[vtkusers] VS: ÄvtkusersÅ Polydata + translucent volume

Hämäläinen Janne Janne.Hamalainen at hus.fi
Tue Jul 29 02:54:33 EDT 2003


	>Does your cursor have an opacity less than 1.0? If so, it will not
work 
	>correctly.

No it doesn't, the opacity hasn't been changed. Actually, I noticed that
setting clipping range using vtkRenderer's ResetCameraClippingRange( float
bounds[6] ) -method before rendering the scene for some reason fixes the
problem. Does someone know why? Doesn't the camera get any default values
for clipping planes, and does the rendering process get messed up if no
values are set?

-Janne



> At 08:11 AM 7/25/2003, Hämäläinen Janne wrote:
> >Hi all,
> >
> >I'm rendering 3D volume using predefined vtkColorTransferFunction and
> scalar
> >opacity function, and trying to render a 3D cursor (vtkCursor3D) into the
> >same scene. Problem is that although the focal point of the cursor should
> be
> >inside the visible part of the volume, it is rendered so that it is
> appears
> >to be outside the volume, i.e., so that there is no translucent volume
> >hiding it ( the cursor is the closest object to camera from view points
> ).
> >I've understood that there could be sometimes problems in ordering
> polydata
> >if there is objects in scene that has opacity less than 1. I've tried to
> >order actors in the renderer as was suggested in the vtk handbook (
> volume
> >first and cursor last )  and also tried vtkDepthSortPolyData ( although
> >didn't understand how it works ), but nothing has helped. If someone has
> >knowledge on what I should do, please let me know.
> >
> >Cheers, Janne
> >
> >
> >
> >--
> >Janne Hämäläinen
> >Research Assistant
> >Helsinki University Central Hospital
> >X-ray Department
> >
> >email   janne.hamalainen at hus.fi
> >
> >
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