Jim Wilson wwrites: > >"Curtis L. Olson" <[EMAIL PROTECTED]> said: > >> So, I will assert that distance is a better metric than time. Time >> may work ok, if you are flying in a straight line it is probably >> equivalent, but when you consider that at any time a pilot could turn >> and fly any direction, distance based caching makes the most sense. > >Yes I can see that. But how do we manage cache for the fdm? >Perhaps each fdm should just have its own cache, covering a smaller fixed >radius.
Yes each needs it own scenery cache No need to give them a smaller radius however we will want to come up with some scheme so that duplicated tiles are 'shared' >This could mean some tile loading when we switch views, If we use separate caches this shouldn't have any effect >Hmmm...actually, now that I think of it, the real problem is >that suddenly >switching view positions will create a mess when there are >tile loads pending >and the current view now wants to discarded them. Of course >it won't actually >try to unload a pending tile, but there could be some nasty >thrashing for a bit. yes this will effect the tile loader queue in that it is a FIFO but if the planes are in close proximity to one another ie within a tile or two this shouldn't be too bad in that most of the tiles will be shared. >I'm going to add something that checks the viewer based query against a >tolerance of change so that we'll save time if the aircraft moves only a short >distance. Probably something like, if lon=oldlon && lat=old-lat return >oldelev. Then a tolerance check (if we're only looking at a very tiny change) >also return oldelev. I could do that in the viewer update and only query the >tilemgr if position actually changes. This will preclude modeling bumps and potholes realistically :-( FWIW the terrain intersection code is 'quite quick' compared to what it used to be. < it ranked < 500 last time I did a profile check > >From my perspective figuring out the best way to share tiles and changing the Viewer code to use the ssgContext Class structure so we can have views within a view < insert windows > are the priority items. Norman _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
