rec.autos.simulators

by **BTM May** » Fri, 20 Mar 1998 04:00:00

I always play N2 using the***pit view. After the 3dfx patch my framerate
increased, but only by a small amount. Just screwing around today, I pressed
f-10 to get the exterior view and was amazed at the performance ---- smooth as
silk. Before 3dfx this was just the opposite, but for some reason with the
3dfx patch my framerate is WAY smoother using the exterior view as compared to
the***pit view. Has anyone else noticed this and does anyone have an idea
why this is the case? You would think the***pit view would be smoother, but
this is definently not the case for me.

by **magefir** » Fri, 20 Mar 1998 04:00:00

> I always play N2 using the***pit view. After the 3dfx patch my framerate
> increased, but only by a small amount. Just screwing around today, I pressed
> f-10 to get the exterior view and was amazed at the performance ---- smooth as
> silk. Before 3dfx this was just the opposite, but for some reason with the
> 3dfx patch my framerate is WAY smoother using the exterior view as compared to
> the***pit view. Has anyone else noticed this and does anyone have an idea
> why this is the case? You would think the***pit view would be smoother, but
> this is definently not the case for me.

this is a fairly well known (among programming circles) issue to
do with car sims and the like on 3dfx chips. having to copy the
whole***pit image into the picture for every single frame creates
a very large performance hit, which is why you notice such an
improvement from outside views. for instance, in Cart Precision Racing
the difference in frame rate with the***pit on and off was something
like 16fps to 24fps on my old P166 with Pure3D. F1RS has a very
small***pit, and so causes minimal frame rate loss.
I can think of a couple of ways of rendering the screen to reduce
this problem, and would hope that they improve this aspect for the
final patch.
I'm actually rather happy with the patch as it is - for some reason
i get a much better feeling of the car now, the frame rate has
improved a bit for me, and it looks better too!

Grant.

by **Pat Dotso** » Fri, 20 Mar 1998 04:00:00

> ERM...This may sound silly, but...Why do they re-draw the***pit in
> every frame? Surely if you drew the***pit once, and then only updated
> the parts of the picture that change (like the view out of the
> windscreen) every frame then you'd get a much better frame rate with a
> larger***pit.

I don't know all the technical ins-and-outs of this, but the
topic has been covered ad nauseum in one of the video card
news groups. For some reason (possibly because the 3dfx
is "3d only"?), it is impossible or at least difficult to
draw the***pit once, and then only updated the parts
of the picture that change on the 3dfx. Maybe the
Voodoo 2 does better? I haven't seen any reports on
Voodoo 2 performance with N2.

Eric Busch can probably cover this one thoroughly.

--
Pat Dotson
IMPACT Motorsports

by **JulianDat** » Fri, 20 Mar 1998 04:00:00

> > ERM...This may sound silly, but...Why do they re-draw the***pit in
> > every frame? Surely if you drew the***pit once, and then only updated
> > the parts of the picture that change (like the view out of the
> > windscreen) every frame then you'd get a much better frame rate with a
> > larger***pit.

Because it can't do a "2D" overlay very well..

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by **ttam** » Fri, 20 Mar 1998 04:00:00

>>ERM...This may sound silly, but...Why do they re-draw the***pit in
>>every frame? Surely if you drew the***pit once, and then only updated
>>the parts of the picture that change (like the view out of the
>>windscreen) every frame then you'd get a much better frame rate with a
>>larger***pit.
>I don't know all the technical ins-and-outs of this, but the
>topic has been covered ad nauseum in one of the video card
>news groups. For some reason (possibly because the 3dfx
>is "3d only"?), it is impossible or at least difficult to
>draw the***pit once, and then only updated the parts
>of the picture that change on the 3dfx.

It isn't, at least if you use Glide API for the game. In Direct3D this
probably isn't possible at the moment, but lately it seems driving
sims and racing sims mainly have 3D***pits anyway (check out for
example CPR, SODA and TOCA), making this disadvantage disappear for
Voodoo cards, as other cards don't have an advantage drawing 3D
***pits.

