[Bf-committers] Python callbacks and keeping properties in sync

Ton Roosendaal ton at blender.org
Wed Mar 30 16:09:36 CEST 2011

Hi Doug,

I remind Campbell about this regularly, and we've reviewed a couple of  
strategies for it.
The issue is extremely complex though, especially because existing  
code might need to be upgraded to comply to a decent API on python  

In short:
- Data-Data dependencies belong in the dependency graph, handled  
reliably outside UI.
- Data-UI dependencies can be handled on notifier or event levels

- Some UI widgets/menus might maintain data as well, with dependencies
- Our UI is directly using data pointers to write/read, with  

What would be helpful is to first make the minimal list of crucial  
features required for proper handling of exporter/integration scripts.  
I'm still missing the big picture a bit.


Ton Roosendaal  Blender Foundation   ton at blender.org    www.blender.org
Blender Institute   Entrepotdok 57A  1018AD Amsterdam   The Netherlands

On 30 Mar, 2011, at 16:00, Doug Hammond wrote:

> Is anyone going to acknowledge this at all?
> Cheers,
> Doug.
> On 28 March 2011 23:05, Doug Hammond  
> <doughammond at hamsterfight.co.uk> wrote:
>> I've also seen too that there were plans to get this implemented  
>> around
>> about now.
>> (It was suggested in meeting minutes some weeks ago to be done in  
>> March?).
>> Campbell has also admitted that he's got some of the code for it  
>> already
>> written, and
>> it is really about time this became implemented, us python devs  
>> have been
>> waiting
>> forever (it seems).
>> So, any chance to get this before the stable release ?
>> Cheers,
>> Doug.
>> On 28 March 2011 12:55, Wenzel Jakob <wenzel at wazlaf.org> wrote:
>>> Hello all,
>>> I am currently designing a rendering backend that integrates  
>>> Mitsuba (a
>>> physically based renderer) with Blender 2.56a based on Doug  
>>> Hammond's
>>> extensions framework.
>>> One of the issues I am periodically facing is synchronization  
>>> between
>>> the Blender and Mitsuba interpretations of the scene. For instance,
>>> Blender Internal and Mitsuba have wildly different material
>>> configurations, and hence the rendering plugin adds custom UI  
>>> panels to
>>> configure all materials.
>>> However, there is still a bit of overlap with Blender Internal. It  
>>> would
>>> be great if it was possible to "react" to property changes in a  
>>> material
>>> so that they can be forwarded to the other respective material
>>> implementation (where it makes sense). For instance: if the user
>>> specifies a diffuse gray BI material, that could easily be  
>>> replicated in
>>> the Mitsuba material panel.
>>> I remember that somebody was working on Python-based property  
>>> callbacks,
>>> which could potentially be used to implement such a feature. I'm  
>>> curious
>>> to hear about the state of this work.
>>> Thank you,
>>> Wenzel
>>> _______________________________________________
>>> Bf-committers mailing list
>>> Bf-committers at blender.org
>>> http://lists.blender.org/mailman/listinfo/bf-committers
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