On Sunday, December 16, 2012 21:37:37 James Turner wrote: > On 16 Dec 2012, at 19:18, Stuart Buchanan wrote: > > I'm surprised there's any benefit to using a very low resolution texture > > set. Surely the normal textures are already loaded by OSG and it's > > cheaper just to refer > > to those rather than loading some more textures? Or are we not > > sharing our textures > > between tiles? > > Right, I had exactly the same thought. > > Of course, if by some terrible mistake we aren't sharing textures, that > would be a very big bug, but hopefully easy to fix! > > James >
I'm replying to multiple messages here: James: I have no clue how and if the textures are shared, or if the osg cache is related to this. All I know is that I can see a difference. I could explain it in my simplistic view: the current position holds the large textures for all material within the inner zones. If there are materials within the outter zone which are not within the inner zone, their effect is using a smaller texture, at least until they pass into the inner zone. So I could explain it like this: I have Road, DeciduousForest, DrypastureCover in the high res zone, and BroadleafForest,NeedleForest, Rock, Marsh Bog etc in the outter zone. No need to have high res Bog for a triangle 100 km away (keep in mind I also use large res textures, some of which were kindly commited by ThorstenR in the regional set). Regarding the osg cache, I am not familiar with the way it works, and how it shares textures, so forgive me if I can't answer this. Mathias, Stuart, yes I'm only loading the bare surface from the BTG, and not performing any tree, building, model calculations from them (they would be invisible at 20-30 km away, but the osg::LOD just hides it from view, does not prevent from loading in RAM all the objects). Besides reduced scenegraph, the loading speeds for an outer tile are faster. The tilecache model is also changed, so it does not look like a long tail behind the flightpath, but mostly as a rectangle around the plane. I reckon the tower view losing terrain should be dealt by disabling tower view when outside a reasonable distance from the tower. The memory gains are those I spoke about before, and allow me to fly a long time in custom SRTM terrain without running out of RAM. I'd estimate a 1.5 - 2 times improvement in memory cost vs. view distance, at a slight cost of increased disk IO (which is not noticeable, at least running in multithreading mode). I am aware there are better systems out there, I'm just doing what I can within the restrictions of the BTG format. I'd be more than happy to have a real terrain LOD, but right now that means lots of changes in Terragear and simgear. I'll publish the modifications tomorrow, If I can get around to clean the code a bit. Cheers, Adrian ------------------------------------------------------------------------------ LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
