[osg-users] osg::Image::update?

Hartmut Seichter lists at technotecture.com
Sat Jul 26 19:17:32 PDT 2008


Robert Osfield wrote:
> Hi Hartmut,
>
> On Sat, Jul 26, 2008 at 2:02 AM, Hartmut Seichter
> <lists at technotecture.com> wrote:
>   
>> Well, osgART has a number of PlugIns implementing their own
>> osgART::VideoImageStream which implements update slightly
>> different. But I am happy to quickly change things over as we are targeting
>> the latest OSG
>>     
>
> For 2.6 all original ImageStream implementation - the ones in the
> Quicktime and Xine plugins are all exactly the same as before, and
> function in exactly the same way.  osgArt::VideoImageStream should be
> no different - all existing mechanisms will work.
>
> The new Image::update(..) method is only called if you attach an
> update callback to the texture, this is something that is now done
> automatically for osg::ImageSequence images being assigned to
> textures, but not for any other Image types.  You could add this is
> you so wished.
>
>   
That was exactly what we did with osgART ... we attached a 
osgART::ImageUpdateCallback in order to trigger the update. I think I 
will dive more into ImageStream and ImageSequence to see if we can get 
rid of our (osgART) additional implementation.

>> Are there any plans to differentiate between open() and play() ... this was
>> the main reason for us  to have osgART::VideoImageStream as we need to know
>> in osgART which dimensions and colorspace the imagestream supports
>>     
>
> I haven't made any other plans for ImageStream.  ImageSequence is just
> a subclass of it at present.  The osgDB::ImagePager is a companion to
> it, which could expand in its role - for instance it could potentially
> drive the various ImageStream classes, so rather than have their own
> threads, they'd use the ImagePager's ImageThreads to drive them.  This
> would help when handling many video streams at one time, and also
> improve the handling of thread cancellation on exit.
>
>   

Yes, that is one area where we have some additional logic in VideoStream 
to deal with threading issues like locking, or double buffering. As I 
said before I need to take a deeper look ImageSequence and the 
ImagePager which might solve a lot of problems for us already.


Cheers,
Hartmut

> Robert.
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>   


-- 
Hartmut Seichter, PhD (HKU), Dipl-Ing.(BUW), Postdoctoral Fellow, HITLabNZ




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