Hello, >Where this can lead to problems is with textures that have transparency >(i.e. an alpha channel.) The box filter scheme of generating >successively >smaller versions of the texture doesn't work well with the >alpha layer. The >transition from fully opaque to fully transparent gets >wider and wider >relative to the overall texture and can lead to problems.
>More generally, the default box filter scheme of generating the smaller >>versions of the texture files is very simple and usually not quite >optimal, >and is definitely non-optimal when working with textures that >have a >transparency layer. In addition, the mipmaps are generally >computed in >software when the texture is loaded which takes some time. So this is the explanantion of decreasing fps with textures with transparency? Comparing with other games/sims I'm surprised that it is so much noticeable in FGFS. >I suspect that some of these fancier formats might have the mipmap layers >>pre-computed using a more sophisticated size reducing scheme -- thus >>producing slightly better visual results in the end. Slightly? Have you seen the pictures comparing .png vs .dds? This is more than slightly! Indeed .dds creates mipmap layers while converting to it. The qualitity is much better, loading seems to be much smaller compared with .png. Indeed nearly all commercial games and sims uses .dds. The only disadvantage I can see and that's why I never considered yet to use it is the fact that the size itself is increasing. As we have people here which consider space saving more important than qualitity I feared that it could lead to problems. Regards Heiko Regards, Curt. On Mon, Mar 21, 2011 at 9:14 AM, <thorsten.i.r...@jyu.fi> wrote: > Maybe you already did this, but this needs a 'average of 3' (or 5) > tests, because I would be very surprised if the input file format > changes the final frame-rate after loading - it's all uncompressed to > the same format in GPU memory, as far as I know. Yes, I checked it (I couldn't believe it...). Just *maybe* the conversion by gimp screwed the pnd file and altered the texture somehow, so that all derived from the png is then problematic (?). But the effect as far as my procedure is described is real. > The PNG loading time also seems suspicious - decompressing a PNG is > certainly more work than RGB or DDS, but decompressing a 1MB PNG > shouldn't take even one second on a computer of the past few years. Yes - now multiply this by 2500 since it's done for every cloud being loaded, and you get a large number. Of course the system *should* realize that it has the texture loaded already and doesn't need to load it any more, but evidence suggest that it actually decompresses 2500 times. Cheers, * Thorsten ------------------------------------------------------------------------------ Colocation vs. Managed Hosting A question and answer guide to determining the best fit for your organization - today and in the future. http://p.sf.net/sfu/internap-sfd2d _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- Curtis Olson:http://www.atiak.com - http://aem.umn.edu/~uav/ http://www.flightgear.org - http://www.flightgear.org/blogs/category/curt/ -----Integrierter Anhang folgt----- ------------------------------------------------------------------------------ Colocation vs. Managed Hosting A question and answer guide to determining the best fit for your organization - today and in the future. http://p.sf.net/sfu/internap-sfd2d -----Integrierter Anhang folgt----- _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel ------------------------------------------------------------------------------ Colocation vs. Managed Hosting A question and answer guide to determining the best fit for your organization - today and in the future. http://p.sf.net/sfu/internap-sfd2d _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
