Re: [GD-Consoles] PS2 floating point

[Research \(GameBrains\) <res...@ga...>]

We are still looking at the problem, but it seems that calculations =
resulting in small numbers are the problem.  On GameCube and PC the =
results are correct but on the PS2 it's not.  Still a good possibility =
that there is simply a bug in our code somewhere too :-)  The cool thing =
about multi-platform development is a lot of times different hardware =
and different compilers help you find bugs you would have never found =
otherwsie....
Cheers,
Brett

----- Original Message -----=20
From: "J. Grant" <jg-...@jg...>
To: <gam...@li...>
Sent: Thursday, February 27, 2003 10:33 PM
Subject: Re: [GD-Consoles] PS2 floating point


> Hi Brett,
>=20
> Out of interest what was the problem with your implementation?  I =
found
> that -fshort-double stopped some of the problems I was having with one
> issue when I tested some float stuff a while ago.  However, if the =
code
> is the problem then this would not solve that.
>=20
> JG
>=20
> Research (GameBrains) wrote:
> > Gareth,
> > Found it! (moved to chapter 8 in 6th edition).  Thank you very much!
> > Brett
> >=20
> > ----- Original Message -----=20
> > From: "Gareth White" <gw...@ra...>
> > To: <res...@ga...>
> > Cc: <gam...@li...>
> > Sent: Thursday, February 27, 2003 2:49 PM
> > Subject: Re: [GD-Consoles] PS2 floating point
> >=20
> >=20
> >> There are indeed subtle differences between the PS2 and the IEEE =
implementation.
> >>=20
> >> Try the 'EE Core User's Manual' (2nd Edition), Page 77, Chapter 4
> >> 'Floating-Point Unit (FPU)', section 4.8 'IEEE 754 Compatability'
> >>=20
> >> Cheers.
> >>=20
> >> ---
> >> Gareth White - Engine Programmer - Ratbag Pty Ltd
> >> Level 8, 63 Pirie Street, Adelaide, SA, Australia, 5000
> >> Ph: +61 8 8223 5830, Fax: +61 8 8223 5746, Mob: 0403 942668
> >> http://www.ratbaggames.com/
> >>=20
> >> ----- Original Message -----
> >> From: "Research (GameBrains)" <res...@ga...>
> >> To: <Gam...@li...>
> >> Sent: Thursday, February 27, 2003 4:46 PM
> >> Subject: [GD-Consoles] PS2 floating point
> >>=20
> >>=20
> >> Hello,
> >> Our physics engine is experiencing some odd behavior on the PS2.  =
We traced it
> >> to our resting contact force calculation where sometimes it seems =
the result is
> >> not quite right, but it works fine on other platforms.  I don't =
know if it's an
> >> urban legend or what, but I have heard that the PS2 has some quirks =
with regard
> >> to floating point numbers and so I thought I would just ask and see =
if this is
> >> something I need to look at or not.  If so, what are the =
differences between the
> >> PS2 IEEE implementation and is there a doc describing them?
> >> Thanks,
> >> Brett
>=20
>=20
>=20
>=20
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