[ODE] why setTransform() ?

[Jani Kajala]

> faster with floating than fixed).  I *think* (but can't give any
> references) the doubles are as fast as floats, but it's been a while


In PC, yes, but in general, no. For example PS2 hardware does not do double
precision floating point arithmetic at all. You can use doubles but those get
emulated in software (resulting maybe 50x penalty in execution time when
compared to float counterparts).


Regards,
Jani Kajala

----- Original Message -----
From: "John D. Gwinner" <jgwinner@dazsi.com>
To: <nathan@whatever.net>; <ode@q12.org>
Sent: Wednesday, January 09, 2002 4:27 AM
Subject: RE: [ODE] why setTransform() ?


> Have to be carefull on the Win32 thing, if you are reading old
> documentation it can be misleading.  I still find references to fixed
> point 32 bit math as an optimization, for example.  (Newer PC's are
> faster with floating than fixed).  I *think* (but can't give any
> references) the doubles are as fast as floats, but it's been a while
> since I hand optimized anything, so I'm not sure now.
>
> Just making the point that the pace of evolution is fast on the PC side,
> it's amazing the number of people say 'well, it's always been that way'
> and of course is completely wrong (now).  I'll have to double check this
> though.
>
>                == John ==
>
>
> > -----Original Message-----
> > From: nathan@whatever.net [mailto:nathan@whatever.net]
> > Sent: Monday, January 07, 2002 6:58 PM
> > To: ode@q12.org
> > Subject: Re: [ODE] why setTransform() ?
> >
> >
> > On Tue, 8 Jan 2002, Russ Smith wrote:
> >
> > > ODE's matrices have 3 rows, not 4. also, ODE matrices may contain
> > > doubles whereas OpenGL matrices contain singles. so some kind of
> > > setTransform() function is needed.
> >
> > Aren't there double version of all of the OpenGL functions?
> > Like glMultMatrixf and glMultMatrixd?
> >
> > I admittedly pretty new to OpenGL, but it seems like there's
> > two entire APIs in there, depending whether you want to use
> > floats or doubles.  Or maybe it's just a Win32 thing.
> >
> > --
> >
> > Nate Waddoups
> > Redmond WA USA
> > http://www.natew.com
> >
> >
> > _______________________________________________
> > ODE mailing list
> > ODE@q12.org
> > http://q12.org/mailman/listinfo/ode
> >
> >
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