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sjdibble

GeForce 4 'go slow' using GL_FILL mode

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I have a strange GeForce 4MX problem and wondered if anyone has any idea what is going on. I am experimenting with creating and optimising a (currently flat and featureless) grid of triangles which will eventually be a 3D terrain. I have implemented Quadtree indexing and frustum culling. The program has a toggle for fill mode, which switches between glPolygonMode(GL_FRONT,GL_FILL) or glPolygonMode(GL_FRONT,GL_LINE) When drawing 120 vertices (20 triangles) on my computer, a 1Ghz AMD with a GeForce 3 Ti 200, I get about 1380 FPS in FILL mode and 1420 FPS in LINE mode. However, on my brothers PC, a 1.7Ghz Athlon with GeForce 4 MX 440, we get 33 FPS (yes, really, not a mistype, it is thirty three) in FILL mode to a massive 1600+ FPS in LINE mode. I dont think it''s the framerate counter as the camera movement is frame rate dependant so there is a noticable slowdown in camera movement speed. The number of vertices rendered is generated each frame by the rendering method, not by me counting polygons on screen and there is no texturing or lighting going on either. This has to be something I have done, because other app''s dont do the same on the GeForce4 using OpenGL. Any idea ? Stephen.

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a gf3 is actually a better card than a gf4mx BUT thats not the problem.
both though have good fillrate,
do both use the same drivers?
try commenting out code until u find which line causes the big slowdown

http://uk.geocities.com/sloppyturds/gotterdammerung.html

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The GeForce 4 is using the latest NVidia drivers and the GeForce 3 (a Creative Labs card) uses the latest Creative drivers. We did consider this as the first problem.

The line which appears to be causing the slowdown is the

glVertex3f(...

but only when in GL_FILL mode.

I have re-written the renderer to work using glDrawElements however we get similar results. (Well, the GeForce 3 speeds up quite a bit)

The fact that the FPS changes by over 1000 FPS merely because I specify GL_FILL rather than GL_LINE suggests it''s something to do with the fillrate, however, it cant be just the hardware, there has to be a software problem as well, just only one that effects GeForce4 cards and not GeForce 3.

I think I will stick my old GeForce 2 back in and see what results I get. If this still doesn''t work, I''ll make use of my free web space and stick it on my homepage to see if other people get similar problems or whether it''s just my brother.

Stephen

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Well, weird

The GeForce 2 at 120 vertices give

FILL - 600
LINE - 980

Any more ideas anyone ?

If not, I''ll post the code where others can try it out !

Stephen

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I have now made the program available at

http://mysite.freeserve.com/sjd_programming/tbv6c.zip

I would be grateful if a few people (particularly those with GeForce 4 MX cards) could run it and let me know what sort of performance you get, including the number of vertices and the FPS for FILL and LINE mode (F to swap between the two).

Thanks in advance

Stephen

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i dunno if your verteces are correct. It seems to say 90 to 72 when i am looking straight down at a one

It ran at 100fps lines and 90fps fill.
*kick starts the voodoo"

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The terrain is implemented using a quadtree. Its the culling of unseen branches that has the bug in it. This vertices in branches which cannot be seen are nevertheless, sometimes, being sent to the renderer.

Stephen

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i get +2000fps on both fill and line, no change when i change fillmode.

My System Information:
----------------------

Operating System: Windows XP Professional Version: 5.1.2600
Processor Type: AMD Athlon XP 1800+ 1533MHz
Physical Memory: 392692KB
Hard Drive: C:\ Total Space: 19532MB Free Space: 7549MB Cluster Size: 4 KB
CD-ROM Drive: Pioneer 16x DVD, LG 8x4x32 CDR
Monitor: Generic Monitor
Display Info: 1280 x 1024 16777216 colors, 32-bit, 72hz
Pointing Device: Saitek GMI USB Mouse
Network: NONE
Modem: Standard 56k Modem
Sound Card: Creative Sound Blaster LIVE! 1024
Video Card: 128 MB nVidia GeForce4 ti 4200

Video specific:
---------------

vSync: Off by default in both DX & GL
Clock Speeds:
Core: 270 mHz
Memory: 540 mHz

PCI Mode Memory: Both DX and GL Profiles Set to use 1 meg of sys memory in PCI mode
--------------------------------------------------------------

Even worse, the performance doesnt seem to die when i use AA
Ive got my drivers using hardware acceleerated lines too, that could be it.

Oh yea, use the nvidia drivers for the creative card, preferably the ones you''re using on your card.

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