[ODE] Record and Playback

[Jon Watte]

For Direct3D, it does. There are other parts of DirectX. And there's OpenGL. And there's GDI. We got tired of finding all the cases, and just put in a detect-and-repair at the beginning of each simulation step. You don't want to write unconditionally, because it's a rather long stall to write this register; just write if it's not what you want. Reading the register is cheap; comparing and branching is not cheap but cheaper than writing the register.

Cheers,

			/ h+


-----Original Message-----
From: DjArcas [mailto:djarcas at hotmail.com]
Sent: Wednesday, January 28, 2004 9:01 AM
To: Jon Watte; Marty Rabens; 'Martin C. Martin'
Cc: ode at q12.org
Subject: Re: [ODE] Record and Playback



> > FP precision/rounding modes - are these controlled via processor
> > instructions?  How/what do I do in this regard to ensure maximum
> > reproducibility?  Any info would be appreciated.
>
> Yup. It's the floating point control word bits, set with fldcw (get the
x86 Instruction Set Reference PDF from Intel -- it's about a 1000 page
download).
>
> Warning: calling some DLLs (including DirectX) will change the rounding
and precision bits from underneath you. Re-set the bits at the start of each
simulation step!

Doesn't creating your D3d device with D3DCREATE_FPU_PRESERVE do that for
you?