UFFI problem / doubt

Hi alvaro

Thanks for the question. If you have any suggestion for the booklet on
UFFI let us know.
I will let esteban anwser because I do not know.
BTW did you check the chipmunk existing bindings?

Stef

On Fri, Sep 15, 2017 at 3:42 PM, alvaro piorno
<[hidden email]> wrote:
> Hi everybody, i´m using UnifiedFFI with Chipmunk2D library .
> I want to get a pointer to a C Structure (cpBody) and set a position to it.
> I have a subClass of FFIOpaqueObject to handle pointer.
>
> This is the "new " ffiCall :
>     self ffiCall: #(cpBody* cpBodyNew(cpFloat m, cpFloat i))
>
> And this is a "seter" ffiCall:
>
>     self ffiCall: #( void cpBodySetPosition( self, cpVect vector ) ).
>
> I`m not getting any "error" but the position is not updating.
> I tried the same using Chipmunk directly and it works, so there is a problem
> with what i have in Pharo.
> Any suggestion?
> Thanks in advance.
>
> Alvaro Piorno

On Fri, Sep 15, 2017 at 9:42 PM, alvaro piorno <[hidden email]> wrote:

Hi everybody, i´m using UnifiedFFI with Chipmunk2D library .

I want to get a pointer to a C Structure (cpBody) and set a position to it.

I have a subClass of FFIOpaqueObject to handle pointer.

This is the "new " ffiCall :

    self ffiCall: #(cpBody* cpBodyNew(cpFloat m, cpFloat i))

And this is a "seter" ffiCall:

    self ffiCall: #( void cpBodySetPosition( self, cpVect vector ) ).

I`m not getting any "error" but the position is not updating.

I tried the same using Chipmunk directly and it works, so there is a problem with what i have in Pharo.

A general approach might be to write your own C wrapper around Chipmunk library functions which 

just does a debug printout of parameters before calling the wrapped function.

Use these for both from Pharo and your "direct" trial, and see how they compare.

cheers -ben

On Mon, Sep 18, 2017 at 12:01 AM, alvaro piorno
<[hidden email]> wrote:
> Pierce: I already see the repo, i kwnow now the difference and is not the
> problem i have now. I made the suggestion for book draft i found, because
> theres is no example on it. Thanks for answer.
>
> Stephan : Yes, as Esteban said i´m using that, I´m extending (or trying)
> Esteban´s project. And i´m having the problem that esteban metioned. Thanks
> for answer.
>
> Ben: I have in C the same example as in Pharo using the physics of Chipmunk,
> and in C is working fine, there is a problem in the call to the function
> from Pharo in 64 bits. Thanks for answer.

Replicating the same example in C was not my point.
You'd said you'd already done that ;)

I meant compile your own shared C library containing...
    cpBody* myBodyNew(cpFloat m, cpFloat i))
    {
        printf( "....\n", m, i );
        cpBodyNew(cpFloat m, cpFloat i);
    }

and from Smalltalk use...
    self ffiCall: #(cpBody* myBodyNew(cpFloat m, cpFloat i))

also changing your existing C example to also use  myBodyNew()
to confirm it works as expected.

cheers -ben

>
>
> 2017-09-17 12:11 GMT-03:00 Ben Coman <[hidden email]>:
>>
>>
>> On Fri, Sep 15, 2017 at 9:42 PM, alvaro piorno <[hidden email]>
>> wrote:
>>>
>>> Hi everybody, i´m using UnifiedFFI with Chipmunk2D library .
>>> I want to get a pointer to a C Structure (cpBody) and set a position to
>>> it.
>>> I have a subClass of FFIOpaqueObject to handle pointer.
>>>
>>> This is the "new " ffiCall :
>>>     self ffiCall: #(cpBody* cpBodyNew(cpFloat m, cpFloat i))
>>>
>>> And this is a "seter" ffiCall:
>>>
>>>     self ffiCall: #( void cpBodySetPosition( self, cpVect vector ) ).
>>>
>>> I`m not getting any "error" but the position is not updating.
>>> I tried the same using Chipmunk directly and it works, so there is a
>>> problem with what i have in Pharo.
>>
>>
>> A general approach might be to write your own C wrapper around Chipmunk
>> library functions which
>> just does a debug printout of parameters before calling the wrapped
>> function.
>> Use these for both from Pharo and your "direct" trial, and see how they
>> compare.
>>
>> cheers -ben
>>
>