Merge pull request #2255 from psavery/gradient-opacity-multivolume-only

Force gradient opacity for multi-volumes only

Author: cjh1

tomviz/modules/ModuleVolume.cxx

@@ -62,6 +62,7 @@ vtkStandardNewMacro(SmartVolumeMapper)
 {
   // NOTE: Due to a bug in vtkMultiVolume, a gradient opacity function must be
   // set or the shader will fail to compile.
+  // (likely fixed in https://gitlab.kitware.com/vtk/vtk/-/merge_requests/8909)
   m_gradientOpacity->AddPoint(0.0, 1.0);
   connect(&HistogramManager::instance(), &HistogramManager::histogram2DReady,
           this, [=](vtkSmartPointer<vtkImageData> image,
@@ -81,6 +82,12 @@ vtkStandardNewMacro(SmartVolumeMapper)
             this->updateColorMap();
             emit this->renderNeeded();
           });
+
+  // NOTE: Due to a bug in vtkMultiVolume, a gradient opacity function must
+  // be set or the shader will fail to compile.
+  // (likely fixed in https://gitlab.kitware.com/vtk/vtk/-/merge_requests/8909)
+  connect(&VolumeManager::instance(), &VolumeManager::usingMultiVolumeChanged,
+          this, &ModuleVolume::updateColorMap);
 }
 
 ModuleVolume::~ModuleVolume()
@@ -371,9 +378,20 @@ void ModuleVolume::updateColorMap()
   int propertyMode = vtkVolumeProperty::TF_1D;
   const Module::TransferMode mode = getTransferMode();
   switch (mode) {
-    case (Module::SCALAR):
-      m_volumeProperty->SetGradientOpacity(m_gradientOpacity);
+    case (Module::SCALAR): {
+      // NOTE: Due to a bug in vtkMultiVolume, a gradient opacity function must
+      // be set or the shader will fail to compile.
+      // (likely fixed in
+      // https://gitlab.kitware.com/vtk/vtk/-/merge_requests/8909)
+      bool usingMultiVolume =
+        VolumeManager::instance().usingMultiVolume(this->view());
+      if (usingMultiVolume) {
+        m_volumeProperty->SetGradientOpacity(m_gradientOpacity);
+      } else {
+        m_volumeProperty->SetGradientOpacity(nullptr);
+      }
       break;
+    }
     case (Module::GRADIENT_1D):
       m_volumeProperty->SetGradientOpacity(gradientOpacityMap());
       break;

tomviz/modules/VolumeManager.cxx

@@ -90,6 +90,8 @@ void VolumeManager::onModuleAdded(Module* module)
       viewVolumes->auxProperty->SetScalarOpacity(viewVolumes->auxOpacity);
       // NOTE: Due to a bug in vtkMultiVolume, a gradient opacity function must
       // be set or the shader will fail to compile.
+      // (likely fixed in
+      // https://gitlab.kitware.com/vtk/vtk/-/merge_requests/8909)
       viewVolumes->auxProperty->SetGradientOpacity(
         viewVolumes->auxGradientOpacity);
       viewVolumes->auxVolume->SetProperty(viewVolumes->auxProperty);
@@ -243,6 +245,15 @@ bool VolumeManager::allowMultiVolume(vtkSMViewProxy* view) const
   return this->d->views[view]->usingMultiVolume;
 }
 
+bool VolumeManager::usingMultiVolume(vtkSMViewProxy* view) const
+{
+  if (!this->d->views.contains(view)) {
+    return false;
+  }
+
+  return this->d->views[view]->usingMultiVolume;
+}
+
 int VolumeManager::volumeCount(vtkSMViewProxy* view) const
 {
   if (!this->d->views.contains(view)) {

tomviz/modules/VolumeManager.h

@@ -30,6 +30,7 @@ class VolumeManager : public QObject
   static VolumeManager& instance();
   void allowMultiVolume(bool allow, vtkSMViewProxy* view);
   bool allowMultiVolume(vtkSMViewProxy* view) const;
+  bool usingMultiVolume(vtkSMViewProxy* view) const;
   int volumeCount(vtkSMViewProxy* view) const;
 
 signals: