well i installed NFS4: Road Challenge (european version of "High Stakes"), and the only mode i can select in the 3D cards is "Direct3D".

While it seem to work, framerate is a lot better, though i found that sometimes, when there is more "polygons" and textures shown on screen, there are some kind of hiccups, meaning it "hangs" for a fraction of second" before resuming the game again, it's almost negligible, but maybe this is caused by the "Direct3D" option?

If this problem is caused by Direct3D, then how can i force the game into Glide mode?

Again, i'm using Amigamerlin's Voodoo3/4/5 drivers v2.9 for Win98.

NFS4 simply doesn't support Glide I think...

in the reference card, it say "3D Graphics accelerator using 3dfx Voodoo Graphics, Voodoo 2, Voodoo Banshee, or other Direct 3D compatible card." And it talk about "Glide drivers" inside as well.

RaptorZX3 wrote on 01.09.13 at 17:50:46:

in the reference card, it say "3D Graphics accelerator using 3dfx Voodoo Graphics, Voodoo 2, Voodoo Banshee, or other Direct 3D compatible card." And it talk about "Glide drivers" inside as well.

Honestly, I don't remember if NFS4 has glide support or not.
BTW the statement you reported doesn't suggest that 3dfx video cards are supported in glide mode. Many games simply reported a compatibility with 3dfx accelerators in D3D/OpenGL or states they were particularly optimized for 3dfx adaptors, but true glide support is another story;)

In this case, if the readme speaks about glide drivers somewhere, well, this is one of those ambiguity that need to inquire further.

I remember a post from ps47 that may be useful: http://www.falconfly.de/cgi-bin/yabb2/YaBB.pl?num=1077242013/6#6

I had the same problem, but with NFS5 and Voodoo2.

I solved it back them editing the 3dsetup.ini file.

I changed

CARD_3Dfx Voodoo2 /M:dx /I
with
CARD_3Dfx Voodoo2 /M:voodoo2 /I

Maybe you can do something like that in NFS4 for Voodoo5, I'm not sure, but take a look.

This article might help you also:
http://www.zeckensack.de/glide/nfsfix/