Hi,

sorry for the delay, was dragged into the admin zone ;(

On Mon, 2009-06-22 at 17:56 -0500, Carsten Neumann wrote:
>       Hello Marc,
> 
> Marc Hofmann wrote:
> >  > hmm, is there anything particular holding you back to use OpenSG 2,
> >  > more in a technical sense than the time/effort it will surely take
> >  > with deadlines to cope ?
> >  >
> >  > And yes I'm quite serious, the area you are having problems in is really
> >  > one of the worst parts of OpenSG 1 and a lot of effort went into
> >  > correcting these things for OpenSG 2. So in this situation it might be
> >  > really worth considering to switch if there aren't any big technical
> >  > hurdles.
> >  >
> >  > If there are let us know and we can address them.
> >  >
> > 
> > we didn't thought about changing to OpenSG 2 yet, because our 
> > application is really big and it would take "too much" time to convert 
> > everything.
> > 
> > I have some questions about OpenSG 2.
> > 
> > What is the state of OpenSG 2.0 and when will it be officially released?
> 
> the one area where I expect changes before a release are the way shaders 
> are composed/overridden, which may have some how state/state changes are 
> handled.

hmm, that should not matter to apps coming from 1.x as long as the
compat stuff works.

> > What features from 1.8 are missing in 2.0? We need especially cluster 
> > support and multithreading.
> 
> I think of the big things only the VolRen support is missing in 2.0, 
> cluster and multithreading are definitely ported and working. With all 
> the attention the ref counting got it should actually be better.

The biggest change is the disappearance of the algorithm viewports, in
particular FBOViewport and ShadowViewport. And the split of the texture
chunk into textureobj and textureenv.

> > What are your experiences converting a large application so far?
>
> I've not ported any large applications, only small ones. Perhaps others 
> have experience they can share?

I did it a couple of times for a reasonable big one and so far did not
have to many problems. But that highly depends on how you integrate
with OpenSG. For the one in question basically the app structure did
not derive from OpenSG but just referenced/mapped to it. So it was
relatively straight forward and I kept both versions living in parallel.

Except for the mentioned parts above, they usually require some level of
redesign in the application, and that is something I still have to find
some time to finish completely as it is more a spare time project right
now and as I did not write the system it takes longer that it would
normally take if I would have written it ;) . Similar your own OpenSG
containers will require some reworking.


The best way is to start from building OpenSG 1.x with
--enable-osg2-prep and prepare your app for the change in interfaces,
in particular getField (const + non const) to getField (const) and
editField (non const) and the switch to BoxVolume for Nodes as well
as a simplification of Matrix/Vector interfaces

Than switch to OpenSG 2, build with all compat options enabled. The
most likely things you encounter are the following:

- FieldMasks of Fields that exists no longer (Geometry / Shader)
- ParentPtrs are FCPtrs not NodePtrs (Core)
- Working reference counting !
- Changes from RenderAction to DrawEnv in parameters
- Boost instead of our own rather nasty functors.

I'll try to compile a list of most common changes and how to map them
and put them into the wiki.

> > How long would it approximately take? Would you advise to use it in a 
> > "production" system?
> 
> The group here at UL Lafayette uses it for our demos and applications we 
> develop and I think Gerrit does the same in Singapore. All development 
> effort goes into 2 these days and personally I find it increasingly 
> difficult to debug the details of 1.x, just because I'm not that 
> familiar with it anymore.

I can only agree with Carsten, I actually would prefer 2.x to 1.x for
production systems as it went through much more rigid testing with
external tools like valgrind. Some we missed, but once found the fixes
are usually much faster and of better quality because the surroundings
are much sounder than for 1.x.

kind regards,
  gerrit






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