BUG: Hide volume rendering color transfer function if using direct co…

…lor mapping

When rendering RGB or RGBA volumes are rendered (using IndependentComponents volume rendering property set to false) then the color is read directly from the voxel's RGB value. In this case color transfer function is ignored.

To avoid user confusion by being able to adjust the color transfer function that has no effect, the color transfer function section is not displayed if IndependentComponents=false.

Libs/Visualization/VTK/Widgets/ctkVTKVolumePropertyWidget.cpp

@@ -218,6 +218,7 @@ void ctkVTKVolumePropertyWidget::updateFromVolumeProperty()
   vtkColorTransferFunction* colorTransferFunction = 0;
   vtkPiecewiseFunction* opacityFunction = 0;
   vtkPiecewiseFunction* gradientFunction = 0;
+  bool scalarColorMapping = true;
   if (d->VolumeProperty)
     {
     colorTransferFunction =
@@ -229,6 +230,7 @@ void ctkVTKVolumePropertyWidget::updateFromVolumeProperty()
     gradientFunction =
       d->VolumeProperty->GetGradientOpacity()->GetSize() ?
       d->VolumeProperty->GetGradientOpacity() : 0;
+    scalarColorMapping = d->VolumeProperty->GetIndependentComponents();
     }
 
   d->ScalarOpacityThresholdWidget->setPiecewiseFunction(
@@ -254,6 +256,10 @@ void ctkVTKVolumePropertyWidget::updateFromVolumeProperty()
   d->ScalarColorWidget->view()->setColorTransferFunctionToPlots(colorTransferFunction);
   d->GradientWidget->view()->setPiecewiseFunctionToPlots(gradientFunction);
 
+  // If color is specified by dependent components (RGBA volume) then do not show scalar color transfer
+  // function, because that function has no effect.
+  d->ScalarColorGroupBox->setVisible(scalarColorMapping);
+
   if (d->VolumeProperty)
     {
     d->InterpolationComboBox->setCurrentIndex(