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.

2017-09-17 12:11 GMT-03:00 Ben Coman <btc@openinworld.com>:

On Fri, Sep 15, 2017 at 9:42 PM, alvaro piorno <alvaropiorno100@gmail.com> 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