MantisBT - VTK
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0002741VTK(No Category)public2006-01-19 15:302016-08-12 09:54
Jeff Lee 
Kitware Robot 
highmajoralways
closedmoved 
 
 
0002741: offscreen rendering images dim on win32
captured images from a vtkWin32OpenGLRenderWindow offscreen context are dimmer than their onscreen counterparts. this seems to happen only when the user adds lights to the scene. Some initial scanning of the mailing lists give
http://public.kitware.com/pipermail/vtkusers/2003-March/066054.htm [^]
and also
http://public.kitware.com/pipermail/vtkusers/2003-April/066928.html [^]
as hints.
No tags attached.
Issue History
2008-11-30 09:14Mathieu MalaterreAssigned ToMathieu Malaterre => François Bertel
2010-09-07 13:46François BertelAssigned ToFrançois Bertel =>
2011-06-16 13:11Zack GalbreathCategory => (No Category)
2016-08-12 09:54Kitware RobotNote Added: 0036819
2016-08-12 09:54Kitware RobotStatusexpired => closed
2016-08-12 09:54Kitware RobotResolutionopen => moved
2016-08-12 09:54Kitware RobotAssigned To => Kitware Robot

Notes
(0003976)
Mathieu Malaterre   
2006-04-06 17:09   
copying comments from 2nd url

I've also struck the problem of images rendering fine on-screen
but losing their user-defined lighting when rendered off-screen.
e.g. into the clipboard. One place damage may occur is here:
 
void vtkOpenGLRenderer::DeviceRender(void)
{
  this->RenderWindow->MakeCurrent();
  this->ClearLights(); <--- clears all lights!
  this->UpdateCamera();
  this->UpdateLightGeometry();
  this->UpdateLights(); <--- not properly restored?
  glMatrixMode(GL_MODELVIEW);
  this->UpdateGeometry();
  glMatrixMode(GL_MODELVIEW);
  glPopMatrix();
}
 
If no user-defined lights are active, then UpdateLights() adds
a headlight and at least there is some light in the image. But
(guessing here) if we have added a custom set of lights, then
these are lost in the call to ClearLights(); but not restored
in UpdateLights(). And since there is a "non-zero" number of
lights, the default headlight is not added, and scene is dark.
 
My (solution :-) when making movies, is to turn off light-kits
or other user-defined lights, and adjust the scene to be visible
with just the default headlight (which is better than nothing).
If I get time, I plan to build a debug Vtk and trace this.
(0036819)
Kitware Robot   
2016-08-12 09:54   
Resolving issue as `moved`.

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