NULL argument

I'm little rusty with VB, but here I go. I'm trying to pass a NULL to a function that requires a ByRef variable. In C++, you just pass NULL, but how do you do that in VB?

Can you not use the optional keyword and pass it nothing??

I can't. I'm calling a Win API function.

Which function is it and whats the data type? Have you tried vbnull?

It's DirectX graphic function:

D3DXSkinnedMesh.UpdateSkinnedMesh(BoneTransformsIn As Any, BoneInvTransforms As D3DMATRIX, retMesh As D3DXMesh)

where BoneInvTransforms is a ByRef parameter. I need to pass a null, but how?

It appears that the D3DMATRIX is a C struct so you might try 0&

I've tried that.

It returned:

Compile error: ByRef argument type mismatch.

Allapi seem to Nothing on this page here (http://www.allapi.net/vbtutor/directx1.shtml), whilst working with DirectX. Different function but worth a go if you haven't already tried.

Everywhere I look for this method, it comes up like this...
Sub UpdateSkinnedMesh(BoneTransformsIn As Any, retMesh As D3DXMesh)
(I copied this out of the object browser when I had set a
reference to the DirectX 8 VB library, msdn had the same thing.)
It only shows 2 parameters but you have three?
Anyway, 0& should be a Null pointer passed ByRef. ByVal 0&
would be an actual Null value. I don't know what is going on, but
Squirm probably will.

Both MSDN (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dx8_c/hh/dx8_c/graphics_iface_d3dx_8yuw.asp) for C++ and VB and the object browser are telling me its got 2 parameters:

object.UpdateSkinnedMesh( _
BoneTransformsIn As Any, _
RetMesh As D3DXMesh)

object
Object expression that resolves to a D3DXSkinMesh object
BoneTransformsIn
First element of an array of D3DMATRIX types, representing the bone transforms.
The length of this array is the count of all the bones in the skin mesh
RetMesh
A D3DXMesh object, to be filled with the generated skinned mesh.


Its the same for both 8 and 8.1. Wonder where you got your definition from.

:-\