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Thread: drastic fps drop on highest detail mip w GF3.

  1. #1
    Member Contributor
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    drastic fps drop on highest detail mip w GF3.

    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.

  2. #2
    Member Contributor
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    Re: drastic fps drop on highest detail mip w GF3.

    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

  3. #3
    Senior Member Frequent Contributor
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    Re: drastic fps drop on highest detail mip w GF3.

    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.
    Georg Kolling, Imagination Technologies
    Please ask questions specific to PowerVR hardware or SDKs on the PowerVR Insider Forum
    DevTech@imgtec.com | http://www.powervrinsider.com

  4. #4
    Senior Member OpenGL Pro
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    Re: drastic fps drop on highest detail mip w GF3.

    *crosspost*
    http://davepermen.net - if i could stay true to my heart, i would feel totally free

  5. #5
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    Re: drastic fps drop on highest detail mip w GF3.

    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.

  6. #6
    Junior Member Newbie
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    Re: drastic fps drop on highest detail mip w GF3.

    (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

  7. #7
    Senior Member OpenGL Guru Humus's Avatar
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    Re: drastic fps drop on highest detail mip w GF3.

    Shouldn't the drivers give you tripplebuffering if Vsync is on?

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