[ODE] Stepfast - auto-disable stuff

[Frederic Ferland]

Any chance this could be added to CVS so that it is not lost and that we 
don't have to make these changes every time there's a new release of ODE? 
(especially since we already have the docs for this...)

Thanks!



At 02:15 PM 7/14/2003 +0300, you wrote:
> > the documentation defines a number of other functions that are not
> > actually implemented in the source:
> >   dBodySetAutoDisableThresholdSF1
> >   dBodyGetAutoDisableThresholdSF1
> >   ...
>
>These weren't implemented in the stepfast source. I've implemented these for
>my LTGameJam - that required some small modifications to ODE core.
>
>You can either try to grab the source from http://jammy.sourceforge.net/2003
>("dingus.zip", dingus/lib/ode, look for "Araz" comment :)), or I can explain
>it in basic steps here:
>
>Changes to ODE internal files (hm, my naming convention differs from ODE's
>:)):
>objects.h:
>     add to struct dxBody:
>         int mDisableSteps; // auto-disable counter
>     add to struct dxWorld:
>         dReal mAutoDisableThreshold;
>         int mAutoDisableSteps;
>ode.cpp:
>     add to dBodyCreate(dxWorld* w):
>         b->mDisableSteps = 0;
>     add to dWorldCreate():
>         w->mAutoDisableSteps = 10;
>         w->mAutoDisableThreshold = REAL(0.008);
>     add functions like (add their prototypes to public objects.h):
>         void dWorldSetAutoDisableSteps( dWorldID w, int steps )
>        {
>            dAASSERT(w);
>            w->mAutoDisableSteps = steps;
>        }
>        void dWorldSetAutoDisableThreshold( dWorldID w, dReal threshold )
>        {
>            dAASSERT(w);
>            w->mAutoDisableThreshold = threshold;
>        }
>stepfast.cpp (actually one needs to add this to "normal" ODE's solver also):
>     insert approx at line 1016, at start of loop for( bb=world->firstbody;
>... ):
>         // ---- code begin ------------------------
>         if( !(bb->flags&dxBodyDisabled) ) {
>             bool disable = true;
>             const dReal *lvel = bb->lvel;;
>             dReal lspeed = dDOT(lvel,lvel);
>             if( lspeed > world->mAutoDisableThreshold ) {
>                disable = false;
>             } else {
>                 const dReal *avel = bb->avel;
>                 dReal aspeed = dDOT(avel,avel);
>                 if( aspeed > world->mAutoDisableThreshold ) {
>                     disable = false;
>                 }
>             }
>             if( disable )
>                 ++bb->mDisableSteps;
>             else
>                 bb->mDisableSteps = 0;
>             if( bb->mDisableSteps > world->mAutoDisableSteps ) {
>                 bb->flags |= dxBodyDisabled;
>             }
>         }
>
>         // ---- code end ------------------------
>     add approx. at line 1080 (with above code included), in "traverse and
>tag all body's joints, add untagged..." code:
>        n->body->flags &= ~dxBodyDisabled; // this line exists
>        n->body->mDisableSteps = 0; // add this line
>        n->body->tag = 1; // this exists
>
>Basically, that's all :)
>
>
>Aras Pranckevicius aka NeARAZ
>http://www.gim.ktu.lt/nesnausk/nearaz/
>
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______________________________________________________________

Frederic Ferland <fref@bigfoot.com>
Computer Game Programmer
Strategy First (www.strategyfirst.com)