Why rendering is slow in GenericRenderWindow if we re-use it

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1

In my application I did two tests to prouve what I’m saying:

1 case:
In each time I want to render a new 3D surface actor, I delete the whole vtkGenericRenderWindow and the previous actor / mapper, and I re-create a new ones, doing this the rendering is good but I’m risking to have Too many open WebGL contexts warning.

2 case:
In each time I want to render a new 3D surface actor, I re-use the same vtkGenericRenderWindow and I delete the previous actor/ mapper and I create new actor/ mapper, doing this the rendering is slow, so when I move the 3D surface with the mouse it is moving so slow.

2

The second case shouldn’t necessarily be slow, unless your data is very, very large. You typically never want to do #1.

3

Thank you for your answer,
Yes I can say that my data is very large, each polydata (used by the 3D surface actors) size is 30MB and I have 33 patients,

[video-to-gif output image]

This how I’m doing it in my code:

PS: context.current[3].GLWindow is the reference holding my GenericRenderWindow

const brainRender = async () => {
    
    if (context.current[3]) {
        const { actor, mapper, } = context.current[3];
          
        context.current[3].GLWindow.getRenderer().removeAllActors();
  
        if(actor){
          actor.delete()
        }
        if(mapper){
          mapper.delete()
        }
      }
    
    let pd, GLWindow, actor, mapper;
    mapper = vtkMapper.newInstance();
    actor = vtkActor.newInstance();
    GLWindow = context.current[3].GLWindow;

    const reader1 = vtkPolyDataReader.newInstance();
    await reader1
    .setUrl(path)
    .then(async () => {
        pd = reader1.getOutputData();
    })
    .catch((error) => {
        console.log(error);
    });

    const originBrain = origin.current;

    actor.setMapper(mapper);
    actor.setPosition(originBrain[0], originBrain[1], originBrain[2]);

    mapper.setInputData(pd);
    GLWindow.getRenderer().addActor(actor);
    GLWindow.getRenderer().resetCamera();
    GLWindow.getRenderer().getActiveCamera().zoom(1.3);
    GLWindow.getRenderer().getActiveCamera().pitch(2.3);
    GLWindow.getRenderWindow().render();

    const obj = {
      actor: actor,
      mapper: mapper,
      GLWindow: GLWindow,
      pd: pd,
    };

    context.current[3] = { ...obj };
  };

Doing it like this and after displaying 3 or 4 patients, manipulating the 3D surface with the mouse becomes so slow:

[video-to-gif output image]

4

Can you make a devtools performance profile of the slow 3D surface manipulation? I don’t suppose that you have all 33 polydatas visible in the scene, since it just looks like one. But it shouldn’t be that slow.

5

Thank you for your answer, I found the problem,

In each time I’m calling my onClick event I initialize the GLWindow variable with new vtkGenericRenderWindow

let GLWindow =  vtkGenericRenderWindow.newInstance();
if (context.current){
GLWindow = context.current[3].GLWindow
}
//...

So I just removed the initialisation and it works fine!

let GLWindow;
if (context.current){
GLWindow = context.current[3].GLWindow
}
//...