[vtkusers] Render scene without shading, light, interpolation

[Cory Quammen]

Hi,

It seems like you are doing the right things and should expect to get
the color values you set. Could you attach a small image showing the
output you get and maybe highlight a cell that does not have the
expected color? Are the colors way off from what you expect, or just
slightly different?

Thanks,
Cory

On Wed, Nov 30, 2016 at 2:20 AM, Jaehyun Jang <sysexits at gmail.com> wrote:
> Dear vtk users,
>
> I am trying to these tasks using vtkPolyDataMapper with
> vtkUnsignedCharArray, vtkRenderer, vtkRenderWindow to get pixel count of a
> specific cell
>
> 1. Translate index value(within 1 ~ 16777215) to R, G, B value (using R =
> idx & 255, G = (idx >> 8) & 255, B = (idx >> 16) & 255
> 2. From all points of each cell, assigning those color values into
> vtkUnsignedCharArray with SetTupleValue(point index of same cell, color)
> (the forth value of color is always 255)
> - i.e, All different cells have different RGB value. (If I set only 50 cells
> in the model, only 50 cells have distinct color in 1 ~ 50)
> 3. Setting the model using vtkProperty with these settings
>     m_actor->GetProperty()->BackfaceCullingOn();
>     m_actor->GetProperty()->LightingOff();
>     m_actor->GetProperty()->ShadingOff();
>     m_actor->GetProperty()->SetInterpolationToFlat();
>
> 4. Render this model using vtkRenderWindow with these settings
>     renderwindow->SetOffScreenRendering(1);
>     renderwindow->AddRenderer(renderer);
>     renderwindow->SetSize(600, 600);
>     renderwindow->Render()
> 5. Get vtkImageData using vtkWindowToImageFilter and access GetScalarPointer
> 6. Translate RGB to index and count it.
>
> However, RGB values translate wrong indices which I did not expect, I want
> to know how to set my renderer or actor without interpolation and shading to
> get the expected color.
>
> Thanks.
>
> --
> Jaehyun Jang
> Master's candidate
> School of Computing, KAIST
> 291, Daehak-ro, Yuseong-gu, Daejeon
> E3-1, 2413 STE
> Computer Graphics and Visualization Lab
> Resume | Github | Personal
>
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-- 
Cory Quammen
Staff R&D Engineer
Kitware, Inc.