Hi Glenn,
Thanks for your quick reply as always:) Changing topic title to use more
appropriate terms. See comments below:
> I used to refer to the technique you're using as "lazy rendering"
> (i.e. only render a frame when something has changed) ... try
> searching the archives ...
When searching the archives for "lazy rendering" through Google Groups
and Gmain, I only found to posting on the subject, of which this one
comments the former:
http://article.gmane.org/gmane.comp.graphics.openscenegraph.user/8859/match=lazy+rendering
> I have run into the same issue. PagedLOD children "expire" after a
> certain period of time (default is something like 5 seconds?) If a
> PagedLOD child has not been visited in the last N seconds, the pager
> will discard it and revert to a lower LOD. OSG updates the
> "time-last-visited" during the cull traversal in order to check for
> expiration. So, if you are not continuously running the frame loop,
> PagedLOD's will think their children have expired and will drop to the
> lowest LOD.
> [snip]... but at the time I never did find a good way to do this in
> OSG without confusing the pager.
Hmmm... that's what I feared. Ok, I am just thinking aloud here since
this is a problem I really need to get solved:
For real-time rendering paging out children on expery time is a good
idea to keep memory consumption at minimum. However, this obvious does
not work for "lazy rendering".
What if the pager could be configured in the following way for "lazy
rendering":
* Set a "maximum" memory size osgDB::DatabasePager can occupy.
* When a new page/sub-graph is added,
osgDB::DatabasePager::removeExpiredSubgraphs() will remove the oldest
pages if the "maximum" limit is exceeded.
Would this be a feasible strategy? Or are there better ways/strategies
to support lazy rendering of pagedLOD databases?
Best regards,
John Larring
Glenn Waldron wrote:
John,
I have run into the same issue. PagedLOD children "expire" after a
certain period of time (default is something like 5 seconds?) If a
PagedLOD child has not been visited in the last N seconds, the pager
will discard it and revert to a lower LOD. OSG updates the
"time-last-visited" during the cull traversal in order to check for
expiration. So, if you are not continuously running the frame loop,
PagedLOD's will think their children have expired and will drop to the
lowest LOD.
I used to refer to the technique you're using as "lazy rendering" (i.e.
only render a frame when something has changed) ... try searching the
archives ... but at the time I never did find a good way to do this in
OSG without confusing the pager.
Glenn
--
Glenn Waldron : Pelican Mapping : http://pelicanmapping.com :
+1.703.652.4791
On Wed, Jul 30, 2008 at 8:39 AM, John Vidar Larring
<[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>> wrote:
Hi all,
Background:
-----------
In our application the user can set up scenes ( or sequences as we
call them) for playback on a timeline (e.g. seq.1 - transition -
seg.2 - transition ... seq.N). Some scenes are too complex to render
real-time and are recorded to movies before playback. Hence, when
scenes are edited by the user all scenes are redrawn as needed
rather than continuously to avoid sluggish GUI response.
Problem:
--------
_Sometimes_ when the scene is redrawn in edit mode (i.e. redraw only
if needed), the pagedLOD DB (osgTerrain) drops to the lowest detail
level (Ref. osg_original.jpg and osg_problem.jpg). This behavior
seems to appear at randomly. In playback mode (i.e. when frame rate
is constant) the problem never occurs.
Reproduce / Code example:
----------
The problem has been reproduces in a small test program
(osgtest_source_code.tgz) derived from the osgviewerQT example
(since we are using Qt 4.x in our application). To reproduce: run
the compiled application: 'osgtest -t <your osgTerrain db>' . To
trigger refreshes, occlude parts of the window with another window.
The problem typically reveals itself when at a redraw or when the
window looses focus (be patient, since this happens randomly it may
take some time before the problem occurs).
Since I'm still quite new to OSG, I'm not sure where to look for a
solution. Hopefully someone will spot the obvious error in the
sample code. Any advice is highly appreciated.
Versions:
---------
OSG svn rev 8700
Qt 4.2.3
Best regards,
John Larring
--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.
_______________________________________________
osg-users mailing list
[email protected]
<mailto:[email protected]>
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
--
This message has been scanned for viruses and
dangerous content by *MailScanner* <http://www.mailscanner.info/>, and is
believed to be clean.
------------------------------------------------------------------------
_______________________________________________
osg-users mailing list
[email protected]
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
--
Best regards,
John
WeatherOne
--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.
_______________________________________________
osg-users mailing list
[email protected]
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
