Re: [Flightgear-devel] Building of framerate doom

[James T. <zak...@ma...>]

> On 4 Nov 2014, at 07:29, Curtis Olson <cur...@fl...> wrote:
> 
> I think this could touch on something I observed and haven't quite put my finger on either.  When I was running a valgrind session (slow frame rates) it was quite obvious that AI aircraft were removed from the scene graph when they went out of view and were reloaded each time they came back into view.
> 
> This isn't how things are designed and isn't how it has worked in the past, but it appears to be happening as of v3.2.  So I'm sure something inadvertent is happening here.  When I added debugging output to the model loading (effect creating) I could see the effect creation sequence triggered each time the AI model came back into view.
> 
> I was looking at AI models around SFO, but perhaps a similar issue is happening with other models as well.
> 

This is a feature, not a bug :)

All AI models are now PagedLOD nodes, instead of plain LOD nodes, precisely so they can be unloaded.

The rationale (my rationale!) here was that any popping when changing views here, was outweighed by many AI models far outside the view being kept in memory. In general we want to use the OSG paging system for loading and unloading, instead of our own custom logic which was previously happening.

Now, of course the PagedLOD view/distance settings can be adjusted to change when loading / unloading occurs, but I would say the current behaviour is closer to what we want (OSG Pager makes decisions about loading) than the previous situation.

Kind regards,
James