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frame rate drops on final approach

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frame rate drops on final approach

Postby travellingmatt » Tue Jan 13, 2015 8:46 pm

Hi guys,

Wondered if anyone has come across this one?

I have just upgraded to V3.2 from 2.6, so I have the new scenery. Obviously that's heavier in my machine, so frame rate has dropped from 45-50 to 334ish with roughly the same level of details.
That's not the problem. the problem seems to be that when I've been flying around for a while, as i drop below around 2000 feet the frame rate starts to drop maybe 1 FPS per 100 feet. this means by the time I get to ground level I have maybe 4 FPS.

A quick take off and fly round at below a couple of thousand feet does not do this. It only occurs once I have been up at a reasonable height for a real flight.

Take off is usually around 25-35 FPS. The CPU is running around 30% so it's not that. Memory is around 1.9Gb, which is below 50%,
The weird thing is that if I stop and reload scenery once the frame rate starts to drop, it springs back to around 30 FPS. initially I thought it was something to do with 'simplification ' of the scenery, as this solved the problem, (Though I tended to find myself landing in mid air or below the ground) but just a reload is enough.

CPU is AMD A8-5600K quad core 3.6GHz. Graphics is Nvidia GTX650TI 2Gb DDR5 VRAM. I'm running hardware anti-aliasing on top of flightgear.

OS is win7 64bit, and it occurs to some degree with any plane I have tried.

Note this occurs with both Rembrandt or ALS.

Any suggestions? Is this a bug?

Matt
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Re: frame rate drops on final approach

Postby ludomotico » Tue Jan 13, 2015 9:33 pm

travellingmatt wrote in Tue Jan 13, 2015 8:46 pm:The weird thing is that if I stop and reload scenery once the frame rate starts to drop, it springs back to around 30 FPS.


I think this was a known bug with small triangles in the scenery: thousands of random objects are generated on them and the FPS drop a lot. As you report, reloading the scenery fixes the FPS to normal values.

If I'm right, this bug is already fixed in the nightly builds and will be fixed in FG 3.4. In 3.2, try switching random objects off.

I have the same videocard as you and I have consistently much more FPS. Hardware AA does use some frames, though, and I'm not using it.
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Re: frame rate drops on final approach

Postby Thorsten » Wed Jan 14, 2015 6:14 am

Yep - reads like the random objects bug.
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Re: frame rate drops on final approach

Postby travellingmatt » Wed Jan 14, 2015 6:40 pm

Thanks for that, guys. I'll try that later. I do have random objects and random trees turned on. Does this apply to random trees as well?


EDIT: tried that and problem solved. 33 FPS all the way to the ground even with everything turned all the way up on the shaders. (random trees on plus forest at max)


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