[Robotics] Triggering a Blender frame calculation from an external programme...

[Benoit Bolsee]

The socket suggestion can work well I think. 

It consists in having a Python controller that runs on every frame and
blocks on a socket until it gets a data. Since the game engine is single
threaded, that will block the whole simulation. Once the controller
returns, the game engine will compute one full frame. 

In addition you have to enable the 'compute all frame' option so that
the simulator ignores the actual time interval between frames and
computes the next frame as if exactly 1/frame_rate seconds elapsed since
last frame, so you'll get physically correct simulation.

Note that this method can work with any kind of blocking signal, not
just socket.

Hope this helps,
Benoit

> -----Original Message-----
> From: robotics-bounces at blender.org 
> [mailto:robotics-bounces at blender.org] On Behalf Of Herman Bruyninckx
> Sent: lundi 10 janvier 2011 18:03
> To: Blender and Robotics
> Subject: Re: [Robotics] Triggering a Blender frame 
> calculation from an external programme...
> 
> 
> On Mon, 10 Jan 2011, Markus Mehrwald wrote:
> 
> > if you use sockets you can create a blocking one and stay 
> there until 
> > you send something from your 'master'.
> 
> Does the game engine also block...?
> 
> > Hope this helps or is the problem more complex then I am 
> thinking at 
> > the moment?
> 
> I don't know exactly what you are thinking :-) But I am 
> interested in finding out whether or not one can let Blender 
> wait to do a frame computation until a certain external event 
> has occured. The use case for this would be when we want to 
> use the Blender simulator in a time-synchronized way with 
> other "components", and they all have to progress together, 
> time step by time step.
> 
> > Markus
> 
> Herman
> >
> >
> > Am 10.01.2011 16:50, schrieb Herman Bruyninckx:
> >> Dear all,
> >>
> >> does anyone happen to know how to make Blender work as a 'slave', 
> >> waiting to do its next frame simulation only when 
> triggered (in one 
> >> way or another) by an external programme?
> >>
> >> Thanks!
> >>
> >> Herman
> >> _______________________________________________
> >> Robotics mailing list
> >> Robotics at blender.org 
> >> http://lists.blender.org/mailman/listinfo/robotics
> >>
> >
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> > http://lists.blender.org/mailman/listinfo/robotics
> >
> 
> -- 
> --
>    K.U.Leuven, Mechanical Eng., Mechatronics & Robotics Research Group
>      <http://people.mech.kuleuven.be/~bruyninc> Tel: +32 16 328056
>    EURON Coordinator (European Robotics Research Network) 
<http://www.euron.org>
   Open Realtime Control Services <http://www.orocos.org>
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