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View Full Version : drastic fps drop on highest detail mip w GF3.



fritzlang
01-22-2002, 06:37 PM
help!
im getting a huge framerate drop when getting close to textured walls. I use 2 tx units on a geforce3, a small simple scene and a mb of textures, 1 bind per unit/frame. i've tried all ways of drawing. it occurs when i approach a wall stright forward and get into the most detailed base mip level range. it is fine on all other mipmap levels
(=camera not moving straight towards a wall)
tried both .bmp and .tga and 16/24/32 bit z-buffers. 1280x1024x32 drops from 85->50 &
1024x768x32 from 120-> 60
?
thank you for your help.

Thaellin
01-23-2002, 04:57 AM
Small question: have you already tried disabling texturing to see if you get a similar performance drop with no textures involved?

Just making sure the problem is isolated...
-- Jeff

Xmas
01-23-2002, 05:04 AM
Because of the numbers, I guess you have vsync enabled.
So it might well be that the "real" framerate is usually above 120 fps, but when you approach a wall it drops just below 120 fps, which in combination with vsync gives you 60 fps.

davepermen
01-23-2002, 05:11 AM
*crosspost*

fritzlang
01-23-2002, 09:16 AM
it is v-sync for sure!
(still surprised that two tx units are much more heavy than one,
i was under the impression (nvidia GF3 faq's) that a second unit
is almost free)

thank you for you help.

AlexH
01-24-2002, 02:49 AM
(still surprised that two tx units are much more heavy than one,
i was under the impression (nvidia GF3 faq's) that a second unit
is almost free)


It doesn't need to be very much. If framerate drops at 119.5 Hz instead of 120, vsync will already sync you on 60 Hz. The small difference can come from the additional transfer overhead due to the second unit's texcoords.
- Alex

Humus
01-24-2002, 03:29 AM
Shouldn't the drivers give you tripplebuffering if Vsync is on?