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
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