How to check if rendering is done/ready

Is there a way to check if rendering is done/ready (vtkRenderer & vtkRenderWindow)? I’m calling Render very frequently, and the GPU basically falls behind a bit which introduces a lag. What I’d like to do is have an if statement before my Render call, so that it only gets called if it’s ready to Render. Thanks!


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If you’re working in Python, you could try to overwrite the Render call to keep track of the status:

import vtk

class MyRenderWindow(vtk.vtkRenderWindow):
    def __init__(self, **args):
        super(MyRenderWindow, self).__init__(**args)
        self._is_ready = True

    def is_ready(self):
        return self._is_ready

    def Render(self, **args):
        self._is_ready = False
        vtk.vtkRenderWindow.Render(self, **args)
        self._is_ready = True

Then use it like:

ren_win = MyRenderWindow()
if ren_win.is_ready:

Unless I’m not understanding something, wouldn’t this just tell me when the Render call has happened? What I need to know is when the GPU is actually done with the Render (which can take longer than the Render call). The Render call sends instructions/requests to the GPU, and then the GPU handles them as fast as it can. But it can easily fall behind if you’re calling Render very frequently. So what I need is a way to know if the GPU is done with the previous Render call.