[vtkusers] Opacity and vtkColorTransferFunction

[Wen-Hsing Chiang]

Hi,
I am getting a problem in making an actor translucent. The color of the
actor is mapped to the scalar values by vtkColorTransferFunction. I
tried to set a rather small opacity value (0.1) to the actor, but it
remains opaque. The problem does not occur when using vtkLookupTable.
Since I need to map particular values to designated colors,
vtkLookupTable is not suitable.

Here is the suedo code, can anyone tell me what is wrong? Thanks! 

vtkPolyData * pPolyData = vtkPolyData::New()
//set up pPolyData here....

vtkColorTransferFunction * pColorTransferFunction =
vtkColorTransferFunction::New();
for (int i = 0; i < m_iNumberOfColors; i++)	
{
    pColorTransferFunction->AddRGBPoint(value[i], red[i], green[i],
blue[i]);
}
// pColorTransferFunction->SetAlpha(0.1) does not work also!!

vtkPolyDataMapper * pPolyDataMapper	= vtkPolyDataMapper::New();
pPolyDataMapper->SetInput(pPolyData);
pPolyDataMapper->SetLookupTable(pColorTransferFunction);

vtkActor * pActor = vtkActor::New();
pActor->SetMapper(pPolyDataMapper);	
pActor->GetProperty()->SetOpacity(.1); 
......



Wen-Hsing Chiang, Ph.D.
Integrated Environmental Services, Inc.
20 Fairbanks, Suite 187
Irvine, CA 92618
USA
tel. 949.460.7003
fax. 949 460 7019

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