[Bf-cycles] realtime preview

[Nathan Letwory]

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On 12/11/2015 14:58, Mohamed Sakr wrote:
> Hi Nathan,
> 
> thanks a lot! :) there are 2 things that I need to understand: 1-
> if I change the scene data "so the scene is always there" , 
> cancel/restart the session performance penalty is ok? (I'm forced
> to background = true)

There is indeed a performance penalty. I suppose I should make a
screencast tomorrow when at the desk so you can compare what the
performance difference is. It wasn't that bad, but now that I managed
to get background=false working properly I have to say that it does
feel really nice.

What is the reason you can't render using background=false? No access
to a good ogl context? This used to be the case for me too, but once I
managed to get the ogl drawing to work (session->draw()) it made also
scene updating much more simple.

> 2-
> https://github.com/mcneel/RhinoCycles/blob/5a04498c14779533395bbb59b64
9e33dec4e0f0d/RenderEngines/ViewportRenderEngine.cs#L200-L202
>
> 
I kinda don't understand how do we wait here? assuming you call
> everything from a separate thread, the main thread will handle
> messages and the separate thread will be locked in rendering?

The Renderer() function gets started in a separate thread indeed.
Based on the status of the ChangeQueue (custom implementation in
ChangeDatabase.cs) will, in this old case of background=true
rendering, cancel the session, which will allow the session rendering
thread to join back into the rendering loop of Renderer().

As said, it works, and it isn't all that too bad, but esp. for larger
scenes there will be a noticable pause for the cancel, data upload and
restart.

/Nathan

> 
> cheers, Mohamed Sakr
> 
> On Thu, Nov 12, 2015 at 2:31 PM, Nathan Letwory <nathan at mcneel.com 
> <mailto:nathan at mcneel.com>> wrote:
> 
> And hi again,
> 
> I wanted to illustrate what I'm doing with some links into the
> source of RhinoCycles. It might help see how it could be done. (And
> I'm assuming here I understood Cycles session management properly
> ;)
> 
> Links interspersed in message below.
> 
> On 12/11/2015 14:19, Nathan Letwory wrote:
>> Hi,
> 
>> On 12/11/2015 13:55, Mohamed Sakr wrote:
>>> Hi,
> 
>>> this crashes at some point, any ideas about the general logic 
>>> here? note that I'm working with background = true
> 
>> With my work on RhinoCycles integration I have found that
>> modifying a running render session with background=true isn't
>> very easy to do. You'll have to first cancel the running session,
>> push your changes, then reset and restart.
> 
> Not so long ago I was still using background-rendering in
> RhinoCycles. The update and render cycle look like this:
> 
> https://github.com/mcneel/RhinoCycles/blob/5a04498c14779533395bbb59b64
9e33dec4e0f0d/RenderEngines/ViewportRenderEngine.cs#L150
>
>  This worked together with a check for changes (and possible
> upload) here:
> 
> https://github.com/mcneel/RhinoCycles/blob/5a04498c14779533395bbb59b64
9e33dec4e0f0d/RenderEngine.cs#L150
>
>  - From CheckFlushQueue() you can see that I cancel the session
> before starting upload to Cycles.
> 
>> If you render with background=false you can first pause the 
>> session, then lock, update, reset and unpause.
> 
> Simple start for the render session in RhinoCycles happens here:
> 
> 
> 
> https://github.com/mcneel/RhinoCycles/blob/master/RenderEngines/Viewpo
rtRenderEngine.cs#L153
>
> 
> 
> 
> Up until this basic session, scene and their parameters have been 
> created and connected.
> 
> 
> 
> CheckFlushQueue() checks if there are any changes in the
> changequeue, which at this point will be true. Synchronize() will
> pause the session, push the data, reset and unpause.
> 
> 
> 
> Similarly, while the interactive render session is running I 
> periodically check for new changes, which I do in the class
> governing that: 
> https://github.com/mcneel/RhinoCycles/blob/master/Viewport/RenderedVie
wport.cs
>
> 
, more specifically in the UiUpdate() function here
> https://github.com/mcneel/RhinoCycles/blob/master/Viewport/RenderedVie
wport.cs#L125
>
> 
> 
> Hopefully this helped.
> 
> /Nathan
> 
> 
> 
> 
>>> cheers, Mohamed Sakr
> 
> 
> 
> 
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> 
> 
> 
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- -- 
Nathan Letwory
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