dynamic update issues

[vpaeder]

Hello!
I wrote a library that generates toolpaths for some kind of engraving machine and displays them using VTK. I tought to try trame for remote display. Now I do have a little issue with dynamic update. It works with VtkRemoteView (or VtkRemoteLocalView in remote mode), but not with VtkLocalView (or VtkRemoteLocalView in local mode). In local mode, I can trigger the update from client (linked logo click action with view update) but not from server. Is this expected or am I missing something?

I use VTK 9.1.0 and trame from git (pulled June 18) on macos and debian.

Here is a short code to illustrate what I mean:

import asyncio

from trame.ui.vuetify import SinglePageLayout
from trame.widgets import vuetify, vtk
from trame.app import get_server, asynchronous

server = get_server()
state, ctrl = server.state, server.controller

# -----------------------------------------------------------------------------
# VTK pipeline
# -----------------------------------------------------------------------------
from vtkmodules.vtkFiltersSources import vtkConeSource
from vtkmodules.vtkRenderingCore import (
    vtkRenderer,
    vtkRenderWindow,
    vtkRenderWindowInteractor,
    vtkPolyDataMapper,
    vtkActor,
)
from vtkmodules.vtkInteractionStyle import vtkInteractorStyleSwitch  # noqa
import vtkmodules.vtkRenderingOpenGL2  # noqa: necessary for remote rendering

renderer = vtkRenderer()
renderWindow = vtkRenderWindow()
renderWindow.AddRenderer(renderer)

renderWindowInteractor = vtkRenderWindowInteractor()
renderWindowInteractor.SetRenderWindow(renderWindow)
renderWindowInteractor.GetInteractorStyle().SetCurrentStyleToTrackballCamera()

cone_source = vtkConeSource()
mapper = vtkPolyDataMapper()
actor = vtkActor()
mapper.SetInputConnection(cone_source.GetOutputPort())
actor.SetMapper(mapper)
renderer.AddActor(actor)
renderer.ResetCamera()
renderWindow.Render()

# -----------------------------------------------------------------------------
# Background thread
# -----------------------------------------------------------------------------
@asynchronous.task
async def refresh_function(**kwargs):
    res = 0
    while True:
        print("Resolution: {}".format(res+3))
        cone_source.SetResolution(res+3)
        res = (res+1) % 20
        ctrl.flush_content()
        ctrl.view_update()
        await asyncio.sleep(0.5)

# -----------------------------------------------------------------------------
# Web App setup
# -----------------------------------------------------------------------------
with SinglePageLayout(server) as layout:
    layout.icon.click = ctrl.view_update # click on logo to force update
    with layout.content:
        # content components
        with vuetify.VContainer(
            fluid=True,
            classes="pa-0 fill-height",
        ):
            # dynamic update works in remote view but not in local view
            view = vtk.VtkLocalView(renderWindow, namespace="view")
            #view = vtk.VtkRemoteView(renderWindow, namespace="view")
            #view = vtk.VtkRemoteLocalView(renderWindow, namespace="view", mode="local")
            ctrl.view_update = view.update
            ctrl.on_server_ready.add(view.update)
            ctrl.on_server_ready.add(refresh_function)
    
    ctrl.flush_content = layout.flush_content


server.start()

[jourdain]

@asynchronous.task
async def refresh_function(**kwargs):
    res = 0
    while True:
        with state:
           print("Resolution: {}".format(res+3))
           cone_source.SetResolution(res+3)
           res = (res+1) % 20
           ctrl.view_update()
        await asyncio.sleep(0.5)

[jourdain]

The deal with async function is that the state is not going to flush automatically, so you either have to call state.flush() yourself or use the state context manager which does that on exit.

[vpaeder]

Great! thanks a lot, this works fine that way.