[vtk-developers] Why two scalar volume rendering failed???

[Enya Shen]

Hi all,

I tried to use different scalar for color and opacity in volume rendering
as follows. But it failed to use the second scalar to get opacity. Why?
Thank you for any advice!!!

......

vtkPiecewiseFunction* opacityFn = vtkPiecewiseFunction::New();

vtkColorTransferFunction* colorFn = vtkColorTransferFunction::New();


vtkVolumeProperty* volumeProperty = vtkVolumeProperty::New();

volumeProperty->SetIndependentComponents(false);

volumeProperty->SetScalarOpacity(this->opacityFn);

volumeProperty->SetColor(this->colorFn);

volumeProperty->SetInterpolationTypeToLinear();

volumeProperty->ShadeOn();


vtkVolume* volumeActor = vtkVolume::New();

volumeActor->SetProperty(this->volumeProperty);


colorFn->AddRGBPoint(this->scalarsRange[0][0], 0.0, 0.0, 1.0);

colorFn->AddRGBPoint(0.5*(this->scalarsRange[0][0]+this->scalarsRange[0][1]),
0.0, 1.0, 0.0);

colorFn->AddRGBPoint(this->scalarsRange[0][1], 1.0, 0.0, 0.0);

opacityFn->AddPoint(this->scalarsRange[1][0], 0.0, 0.0, 0.0);

opacityFn->AddPoint(0.5*(this->scalarsRange[1][0]+this->scalarsRange[1][1]),
0.5, 0.0, 0.0);

opacityFn->AddPoint(this->scalarsRange[1][1], 1.0, 0.0, 0.0);

volumeProperty->SetIndependentComponents(true);

......


Regards,

Enya
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