I am working with two actors in a 3D scene, where I need one actor (highlightActor) to always appear on top of another actor (currentActor), even when they are in close proximity or overlapping. Currently, I’m facing Z-fighting issues in certain views, where the two actors seem to compete for visibility, especially when viewed from different camera angles.
I have tried using the following approaches to resolve the issue:
While this works in some views, it doesn’t entirely solve the problem as the highlightActor sometimes still appears behind the other actor, depending on the camera angle.
Like this:
I would like to know if there is a more reliable method in VTK to ensure that one actor always renders on top of another, regardless of camera angle or geometry.
You can try adding a second renderer to your render window:
_rendererMainScene = vtkSmartPointer<vtkRenderer>::New();
(...)
_rendererForeground = vtkSmartPointer<vtkRenderer>::New();
// Foreground renderer will use the same camera of the main renderer
_rendererForeground->SetActiveCamera( _rendererMainScene->GetActiveCamera() );
/* Renderers assigned to layers greater than zero have no background and
are rendered last. */
_rendererForeground->SetLayer( 1 );
(...)
_vtkwidget->renderWindow()->AddRenderer(_rendererMainScene);
_vtkwidget->renderWindow()->AddRenderer(_rendererForeground);
This way, actors added to _renderedForeground will always be on top of those added to _rendererMainScene.
Thanks a lot for your suggestion — adding a second renderer with different layers is a clever idea.
However, I’d prefer not to set up separate interactors for each renderer. My goal is to maintain a single interactor for user input handling, as managing multiple interactors complicates the interaction logic in my application. What I actually want to do is to make sure that the two actors do not interfere with each other:
