NewtonWorldGetFirstBody bug with NewtonBodyGetUserData

[arkdemon]

Hello everyone. I have a problem with NewtonBodySetUserData and NewtonBodyGetUserData: even if I set NewtonBodySetUserData correctly, when I get the user data with NewtonBodyGetUserData (with NewtonWorldGetFirstBody), it returns wrong values which makes my program crash. However, it works when I have the NewtonBody pointer but not when I do this:

Code: Select all

for(NewtonBody *b = NewtonWorldGetFirstBody(world); b != NULL;
       b = NewtonWorldGetNextBody (world,  b)){
       info = (Info*)NewtonBodyGetUserData(b);//wrong values

So here is the code:

Code: Select all

    static inline void DynamicBox(glm::vec3 pos, float mass, glm::vec3 d, Info &info,
                                  NewtonBody *b){
        dgMatrix m = dgMatrix(dgQuaternion(), dgVector(pos.x,pos.y,pos.z,1.f));
        NewtonCollision *c = NewtonCreateBox(world, d.x, d.y, d.z, 0, NULL);
        NewtonBody *b = NewtonCreateDynamicBody(world, c, &m[0][0]);
        NewtonBodySetUserData(b, (void*)(&info));
        NewtonBodySetMassProperties(b, mass, c);
        NewtonDestroyCollision(c);

        NewtonBodySetForceAndTorqueCallback(b, ApplyForceAndTorque);
        NewtonBodySetTransformCallback(b, ApplyTransform);

        Info *i = (Info*)NewtonBodyGetUserData(b);//It gets the correct value
        printf("%u %u %.3f %i\n", i->m, i->t, i->life, NewtonBodyGetID(b));//It returns the correct value
        return b;//not necessary but sometimes I need it to set a velocity
    }

Thank you for your help

[Julio Jerez]

That can not be possible, getFirstBody getNextBody simple iterate over the list of bodies, you must have a bug.

check to see if the pointe to the body that you get form getFirstBody I sthe body that you expect.

[Julio Jerez]

my guess Is that the problem is here: static inline void DynamicBox(glm::vec3 pos, float mass, glm::vec3 d, Info &info, NewtonBody *b){

make sure that Info &info is not a local object created in the stack because it gets destroyed when the function returns.
That will make it work in the second code fragment but fail when you try to read after the function return.

[arkdemon]

Hello, thank you a lot! Yes, it was because the user data was destroyed after the function ended. Thank you!