[Bf-committers] Improvement of BGE rendering for CAVE systems

Julian Adenauer julian.adenauer at zmms.tu-berlin.de
Tue Nov 29 15:12:28 CET 2011


I have an additional question concerning the synchronization for CAVE
systems:
Has anyone tried to implement a framelock in Blender? Or integrated
support for G-Sync cards
(http://www.nvidia.com/page/quadrofx_gsync.html)?
Ideas how to do that?

Best,
Julian

On Tuesday, November 29, 2011 11:03 AM, "Damien Touraine"
<damien.touraine at limsi.fr> wrote:
> Hi,
> 
> We are working hard on Blender CAVE. Actually, we use a python script to 
> synchronize informations (for the moment, position and orientation of 
> each object) between the rendering nodes (the master node multicasts the 
> information to several slaves).  This script is running as a controller 
> triggered by an "always" sensor activated each frame. This Logic is 
> attached to a camera.
> 
> However, we don't have find an optimal solution : the scheduling of all 
> Logics can make the Blender CAVE script running before the update done 
> by other Logic (for instance, translation of an object triggered by 
> keyboard). The results is a desynchronization between the master and the 
> slaves. In some case (armature mouvement), the update of the slaves may 
> not occur.
> 
> Is there any way to force the execution of a given script AFTER all 
> other Logic ?
> If not, I can suggest a patch : I have seen that there is 
> bge.types.KX_Scene.pre_draw that permits the integration of specific 
> function just before drawing the scene. But this is not optimal, as this 
> method is call before each redraw. Thus, in case of stereo, it is call 
> twice per frame (ie : once per point of view). So, I have devevelopped a 
> patch that add bge.types.KX_Scene.pre_render that is called once per 
> frame and before the rendering of the frame. But I'm not sure this 
> solution is optimale and is in the aim of Blender Game Engine. May I 
> post it to projects.blender.org ? Moreover, we may have to add a 
> bge.types.KX_Scene.pre_swapBuffers to synchronize the " *SwapBuffer" 
> between rendering nodes.
> 
> In addition, I wish to develop blenderCAVE as a plugin. But, as it rely 
> on the game engine, I don't manage to do that. Is there any way to link 
> an addon with BGE ?
> 
> Regards
>      Damien Touraine
> On 04/11/2011 21:36, Dalai Felinto wrote:
> > Hi Damien,
> >
> > It's strange, I could swear I had replied to your post in the forum
> > [1]. I have been in touch with Jorge Gascon for the BlenderCAVE
> > project and he pointed me to your idea.
> >
> > For your patch the better place to put it is in the
> > projects.blender.org website and post here the link. I'll be glad to
> > look at your patch.
> >
> > What I've been thinking (and it may be a better topic for the tracker
> > instead) is if it wouldn't be more interesting to really support
> > caves. For example, to introduce in the interface the options required
> > to setup the number of walls, the wall distance, ... But I never
> > visited a cave so I don't know how standard the output from the
> > visualization tools are.
> >
> > Anyways, an option to set individual projection matrixes per stereo
> > eye seems good too.
> >
> > Cheers,
> > Dalai
> > [1] -http://www.blender.org/forum/viewtopic.php?p=90396
> >
> > 2011/11/4 PabloVazquez.org<venomgfx at gmail.com>:
> >> BTW, I just tried it live yesterday :)
> >>
> >> Here at Universidad Rey Juan Carlos in Móstoles (Madrid), it was awesome,
> >> specially with 3D glasses, still some little things to fix, but the overall
> >> experience is very rich, just needs cool graphics to make it more awesome!
> >> :)
> >>
> >> --
> >> Pablo Vazquez
> >> CG Artist
> >> Blender Foundation Certified Trainer
> >> E-mail:contact at pablovazquez.org
> >> Website:http://www.pablovazquez.org
> >>
> >>
> >> On Fri, Nov 4, 2011 at 17:32, Ton Roosendaal<ton at blender.org>  wrote:
> >>
> >>> Hi,
> >>>
> >>> Interesting stuff! I'll make sure our dome/vr guru Dalai Felinto will
> >>> check on it :)
> >>>
> >>> -Ton-
> >>>
> >>> ------------------------------------------------------------------------
> >>> Ton Roosendaal  Blender Foundationton at blender.org      www.blender.org
> >>> Blender Institute   Entrepotdok 57A  1018AD Amsterdam   The Netherlands
> >>>
> >>> On 4 Nov, 2011, at 14:32, Damien Touraine wrote:
> >>>
> >>>> Hi,
> >>>>
> >>>> I'm working on the BlenderCAVE project
> >>>> (http://www.gmrv.es/~jgascon/BlenderCave/). Its purpose is to use
> >>>> blender to render on CAVE systems
> >>>> (http://en.wikipedia.org/wiki/Cave_Automatic_Virtual_Environment).
> >>>> We use python API to synchronize the scene across all computers that
> >>>> render on a screen. Python API is also used to adapte the camera to
> >>>> the
> >>>> current screen (ie : the one that is attached to the current
> >>>> computer).
> >>>> For this feature, it is important to be able to define precisely the
> >>>> projection matrices for both eyes independently. More specically, we
> >>>> must be able to adapt the projection to the right position of the user
> >>>> eye. For instance, you can to turn on yourself while looking on the
> >>>> floor screen. With default stereocopy viewing mode of BGE the eyes of
> >>>> the user must stay parallel to the screen and "horizontal".
> >>>>
> >>>> Although we have searched, we haven't found any way to define
> >>>> projection
> >>>> matrix for left eye independently from right eye through the python
> >>>> API.
> >>>> Thus, we suggest a patch we have developped. This patch creates two
> >>>> projection matrices  (left and right eye) besides the current one
> >>>> for a
> >>>> given camera. It manages the rendering for daily use (ie.: outside
> >>>> BlenderCAVE project).
> >>>> I can send the patch that is based on SVN version 41510 (uncompressed
> >>>> "svn diff" : ~12K) on this list. But I'm not sure that it is the right
> >>>> place.
> >>>>
> >>>> Regards
> >>>>      Damien Touraine, long time developper of CAVE applications
> 
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