***

http://www.racesimcentral.net/

by Jo » Fri, 20 Mar 1998 04:00:00

>I always play N2 using the***pit view. After the 3dfx patch my framerate
>increased, but only by a small amount. Just screwing around today, I pressed
>f-10 to get the exterior view and was amazed at the performance ---- smooth as
>silk. Before 3dfx this was just the opposite, but for some reason with the
>3dfx patch my framerate is WAY smoother using the exterior view as compared to
>the***pit view. Has anyone else noticed this and does anyone have an idea
>why this is the case? You would think the***pit view would be smoother, but
>this is definently not the case for me.

I've noticed the sam thing on my P200/M3D.

Joe

by Jo » Fri, 20 Mar 1998 04:00:00

>Because it can't do a "2D" overlay very well..

Does the Voodoo2 handle 2d overlays better? Or is the solution to go
to true 3d***pits?

Joe

by **Jim Sokolof** » Fri, 20 Mar 1998 04:00:00

> Not true for Glide games, which Nascar 2 3Dfx is too. Glide API has
> this "don't write over these pixels ever" feature, which makes sure
> that the non-moving parts of a***pit don't have to be redrawn
> every image. Are there any other moving parts in the***pit besides
> the two gauges (speed and rpm I think) made of single red,
> non-textured polygons, and a few small lights anyway? Those are the
> only parts of the***pit which should be redrawn every frame.

The "pit radio" displays (F1-F9) are also drawn in the***pit
area.

3dfx would have needed the source code for certain! And I imagine that
the restrictions were based on time-to-market rather than any sense of
"Don't do this one thing that would really make it kick-ass"... :-)

There is already some level of support in the software rendering
engine that prevents excessive blitting of pixels that haven't
changed, but it's non-trivial in a multiple-buffering environment to
remember which buffer has which pixels in it. Perhaps it just wasn't
worth the time to sort out all the bugs and just blit the whole thing
each time? Regardless, it's WAG'ing for us...

---Jim

by **Shum Chun Pong Bernar** » Sat, 21 Mar 1998 04:00:00

: why this is the case? You would think the***pit view would be smoother, but
: this is definently not the case for me.

3dfx special behavior. That's why most new driving games lacks the
***pit. NFSSE2,International Rally Championship...

Bernard Shum

by **ttam** » Sat, 21 Mar 1998 04:00:00

>>Because it can't do a "2D" overlay very well..

>Does the Voodoo2 handle 2d overlays better?

In a way that it has more texture memory (make the 2D overlays by
using textured polygons) and overall higher performance, I would say
yes.

***

http://www.netlife.fi/users/ttammi/

by **magefir** » Wed, 25 Mar 1998 04:00:00

Off topic regarding the original message content, but still on
topic regarding the topic itself...

as an extra bit of info for those who don't realise it,
turning on Anti-aliasing with Voodoo1 cards DOES cause a slowdown.
i've got it turned off for my 3dfx-nascar2. And I actually prefer the
display with AA turned off:) When i first ran it with AA on, my
thought was "eek, this isn't very smooth". which is actually what
everyone else has been saying in this newsgroup. Turn off the AA
and you'll be up to 30fps with all detail.

The slowdown is caused by the Voodoo chipset not supporting AA in
hardware, it has to be emulated via playing with the alpha settings
and drawing some extra very small triangles along the edges of your
polygons, which is transparent to the programmer since there is a
function in the Glide dll that does this automatically. but it still
causes a slight performance hit.

I am not sure about Voodoo2 - does this do AA in one pass? Would
anyone like to buy me a Voodoo2 card so i can try? :)

Grant.

by **Brian Bus** » Wed, 25 Mar 1998 04:00:00

I'd love to, but I'd also love to buy me one!

Brian

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