[Flightgear-users] Are FlightGear object textures cached/shared between models?

[Greg H. <gr...@on...>]

Hi all,

I have been creating some scenery objects around Melbourne, and noticed 
some unexpected behaviour in FlightGear.

One characteristic of Melbourne is that there are several large/tall 
buildings around the CBD that are all very similar.  These buildings 
were erected by the Housing Commission in the 50's and 60's. They all 
appear to have been designed by the same committee: they are extremely 
ugly, have near-zero architecture significance, and all share the same 
external features.  I thought they would be reasonably easy to model for 
use in FlightGear, and -- because the same designs were used repeatedly 
-- the same model could be re-used in many locations.

Development is proceeding, but the texture files are currently fairly 
large -- around 205KBytes and 184KBytes for day and night textures, 
respectively. I am working to optimise these files. [Whilst on that 
subject, what is a good/recommended maximum size for the texture files?]

In the meantime, I have noticed that there is a significant pause 
whenever FlightGear renders one of these buildings using these texture 
files.  What's more, there is the /same/ pause when it renders another 
of these buildings in the same session.

This seems to indicate that the texture files are /not/ shared between 
objects; that is, each instance of an object retrieves its own copy of 
the texture files, even if other objects have already loaded the same 
texture.  Can someone confirm that this is the case?  If so, could I 
please suggest that texture files should be shared among all objects 
that use them, so that once a texture is loaded it does not need to be 
reloaded?

It is very distracting to be flying towards a group of Housing 
Commission buildings, and have the simulation pause as one building 
after another comes within rendering range.

Regards,
Greg Hawkes