Re: [Chicken-users] SWIG and c-callback with arguments

[Bastian Müller]

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Am 20.08.2007 um 12:22 schrieb Bastian Müller:

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> Am 20.08.2007 um 01:38 schrieb felix winkelmann:
> > On 8/20/07, Bastian Müller <address@hidden> wrote:
> > > >
> > > The code doesn't crash. The callback get's called. That's not the
> > > problem.
> >
> > Oh, well. Then everything is fine.
> >
> > > What's missing, is the support for argument passing.
> >
> > C_save should work ok. What exactly does happen?
>
> In ode.i:
> static void
> EGG_near_callback (void *closure_root, dGeomID o1, dGeomID o2) {
>   C_save(o1);
>   C_save(o2);
>   C_callback(CHICKEN_gc_root_ref(closure_root), 2);
> }
>
> scheme callback:
> (define (near-collision geom1 geom2)
>   (write "near collison") (newline)
>   (let ((body1 (ode-geom-get-body geom1))
>         (body2 (ode-geom-get-body geom2))
>         ...
>
> >>>
> "near collison"
> Error: Type error in argument #1: expected struct dxGeom *|dGeomID:  
> "bad argument type"
>
> I think EGG_near_callback gets called in the ODE internals with real
> dGeomIDs and near-callback get's real dGeomIDs. The problem is,
> that all swig-interface functions don't handle the real data but
> swig-pointers to the actual data. That means, ode-geom-get-body
> expects an swig-pointer to an "struct dxGeom *|dGeomID" and not
> the actual dGeomID. I think the error-message is in this case somehow
> misleading.
>
> Is that correct? If so, any idea how to fix that?
Finally I got this to work. As I thought, the problem was, that the  
interfaced
functions expected swig pointers. So I made swig pointers, the  
functions got
swig pointers and everyone was happy ;-)

%{
static void
EGG_near_callback (void *closure_root, dGeomID o1, dGeomID o2) {
  C_word *known_space = C_alloc(C_SIZEOF_SWIG_POINTER);
  C_word o1p = SWIG_NewPointerObj(o1, SWIGTYPE_p_dxGeom, 0);
  C_save(o1p);

  known_space = C_alloc(C_SIZEOF_SWIG_POINTER);
  C_word o2p = SWIG_NewPointerObj(o2, SWIGTYPE_p_dxGeom, 0);
  C_save(o2p);

  C_callback(CHICKEN_gc_root_ref(closure_root), 2);
}
%}

Thanks!

- --
Bastian Müller - http://turbolent.com/


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