[Interest] Render QQuickRenderControl render target texture into a QuickItem in the visible QQuickWindow

[Frank Mertens]

Hey Nuno,

done a lot of QQuickRenderControl tricks lately. But I'm using it on QSGRendererInterface::Software.
I'm not sure if it helps, but check out: https://stackoverflow.com/questions/17146747/capture-qml-drawing-buffer-without-displaying/67187802#67187802

God speed,
Frank

On 29.06.21 17:27, Nuno Santos wrote:
> Hi,
>
> I’m trying to make a offscreen renderer for a quick scene and then display it’s output in the main and visible QQuickWindow scene.
>
> The reason I’m trying to achieve this is because I need to intercept the frames to be able to send them to other programs or encode as a video file.
>
> I’ve based myself on the rendercontrol example and I have a working offscreen renderer. Now, what I’m trying to do is to paint the result of the offscreen renderer into the main QQuickWindow.
>
> What I’m doing is creating a new QQuickItem that paints a texture. When I declare this item in qml, I register it on the render control. Render control has it’s own render timing. Whenever render control paints, I tell the registered quick item to paint with the fbo texture.
>
> The problem is that the only thing that is painted is black. I’m pretty sure the quick item is paint texture correctly because it works with images:
>
> // render method
>
> …
>
> if(_renderView)
> {
> _renderView->setImage(_fbo->toImage()); // this works
> _renderView->setTexture(_quickWindow->createTextureFromId(_fbo->texture(),_size)); // this doesn’t work - only black is painted
> }
>
> … 
>
> I wonder if I’m stumbling on synchronisation issues. Maybe when its time for the main window to paint again, that texture is not valid anymore. 
>
> Performance is a key factor in this architecture. I need the fastest solution possible and it doesn’t seem that creating a QImage from a texture and then convert it to QSGTexture is the most performant solution possible.
>
> Has anyone been here before? 
>
> Any advise on how to overcome this problem?
>
> Thanks!
>
> Best regards,
>
> Nuno
>
> _______________________________________________
> Interest mailing list
> Interest at qt-project.org
> https://lists.qt-project.org/listinfo/interest

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.qt-project.org/pipermail/interest/attachments/20210707/2292c54e/attachment.html>