[vtkusers] mixing vtkImageActor with solidly rendered vtkPolyData

[Mathieu Coursolle]

Where is SetResolveCoincidentTopologyToPolygonOffset activated?

Can it be activated at the mapper level? 
Would it be possible to activated your polydata mappers, but
not the image actor then?

Mathieu

>Hi Mathieu, 
>
>yes, I use vtkImageViewer2.  I am wondering:
>if SetResolveCoincidentTopologyToPolygonOffset
>is activated, then both the vtkOpenGLPolyDataMapper
>and the vtkOpenGLImageActor do this:
>
>#ifdef GL_VERSION_1_1
>      double f, u;
>      glEnable(GL_POLYGON_OFFSET_FILL);
>      vtkMapper::GetResolveCoincidentTopologyPolygonOffsetParameters(f,u);
>      glPolygonOffset(f,u);
>#endif 
>
>So, are both mappers just shifing the image actor
>and the actor rendering the polygon the same amount,
>(or shifting the image actor in front of the 
>polygon actor) thereby negating the desired effect?
>If so, would it be useful/desirable to be able to 
>turn off shifting at the individual actor level?
>
>Dean
>
>> Subject: Re: [vtkusers] mixing vtkImageActor with solidly rendered
>>  vtkPolyData
>> 
>> I don't know why you only see your wireframe actors.
>> Are you using a vtkImageViewer2?
>> 
>> The following is taken from vtkImageViewer2 documentation:
>> <http://www.vtk.org/doc/nightly/html/classvtkImageViewer2.html>
>> 
>> "This can be used to annotate an image with a PolyData of "edges" or or
>> highlight sections of an image or display a 3D isosurface with a slice
>> from the volume, etc. Any portions of your geometry that are in front of
>> the displayed slice will be visible; any portions of your geometry that
>> are behind the displayed slice will be obscured."
>> 
>> Does PolyData of "edges" mean that filled polydata won't be displayed
>> properly?
>> 
>> Mathieu
>> 
>> >Hi Mathieu,
>> >
>> >thanks for your quick reply!  
>> >Yes, the polydata are all on the same layer as the image.
>> >I would like to know why the contour lines show since they are
>> >also in the same plane as the image (and the polygon) 
>> >but the polygon will not?  The polygon actor is only
>> >visible when rendered in wireframe mode.
>> >
>> >Dean
>> >
>> >> Subject: Re: [vtkusers] mixing vtkImageActor with solidly rendered
>> >>  vtkPolyData
>> >> 
>> >> Hi,
>> >> 
>> >> Is the polydata on the same layer as the image? I mean,
>> >> if the image origin is (originX, originY, originZ), the
>> >> polydata origin should be closer to the camera in the
>> >> direction of projection to make sure it is always visible.
>> >> Otherwise it may appear or not if they are defined at the same
>> >> position.
>> >> 
>> >> I usually define an epsilon value to the polydata to put in
>> >> front of an image. If my image is at (originX, originZ, 0), I put my
>> >polydata
>> >> position as (posX, posY, epsilon).
>> >> 
>> >> Hope it will help...
>> >> 
>> >> Thanx.
>> >> 
>> >> MAthieu
>> >> 
>> >> --
>> >> > >
>> >> >in a renderer I have a vtkImageActor (ivar of vtkImageViewer2)
>> >> >showing a slice of a 3D image.  On top of that are
>> >> >two vtkActors rendering 2D contours (vtkPolyData lines) from a
>> >> >segmentation and
>> >> >another actor rendering a 2D filled segmentation region (
>> >> >vtkPolyData solid polygon).  When I scroll through the slices,
>> >> >each slice's contour lines and polygonal region are
>> >> >updated.  I can see the lines but the polygons appear
>> >> >briefly and then disappear.  If I hide the vtkImageActor,
>> >> >the polygons are clearly there.  If I set the polygon actor
>> >> >to render as a wireframe, the region is correctly shown as a
>triangulated
>> >> >polygon whether or not the image actor is visible or not.
>> >> >If I toggle between wireframe and solid when the image actor
>> >> >is visible, the solid polygon will not display: only the wireframe
>> >> >representation will.  SetCoincidentTopologyToPolygonOffset has no
>> >> >effect.  How can I mix vtkImageActor with solidly rendered vtkPolyData?
>> >> >
>> >> >Dean
>> >> >
>> >> >_______________________________________________
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>> >> 
>> >> 
>> >> 
>> >> 
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>> 
>> 
>> 
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