The vtkActor show in multi renderwindow problem

Support
1

There are two vtkRenderWindow objects, each with two vtkRenderer objects, and the layers have been set. The vtkActor is initially set to the lower-level vtkRenderer of each vtkRenderWindow, and it displays normally.

Now, after changing the color and opacity of the vtkActor, if remove it from the lower-level renderer of each window and add it to the higher-level renderer, the vtkActor will only display correctly in the first rendered window. In the second rendered window, the vtkActor disappears.

void MoveActorToTop(vtkSmartPointer<vtkProp> actor)
 {
        if (leftWin_ != nullptr)
        {
            leftWin_ ->loewerRenderer_->RemoveActor(actor);
        }

        if (rightWin_ != nullptr)
        {
            rightWin_ ->loewerRenderer_->RemoveActor(actor);
        }

        if (leftWin_ != nullptr)
        {
            leftWin_ ->upperRenderer_->AddActor(actor);
        }
    
        if (rightWin_ != nullptr)
        {
            rightWin_ ->upperRenderer_->AddActor(actor);
        }
    }

After:
left window:

image
image735×680 5.72 KB

right window:
image
image633×550 4.39 KB

2

Hello @nanoahSR

Is lowerRenderer assigned to layer=0, and is upperRenderer assigned to layer=1? That should work. Can you confirm in your code whether the window has both the renderers?

3

This may also help: TransparentBackground. Not the same but may be useful.

4

Hi @jaswantp
Here is my code:

        lowerRender_ = vtkSmartPointer<vtkRenderer>::New();
        lowerRender_ ->SetGradientBackground(true);
        lowerRender_ ->SetLayer(0);

        upperRender_ = vtkSmartPointer<vtkRenderer>::New();
        upperRender_ ->SetGradientBackground(true);
        upperRender_ ->SetLayer(1);
        // Set same camera as default render
        upperRender_ ->SetActiveCamera(lowerRender_->GetActiveCamera());

        renderWindow_->SetNumberOfLayers(2);
        renderWindow_->AddRenderer(lowerRender_);
        renderWindow_->AddRenderer(upperRender_ );

When I only have a vtkRenderWindow, the display is fine

5

Can you turn off gradient background to see if that works?

6

FYI, this example may give you some ideas: MultipleLayersAndWindows. There seem to be no issues with multiple actors and windows. In this example, we have two windows each with with two layers and a single actor in each window.

Run the interactive example to see how it looks.

Note:

  • The layer 0 background is the only visible background, backgrounds in layer 1 and subsequent layers are transparent.
  • It is easy to access the renderers and actors from the interactor by iterating through the renderer and actor collections.
  • In renderer collections and actor collections it is important to remember that the references are stored in last in - first out order.