Background color always black

Hi, I am using a QQuickVtkRenderWindow inside a bigger software with a smaller QQuickVtkRenderItem. I changed the background color of the QQuickVtkRenderItem no problem… but the QQuickVtkRenderWindow is still black… and is the whole software window. To just change the backgound-color of my application window inside QML code doesn’t work.
Does anyone have any idea how to fix that?

Thanks for your help

Hi, Julien,

I change the background of my scene via renderer (vtkRenderer):

    // add a nice sky-like background
    _rendererMainScene->SetBackground(0.9, 0.9, 1);
    _rendererMainScene->SetBackground2(0.5, 0.5, 1);
    _rendererMainScene->SetLayer( 0 ); //only the renderer of layer 0 have background.



But the renderer take the size of my QQuickVTKRenderItem and not of my QQuickVtkRenderWindow


Well, that’s a different question.

1 Like

I get the same problem.Have you found a good solution for this?

Hi I have the same problem here. Does any one know the solution ?


what version of vtk did you use?

FYI, recently the qml support in VTK has been improved

until the next release of VTK, I recommand you to use vtk master.

after a quick test with vtk master, I can set a background color (blue and green in the screen), so it shiould fix your issue

Hi @lgivord thanks for the reply. I am using VTK 9.2.6 version i think this is pretty recent version.
To me , it seems you change the background of renderer or renderitem.

the problem @Julienchz mentioned here is the background color and size change of the renderwindow.
for example, if the application size is 1000x1000. and the renderwindow is always following the application size and cannot be smaller than that. Also, its background is always black and cannot be changed.

Just wondering if this is an known bug for current VTK version.

for each QQuickVtkRenderWindow->renderWindow->GetRenderers()

or possibly


Are you saying your vktRenderer does not fill the whole vtkRenderWindow? Perhaps you need another dummy vtkRenderer for the empty space.

You’re right, also recent work on qml in vtk isn’t in VTK 9.2.6, but will be available in the next release.

Note that QQuickVtkRenderWindow will be deprecated in VTK 9.3.0 and we should always using instead QQuickVTKItem, so this issue should not be in vtk master.

There is few example in vtk here : to show how using it now.

In short, you will need to create your own class which herited to QQuickVtkItem :

  • the main.cxx
class MyVtkItem : public QQuickVTKItem
  struct Data : vtkObject
    static Data *New();
    vtkTypeMacro(Data, vtkObject);

    vtkNew<vtkActor> actor;
    vtkNew<vtkPolyDataMapper> mapper;

  // -----------------------------------------------------------------------
  vtkUserData initializeVTK(vtkRenderWindow *renderWindow) override
    vtkNew<vtkSphereSource> sphereSource;
    sphereSource->SetCenter(0.0, 0.0, 0.0);


    vtkNew<vtkActor> boxActor;
    vtk->actor->GetProperty()->SetColor(0, 0, 0.5);

    vtkNew<vtkRenderer> renderer;
    vtkNew<vtkNamedColors> colors;


    return vtk;
  vtkNew<Data> vtk;

// -----------------------------------------------------------------------
int main(int argc, char *argv[])
  QGuiApplication app(argc, argv);

  QQmlApplicationEngine engine;
  qmlRegisterType<MyVtkItem>("com.vtk.example", 1, 0, "MyVtkItem");

  if (engine.rootObjects().isEmpty())
    return -1;

  return app.exec();

And in the main.qml file something like that:

import QtQuick 2.9
import QtQuick.Controls 2.12
import QtQuick.Window 2.2
import com.vtk.example 1.0
import QtQuick.Dialogs 1.0

ApplicationWindow {
  id: win
  visible: true
  width: 500
  height: 500
  title: qsTr("vtk-qml-demo")

  MyVtkItem {
    id: vtk
    x: 0
    y: 0
    width: parent.width
    height: parent.height

you will obtain something like that:


I hope this would help you :slightly_smiling_face:

Thanks @lgivord for your response. That’s very helpful.
Is that true that current vtk version does not support QQuickVTKItem standing alone in QML. I am following this sample code for QQuickVTKItem now.

// import related modules
import QtQuick 2.15
import QtQuick.Controls 2.15
import QtQuick.Window 2.15
// import the VTK module
import VTK 9.0
// window containing the application
ApplicationWindow {
  // title of the application
  title: qsTr("VTK QtQuick App")
  width: 400
  height: 400
  color: palette.window
  SystemPalette {
    id: palette
    colorGroup: SystemPalette.Active
  // Instantiate the vtk render window
  VTKRenderWindow {
    id: vtkwindow
    width: 400
    height: 400
  // add one or more vtk render items
  VTKRenderItem {
    objectName: "ConeView"
    x: 200
    y: 200
    width: 200
    height: 200
    // Provide the handle to the render window
    renderWindow: vtkwindow

Looking forward to the realse of v9.3.0

I think yes in 9.2.6 it is not supported