[ODE] Stepfast bug fix

[Adam D. Moss]

Hi!
Is this patch reversed?  It looks like it probably is.  Thanks
for sending a patch, but next time please send it as an attachment,
since line-wrapping and tab-spacing have killed the patch's
applicability when pasted into the body. :/

I would apply it by hand, but I'm not 100% sure about the
(un)necessary zeroing of the 4th componant; I think we like to
ensure sane real numbers in the 'padding' of vectors and matrices
so that we can't accidentally keep doing maths on NaNs in the
generic ODE matrix/vector ops and cripple our speed on archs
which issue exceptions every time (PPC/OSX).  That's probably not
an issue for various reasons, but I don't feel confident enough
to apply that aspect of the patch without more opinions.

I'll apply the accel-saving part by hand now.
Thanks,
--Adam

Joe Ante wrote:
> Probably a bit late now that quickstep is here...
> Can someone check this into cvs.
> 
> Step fast didn¹t save the acceleration/torque when gravity was disabled.
> I also removed the unneccessary assigments of zero values. And only setting
> the body tag one time instead of 3 times inside the loop.
> 
> 
> --- /Users/joachima/Desktop/Ode/oldode-040513/ode/src/stepfast.cpp      Sun
> May 16 16:33:25 2004
> +++ /Users/joachima/Desktop/unity/External/ode/ode/src/stepfast.cpp     Wed
> May  5 22:26:49 2004
> @@ -777,13 +777,13 @@
>         dReal *globalInvI = (dReal *) ALLOCA (nb * 12 * sizeof (dReal));
>         for (b = 0; b < nb; b++)
>         {
> -               for (i = 0; i < 3; i++)
> +               for (i = 0; i < 4; i++)
>                 {
>                         saveFacc[b * 4 + i] = bodies[b]->facc[i];
>                         saveTacc[b * 4 + i] = bodies[b]->tacc[i];
> -               }
>                 bodies[b]->tag = b;
>         }
> +       }
>  
>         for (iter = 0; iter < maxiterations; iter++)
>         {
> @@ -820,13 +820,9 @@
>                                 body->facc[0] = saveFacc[b * 4 + 0] +
> body->mass.mass * world->gravity[0];
>                                 body->facc[1] = saveFacc[b * 4 + 1] +
> body->mass.mass * world->gravity[1];
>                                 body->facc[2] = saveFacc[b * 4 + 2] +
> body->mass.mass * world->gravity[2];
> +                               body->facc[3] = 0;
>                         }
> -                       else
> -                       {
> -                               body->facc[0] = saveFacc[b * 4 + 0];
> -                               body->facc[1] = saveFacc[b * 4 + 1];
> -                               body->facc[2] = saveFacc[b * 4 + 2];
> -                       }
> +
>                 }
>  
>  #ifdef RANDOM_JOINT_ORDER
> @@ -899,7 +895,7 @@
>                 {
>                         body = bodies[b];
>  
> -                       for (i = 0; i < 3; i++)
> +                       for (i = 0; i < 4; i++)
>                         {
>                                 body->facc[i] *= ministep;
>                                 body->tacc[i] *= ministep;
> @@ -917,7 +913,7 @@
>                 }
>         }
>         for (b = 0; b < nb; b++)
> -               for (j = 0; j < 3; j++)
> +               for (j = 0; j < 4; j++)
>                         bodies[b]->facc[j] = bodies[b]->tacc[j] = 0;
>  }
> 
> 
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> 


-- 
Adam D. Moss   . ,,^^   adam at gimp.org   http://www.foxbox.org/   co:3