[Haskell-cafe] OpenGL's VBO with Haskell

[Twinside]

Hi Haskell list,

Today I'm turning to you for the use of VBO (Vertex Buffer Object) in
Haskell. I seem
to be able to create one without any problem using the following code :

------------------------------------------------------
vboOfList :: Int -> [Float] -> IO BufferObject
vboOfList size elems =
    let ptrsize = toEnum $ size * 4
        arrayType = ElementArrayBuffer
    in do
    [array] <- genObjectNames 1
    bindBuffer arrayType $= Just array
    arr <- newListArray (0, size - 1) elems
    withStorableArray arr (\ptr -> bufferData arrayType $= (ptrsize, ptr,
StaticDraw))
    bindBuffer ArrayBuffer $= Nothing
    reportErrors
    return array
------------------------------------------------------

However the problem arise when I try to draw primitives using this vbo :

------------------------------------------------------
displayVbo buff size = do
    let stride = toEnum sizeOfVertexInfo
        vxDesc = VertexArrayDescriptor 3 Float stride $ offset 0
        colors = VertexArrayDescriptor 4 Float stride $ offset 12
        texCoo = VertexArrayDescriptor 2 Float stride $ offset (12 + 16)
        filt   = VertexArrayDescriptor 4 Float stride $ offset (12 + 16 + 8)
    bindBuffer ArrayBuffer $= Just buff

    arrayPointer VertexArray $= vxDesc
    arrayPointer ColorArray $= colors
    arrayPointer TextureCoordArray $= texCoo
    arrayPointer SecondaryColorArray $= filt

    drawArrays Quads 0 size
    bindBuffer ArrayBuffer $= Nothing
------------------------------------------------------

Nothing is displayed on screen.

As you can see, my VBO contain interleaved data :
- 3 float for the vertex
- 4 for the color
- 2 for the texture coordinate
- 4 for the secondary color)

The 'offset' function has type Int -> Ptr Float, and is used to forge a
pointer from an Int, to mimic
the C way of using VBO. As far as I've checked, the values in my list for
VBO generation are valid and well
displayed using other techniques.

So is there a workaround other method for my solution, preferably by keeping
my data interleaved?
Secondly,  is there any sample for advanced features like VBOs in Haskell?

Regards,
Vincent