[Development] Many congratulations and one question

Sean Harmer sean.harmer at kdab.com
Sun Jun 19 10:55:54 CEST 2016

Hi Massimo,

On 18/06/2016 15:41, Massimo Callegari via Development wrote:
> Hi everyone,
> today, instead of being the usual "complaining guy" I'd like to explicit my biggest congratulations and gratitude to all the people behind the Qt3D module.
> In particular to Sean Harmer and Paul Lemire at KDAB, who have been doing a monumental job working during weekends, fighting against CI breakage and taking care of an infinite number of JIRA issues and reports.
> I've been following the Qt3D developments for a couple of years and I have to say Qt3D is going to be an awesome addition to the Qt features set.
> I tried as much as I could to support the developments by testing patches and reporting issues and I hope I've been somehow helpful for the project.

Thank you for your kind words. Yes, please do keep the bug reports 
coming and prodding us when needed.

> I'm also very excited by the Qt3D editor and I'd like to congratulate with all the Qt people behind it as well.
> Even if it's in a very early stage, you can already feel it is going to be an awesome tool !

+1. It's already shaping up to be a nice addition. I hope it can 
continue to be extended and hopefully one day become a great plugin for 
Qt Creator

> So, well done everybody !

Thank you and I'd like to echo my own thanks to everybody who has helped 
with code, reporting bugs, asking questions that pushed us to make sure 
Qt 3D is flexible enough to work with as many rendering algorithms as 
possible. I already have plenty of ideas on how to continue extending 
the frame graph in 5.8 and beyond plus a whole bunch of other additions 
that we discussed with Pasi and his team in Oulu recently.

> Now I've got a question for the Qt3D guys who knows all the techy bits of the current status of the module.
> It is my intention to implement the technique described in these AMD slides:
> https://developer.amd.com/wordpress/media/2012/10/Mitchell_LightShafts.pdf
> I am wondering if Qt3D can already cover such usage or if there are missing bits that are still not there or not planned at all.

I don't see anything in there that Qt 3D can't do with a suitable 

> A plus for my project is if that technique can work in a deferred rendering pipeline.

That technique relies upon alpha blended, view-aligned quads. It would 
need to be applied after the deferred portion of the rendering as alpha 
blending doesn't play nicely with deferred. So something like this might 
be something to try:

1) G-buffer pass
2) Lighting pass of opaque geometry
3) Light shafts pass for the brightest n lights, where n is tuned to 
what your hardware can handle.

Depending upon the scene you want to render you may be able to hand 
select which lights trigger light shafts. For example, if you have 10 
bright spot lights, use those with light shafts and just rely upon some 
other post-processing effect like bloom for the dimmer lights or point 
lights which can be done in a single post-proc pass.

> If KDAB/Qt is interested in such usage case, I am more than willing to contribute to the developments or even support a developer more skilled than me in the 3D area with a monetary contribution.

Sounds like an interesting algorithm to implement. If you'd like to do 
it on a commercial basis then feel free to contact us.

Have a nice weekend and thank you again for your kind words and help!


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

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