[Interest] [Qt3D] Best way to do operations before rendering

Sean Harmer sean.harmer at kdab.com
Mon Oct 3 09:21:24 CEST 2016


Hi,

a QFrameAction is for code that should be executed once per frame not a 
one time thing. It's mainly useful for prototyping as it can be quite 
expensive due the backend/frontend synchronisation it entails.

To have some operation completed before rendering a part of your scene 
graph, just defer adding that subtree to the scene graph until it is 
done. That is, call your function that builds your uber shader then when 
that is done add your sub-tree that uses that shader to the main scene 
graph.

Cheers,

Sean

On 02/10/2016 22:22, Xavier Bigand wrote:
> I have some operations that I need to do before the scene-graph start
> the rendering or a least be able to do an operation before a specific
> node is rendered.
>
> I want to start by building the source code of the uber-shader used by
> my custom material. So I tried to use a QFrameAction on my root scene
> node, but the slot isn't called.
> I have attached the QFrameAction as component of root node and then
> connect my slot to it, but the slot is never called.
>
> My I missed something, or it is simply not the good way to do?
>
>
> --
> Xavier
>
>
> _______________________________________________
> Interest mailing list
> Interest at qt-project.org
> http://lists.qt-project.org/mailman/listinfo/interest
>

-- 
Dr Sean Harmer | sean.harmer at kdab.com | Managing Director UK
KDAB (UK) Ltd, a KDAB Group company
Tel. +44 (0)1625 809908; Sweden (HQ) +46-563-540090
Mobile: +44 (0)7545 140604
KDAB - Qt Experts



More information about the Interest mailing list