[vtkusers] Transparent vtkRenderer with Qt

[Francois Bertel]

Hello Guillaume,

First you need a renderwindow with some alpha (this is false by default):

vtkRenderWindow *renWin = vtkRenderWindow::New();
renWin->SetAlphaBitPlanes(1);

There is no API to set a specific opacity on the background color,
however, the hardcoded alpha value is 0 (this actual code is in
VTK/Rendering/vtkOpenGLRenderer::Clear() ), if your use case is to
have a fully transparent background.

Still in the case of a fully transparent background, the other way to
set it, is to assign the layer of the renderer to be a value greater
than 1. By default it is 0, a value greater than 1 will set the
renderer on an overlay. (see vtkRenderer::SetLayer() )



On Wed, Apr 28, 2010 at 8:21 AM, Guillaume DARDENNE
<guillaume.dardenne at telecom-bretagne.eu> wrote:
> Dear Vtk users,
>
>
>
> I insert a vtk widget in a Qt widget with the QVtkWidget class.
>
> I would like to make the vtkWidget transparent.
>
> I know that it’s possible to set the backward color with the
> setRendererBackground(double, double, double) function but is it possible to
> set also the opacity of this renderer window ?
>
>
>
> Thank you very much for your answers.
>
>
>
> Guillaume
>
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François Bertel, PhD  | Kitware Inc. Suite 204
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