[osg-users] OSG in non-continuous rendering

Faraz Ravi faraz at igloo-soft.com
Thu Oct 18 16:46:54 PDT 2007

Hi All


I'm taking a look at OSG and I really like what it offers. I am looking to
possibly use it in a CAD like environment where it is windowed and there is
no continuous rendering loop. Rendering is performed as and when it is
required, for example if the viewpoint is changed. This is important since
the scene may take 0.5s or more to render and is degraded for higher fps
during movement. 


I've adapted the fltk example to test this and it seems to work fine. So
what I wanted to know is:


1.       Does OSG have any internal dependencies on a continuous rendering

2.       Are there any known uses of OSG like this, or in a similar

3.       Is there anything else I need to be aware of if I am doing this? 


Note that when there is a continuous rendering loop in the fltk example the
UI performance is hit badly, ie menus slow down and so on - it would also
hit any CPU processes so this is not really a realistic model for my


I noticed osgDirector uses a continuous loop with wxWidgets, seems to work
quite well. I guess its rendering in another thread.


On a different note does anyone know what method OSG uses to manage
coordinate truncation / scaling issues when dealing with the teapot in the
desert like scenario? Does it performance multiple passes or is there a
different coordinate frame for each scale? Lets say I wanted to show a
building in a large landscape without losing coordinate precision in the
building for example.



Thanks for any help











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