[vtkusers] Combined surface + wireframe view

[Josh Snyder]

I've taken the same approach (seperate actors and mappers for edges and 
geometry), but with a polydata with many polygons, the addition of the 
second mapper and actor for edges produces a very noticeable slow down. 
I don't know a lot about what's going on behind the scenes, but it seems 
like this would be doing two rendering passes for one geometry. Is this 
necessary at the OpenGL level, or is there a way of getting both eges 
and faces without additional overhead? In other words, if 
EdgeVisibilityOn were to be implemented in VTK, would it only affect how 
we construct our pipelines, or would it be possible to get a performance 
benefit as well?

Thanks,

Josh

Malcolm Drummond wrote:

>Hi John
>
>It's static, so applies to all your mappers - they in turn pass on
>parameters to OpenGL etc. that determine how lines should be made to appear
>on top of polygons.
>
>HTH
>Malcolm
>
>----- Original Message -----
>From: "John Platt" <jcplatt at lineone.net>
>To: <vtkusers at vtk.org>
>Sent: Tuesday, January 13, 2004 12:09 AM
>Subject: FW: [vtkusers] Combined surface + wireframe view
>
>
>  
>
>>Hi Malcolm,
>>
>>I didn't use the 2 actor approach because different mappers are used for
>>each actor and I wasn't sure which mapper should be used to resolve the
>>coincident topology or even if it would work at all. Either mapper seems
>>to work OK. Do you know if this is a happy coincidence?
>>
>>Many thanks.
>>
>>John
>>
>>-----Original Message-----
>>From: Malcolm Drummond [mailto:malcolm at geovision.co.za]
>>Sent: 12 January 2004 14:13
>>To: John Platt
>>Subject: Re: [vtkusers] Combined surface + wireframe view
>>
>>Hi John
>>
>>I think you could just use separate actors for edges and geometry, so
>>you
>>don't have to worry about setting up scalar values etc.
>>
>>Malcolm
>>
>>----- Original Message -----
>>From: "John Platt" <jcplatt at lineone.net>
>>To: <vtkusers at vtk.org>
>>Sent: Saturday, January 10, 2004 12:56 AM
>>Subject: FW: [vtkusers] Combined surface + wireframe view
>>
>>
>>Hi Malcolm,
>>
>>That did the trick - thanks.
>>
>>To achieve the combined view I am using vtkAppendPolyData with 2 inputs
>>
>>        vtkUnstructuredGrid->vtkGeometryFilter  -------------  1
>>                                    |
>>                                    |------ vtkFeatureEdges -- 2
>>
>>changing the cell scalar attribute data in vtkFeatureEdges before it is
>>connected to vtkAppendPolyData to get the required edge colour. Is there
>>an easier route?
>>
>>By setting the actor colour the same as the background, I was hoping to
>>get the effect of a "hidden" wire frame. It would be very useful to have
>>a vtkProperty::SetLineColor() to avoid messing with the scalar
>>attributes to get the colours through a LUT (EdgeVisibility would be
>>better still).
>>
>>Thanks again.
>>
>>John Platt
>>
>>
>>
>>
>>
>>-----Original Message-----
>>From: vtkusers-admin at vtk.org [mailto:vtkusers-admin at vtk.org] On Behalf
>>Of Malcolm Drummond
>>Sent: 08 January 2004 22:20
>>To: vtkusers
>>Subject: Re: [vtkusers] Combined surface + wireframe view
>>
>>Hi John
>>
>>Have a look at the static vtkMapper method SetResolveCoincidentTopology
>>
>>HTH
>>Malcolm
>>----- Original Message -----
>>From: John Platt
>>To: vtkusers at vtk.org
>>Sent: Thursday, January 08, 2004 11:55 PM
>>Subject: [vtkusers] Combined surface + wireframe view
>>
>>Hi vtkUsers,
>>
>>I would like to display both cell edges and coloured cell faces using
>>the same vtkDataSetMapper (surface + wireframe combined).
>>EdgeVisibilityOn() looked like the solution but it does not appear to
>>have been implemented for vtkOpenGLPolyDataMapper.
>>
>>I tried using two superimposed actors with surface and wireframe
>>representation set in the mappers but the cell edges were broken by the
>>cell face colour. One solution may be to slightly inflate the wireframe.
>>
>>Has anybody managed to achieve this effect or tried to implement
>>EdgeVisibilityOn()?
>>
>>Any suggestions would be greatly appreciated.
>>
>>John Platt
>>
>>
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