Understanding the internals of Bullet-C API

[josemarin]

Hi!

I'm using Bullet-C API, and have a question about the type of the objects.

They type is defined as

#define PL_DECLARE_HANDLE(name) typedef struct name##__ { int unused; } *name

So, a handle to a rigid body type would be declared like this:

PL_DECLARE_HANDLE(plRigidBodyHandle);

And it's used like this:

void plSetPosition(plRigidBodyHandle object, const plVector3 position)
{
btRigidBody* body = reinterpret_cast< btRigidBody* >(object);

...
}

Why not simply use void* to hold the objects, and use static casts?


Thank you.

Jose

[Erwin Coumans]

Why not simply use void* to hold the objects, and use static casts?

void* doesn't have type checking, handles do: for instance the compiler will prevent exchanging a rigidbody handle with a shape handle.

Hope this helps,
Erwin

[josemarin]

And this is a good thing when you are hunting down a mysterious bug!

Thank you, Erwin.