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How to fix lag in flightgear

Graphics issues like: bad framerates, weird colors, OpenGL errors etc. Bad graphics ar usually the result of bad graphics cards or drivers.
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Re: How to fix lag in flightgear

Postby Johan G » Sun Jun 06, 2021 6:23 am

A large contributor to CPU and GPU workload is the sheer amount of data that need to be shuffled around to render the scenery. You can alter how much and how detailed scenery to render by changing the level of detail (LoD) ranges (Main Menu > View > Adjust LoD Ranges).

Some computers have an integrated graphics chipset that they primarily use even though they have a dedicated graphics card, though this is usually only relevant for laptop computers.
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Re: How to fix lag in flightgear

Postby Richard » Sun Jun 06, 2021 5:24 pm

wkitty42 wrote in Sat Sep 28, 2019 12:25 pm:FWIW: you don't need NVTT... .they will be cached uncompressed... so mainly NVTT will help save drive space only


Using DDS with DXT compression (i.e. NVTT) you also get the same space saving on your GPU because pretty much all GPU's can work directly with compressed DDS - so NVTT is definitely worth having, in my opinion.

V12 wrote in Sat Sep 28, 2019 9:17 pm:Strange, problem is only with some .png textures. When I one problematic texture converted into .jpg, it was displayed correctly.


There are some textures that just don't work as DDS; so I've added logic to exclude these and that logic keeps getting improved as more of the edge cases are discovered.
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If we can't reliably use NVTT across all platforms then we have a few options to do something different - but it's a lot more work and might take a while before the cross platform issue is resolved.
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Re: How to fix lag in flightgear

Postby V12 » Mon Jun 07, 2021 5:14 am

TackledMirror14 wrote in Sat Jun 05, 2021 11:04 pm:I have an AMD Ryzen 5 6-Core CPU, MSI Radeon RX 570 Series graphics card, and 16 gigs of RAM, but it runs like its on a PC from 1996. Any idea why?

What operating system ? Windows, Linux or Mac ?
Check if You have working graphics drivers, with Linux, Radeons are bit problematic, but after fiddling with configuration usable. RX570 is perfectly enough for FG.
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Re: How to fix lag in flightgear

Postby vnts » Mon Jun 07, 2021 1:59 pm

Richard wrote in Sun Jun 06, 2021 5:24 pm:If we can't reliably use NVTT across all platforms then we have a few options to do something different - but it's a lot more work and might take a while before the cross platform issue is resolved.

Those comments were from 2019 - those DDS edge cases have probably been fixed since then(?). In the recently updated hardware recommendations page (link) I recommended people turn the DDS cache on .

One thing I'm not clear on: is NVTT currently bundled with the Windows installer? A search of the /bin folder doesn't show any results for files with nvtt in their name.

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Re: How to fix lag in flightgear

Postby wkitty42 » Mon Jun 07, 2021 4:31 pm

NVTT should come with NVIDIA drivers... idk if it is available standalone...
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Re: How to fix lag in flightgear

Postby Richard » Tue Jun 08, 2021 12:41 pm

vnts wrote in Mon Jun 07, 2021 1:59 pm:is NVTT currently bundled with the Windows installer


It's osgdb_nvtt.dll that you need and I don't believe that this is currently included in the distribution partly because the underlying NVTT library can be difficult to build.

Equally I'm not sure how many people (apart from me) have actually successfully built and used osgdb_nvtt.dll on any platform.
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