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mip Level Count/mip Map Flag and frame rates

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I've been tweaking with the render ini to try and improve my frame rates whilst flying around the Manchester and Birmingham airport scenery of Steve Brown ( Paul Brooks's scenery also used ). The scenery is excellent but I get the 4 fps problem at times and wonder what the mip level count and mip map flag values mean in the overall scheme of things.I did try a Fly II forum search to get some info on this but had no luck.Also has there been a posting explaining exactly what the frame rate debug info means?Dell inspiron 8200 1.6gHz nVidia GeForce 440 Go 64meg video card;384 meg RAM; Win XPPerhaps Johnny might add the answers to his FAQ page?Thanks in anticipation.:-wave

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Guest tonyc

Try mine. Just remember that I have a g3 128 meg and an xp2000, and my frame rates go through the roof, except when I hit more than a 1024 texture and, as the render.ini shows, only one slot is allocated.tony

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Tony or anybody,I found the 'how to' folder in the FlyII folder and in it is a document about tweaking the render ini file. It states that no matter what video card one has, adjusting either the non AGP or AGP max textures setting from 256_565 = 32 has no effect.Can someone explain the meaning of this and the texture slot allocation and debug info screen to me in easy to understand terms.I have tried to understand some of this info by reading some tutorials on a game developers website but it is too advanced for me.:-(

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Flyfisher,The 4 FPS problem should have more to do with your texture slots than with mipmapping.Briefly, mipmapping is a way to avoid texture aliasing problems. If a texture is applied to some object, and that object moves further away from the observer, the texture must be filtered. Because filtering on most graphics hardware happens by sampling a few discrete points (or even worst, just bi or trilinear filtering), you can run into nyquist problems, which manifest themselves as aliasing. Mipmapping aims to avoid that by supplying pre-filtered versions of textures, typically at half the original res, half _that_ res, etc. It's a lot more complicated than that, but that's the basic idea. Mipmaps take extra texture memory on the graphics card, but not as much as you might at first think.Texture slots are Fly's way of holding textures of various resolutions. For a long time, OpenGL (and maybe also DirectX) had the limitation that texture sizes must be powers of two. Many applications allocate texture memory dynamically, so you don't have to worry about how many textures of what size there might be. Fly, for whatever reason, allocates them statically. This can pose a problem: if you run out of texture slots for some particular size, the texture won't fit on the graphics card, and will have to be shoveled across the AGP bus every single frame. I don't think that itself should cause 4.00 FPS type slowness (AGP-4X is pretty dang fast), but if it gets too bad, it seems to. Sometimes it also just slows framerates, but not to that degree (e.g, maybe you get 12 where you should get 20+).The trick is to make sure that you have your texture slots set to the maximum number of textures of a given size that might ever be loaded at once. Naturally that's a bit hard to determine, but you can use the numbers in the debug screen to help you somewhat.Static texture allocation of the type Fly uses has a few advantages, but IMHO the user should never have to deal with such things, as they do in Fly. One obvious drawback of static allocation is that it can waste huge amounts of graphics card memory. You pretty much have to allocate as many slots as you might ever use, but if your average use is far smaller, then you have wasted all the difference. I believe that happens a lot in Fly, and the efficiency of graphics memory utilization is typically quite low.If Fly was an open source project, I'd have a go at rewriting that subsystem from scratch, but, well, it isn't, and so I can't :)Anyway, I hope that was a useful explanation of mipmaps and texture slots.John/madmax

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You might also want to check out the "Tweak Kit For FlyII" by Gerhard Schenerecker and "The MemCalc Version 1.1" by Jeff Burke in the Fly!II Development file library.The Librarian.

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