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基於this post,我試圖找出如何在Haskell中使用VBO。我試圖填補未涵蓋有位:OpenGL VBO在Haskell
data Sprite = Sprite { spriteImage :: Image
, spritePosition :: Position
} deriving (Show, Eq)
spriteBatch :: [Sprite] -> [(TextureObject, [Sprite])]
spriteBatch = (map f) . toList . (groupedBy (imageTexture . spriteImage))
where f (t, s) = (t, s)
offset = plusPtr nullPtr
renderSprites :: [Sprite] -> IO()
renderSprites l = (flip mapM_) (spriteBatch l) $ \(t, sps) -> do
textureBinding Texture2D $= Just t
let l = concat $ map sprToList sps
vbo <- vboOfList ((length l)*4) l
displayVbo vbo $ fromIntegral $ length sps
where
sprToList :: Sprite -> [GLfloat]
sprToList (Sprite (Image _ (TexCoord2 u0 v0) (TexCoord2 u1 v1) (Size w h) _) (Position x y)) =
[fromIntegral x, fromIntegral y, u0, v0
,fromIntegral (x+w), fromIntegral y, u1, v0
,fromIntegral (x+w), fromIntegral (y+h), u1, v1
,fromIntegral x, fromIntegral (y+h), u0, v1
]
vboOfList :: Int -> [GLfloat] -> IO BufferObject
vboOfList size elems = do
let ptrsize = toEnum $ size * 4
arrayType = ElementArrayBuffer
(array:_) <- genObjectNames 1
bindBuffer arrayType $= Just array
arr <- newListArray (0, size - 1) elems
withStorableArray arr $ \ptr -> bufferData arrayType $= (ptrsize, ptr, StaticDraw)
bindBuffer ArrayBuffer $= Nothing
return array
displayVbo buff size = do
let stride = 2*(2*4)
vxDesc = VertexArrayDescriptor 2 Float stride $ offset 0
texCoo = VertexArrayDescriptor 2 Float stride $ offset 8
bindBuffer ArrayBuffer $= Just buff
arrayPointer VertexArray $= vxDesc
arrayPointer TextureCoordArray $= texCoo
clientState VertexArray $= Enabled
clientState TextureCoordArray $= Enabled
drawArrays Quads 0 size
bindBuffer ArrayBuffer $= Nothing
你可以找到完整的代碼here,如果你需要。
在master branch上,同樣的功能使用普通的vertex
調用來繪製Sprites
,它的工作原理非常完美。但是使用VBO,這個精靈不在那裏;我得到一個空白屏幕。
任何人都可以向我解釋我在這裏做錯了嗎?
你能向我們解釋第一個地方有什麼問題嗎?它是否編譯和行爲不當? – 2013-04-03 19:34:29
@ ThomasM.DuBuisson:哦,是的,對不起。它編譯完美,但屏幕保持空白。這個精靈並沒有顯示出來 - 它必須在上面的VBO部分,因爲沒有VBO的部分工作得很好。 – Lanbo 2013-04-03 19:38:20