # i also indicates the correct actor
>
> Reading in all the blobs is a bit slow (100 or so blobs) but it works.
>
> hth,
>
> Henrik
>
>
> -----Original Message-----
> From: vtkusers-bounces+henrik.westerberg=crg.es at vtk.org on behalf of
> Geoframer
> Sent: Thu 6/14/2007 2:00 PM
> To: Meisam Aliroteh
> Cc: vtkusers at vtk.org
> Subject: Re: [vtkusers] Picking and moving a vertex
>
> I think you can at least get the starting position by using the
> picker.GetPickPosition() although this is not your center of the vertex
> but
> the coordinates on the glyph. It is at least in 3D coordinates. To get the
> real starting point you should indeed get the Actor that is picked upon
> and
> use it's GetCenter() to retrieve the center of the glyph.
>
> I haven't been able to pull this off though. When i try to get the Actor
> i'm
> picking on i seem to pick the picker's actor for my GetCenter() always
> returns the middle of the data instead of the middle of the vertex.
>
> In any case I'm quite curious how you can go from a cellId to the
> approperiate vertex... Do you just integer divide by the number of cells
> per
> glyph?
>
> Perhaps Henrik can shed some more light on how you can actually get the
> actor of the glyph when picking?
>
> Regards - Geofram
>
> On 6/13/07, Meisam Aliroteh <meisam.aliroteh at gmail.com> wrote:
> >
> > Hi,
> >
> > I have a polydata and used a sphere source to render the polydata in
> > point-cloud mode (i.e only vertices are rendered, and I use spheres to
> > show these vertices). I want the user to be able to click on any vertex
> > (shpere) and move it in the 3D space (well actually it would be a motion
> > restricted to the current view plane). I used vtkCellPicker and know how
> to
> > figure out which vertex is picked when the user clicks on it. What I
> don't
> > know is how to figure out the motion vector when the user clicks and
> drags a
> > sphere ? I can get the old and new mouse positions from the interactor
> but
> > these are 2D coordinates.
> >
> > I guess what I need is the 3D coordinates of the previous and current
> > mouse positions, so that when I subtract these 3D coordiantes I get a
> motion
> > vector and then I can move the picked vertex by adding this motion
> vector to
> > it. The problem is I don't know how to get the 3D coordinate of the
> mouse
> > pointer using VTK !!!
> >
> > Any ideas?
> >
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>
>
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