[vtkusers] Mappers and vtkLookupTable

Allen Sanderson allen at sci.utah.edu
Tue Feb 16 17:32:39 EST 2016


Thanks David, we thought that was the case. 

Let me ask a somewhat parallel question. When rendering lines one typically sets a line width and sends the geometry downstream. The lines will be colored base on a variable but the line width is constant. At the same time when doing point glyphs we set the color and size based on a variable. If we wanted to vary the line width using a variable is our only choice to use a cylinder?

Cheers,

Allen


Allen Sanderson
SCI Institute
University of Utah
www.sci.utah.edu



> On Feb 16, 2016, at 12:20 PM, David Gobbi <david.gobbi at gmail.com> wrote:
> 
> Hi Allen,
> 
> You are correct, vtkLookupTable does not provide a way of doing this.
> 
> I'm not sure what work-arounds there are for geometry, but for images
> you can map the RGB and A separately, and then combine them into
> RGBA with vtkImageAppendComponents.
> 
>  - David
> 
> 
> On Tue, Feb 16, 2016 at 11:48 AM, Allen Sanderson <allen at sci.utah.edu <mailto:allen at sci.utah.edu>> wrote:
> Hello,
> 
> We are trying to render geometry using a lookup table for the RGB value using one scalar variable, but we want to use a secondary scalar variable for determining the opacity.  Something like the following:
> 
> RGB -> variable one
> A -> variable two
> 
> In looking through the VTK 6 documentation on mappers we have not found anything that leads us to believe this functionality is possible. But we have done an exhaustive search.
> 
> If it is possible we would greatly appreciate pointers. Thanks.
> 
> 
> 
> Cheers,
> 
> Allen
> 
> 
> Allen Sanderson
> SCI Institute
> University of Utah
> www.sci.utah.edu <http://www.sci.utah.edu/>
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