vertex array abstraction forgotten

src/VertexArray.hs

@@ -0,0 +1,97 @@
+{-# LANGUAGE TypeFamilies #-}
+module VertexArray where
+
+import qualified Graphics.Rendering.OpenGL as GL
+
+import SDL (($=), get)
+
+import Foreign
+
+import Control.Concurrent.MVar
+
+-- internal imports
+
+import BufferClass
+import VertexBuffer
+
+data VertexArray = VertexArray
+  { vArrId :: GL.VertexArrayObject
+  }
+  deriving (Eq, Show)
+
+instance Buffer VertexArray where
+
+  type ObjName VertexArray = GL.VertexArrayObject
+
+  target _ = undefined
+
+  glId = vArrId
+
+  initialize va = return ()
+
+  bind va = GL.bindVertexArrayObject $= Just (vArrId va)
+
+  unbind va = GL.bindVertexArrayObject $= Nothing
+
+newVertexArray :: IO VertexArray
+newVertexArray = VertexArray
+  <$> GL.genObjectName
+
+addBuffer
+  :: VertexArray
+  -> VertexBuffer a
+  -> VertexBufferLayout
+  -> IO ()
+addBuffer va vb layout = do
+  -- bind the provided vertex buffer
+  bind va
+  bind vb
+  -- enable and fill out the vertex attrib pointer(s)
+  list <- readMVar (vblElements layout)
+  let indexed = zip [0 ..] list
+      dataElementSize e = case e of
+        GL.Float -> sizeOf (undefined :: GL.GLfloat)
+        x        -> error ("No size computation implemented fof: " <> show x)
+  mapM_
+    (\(index, elem) -> do
+      let offset = fromIntegral $
+            foldl
+              (\acc (index, _) -> acc + index )
+              0
+              (filter ((<= index) . fst) indexed) :: Int
+      GL.vertexAttribArray (GL.AttribLocation index) $= GL.Enabled
+      GL.vertexAttribPointer (GL.AttribLocation index) $=
+        ( vbleHandling elem
+        , GL.VertexArrayDescriptor
+          -- number of components to our attribute
+          (vbleCount elem)
+          -- datatype of elements
+          (vbleType elem)
+          -- ???
+          0
+          -- offset from beginnning of vertex
+          (plusPtr nullPtr (offset * dataElementSize (vbleType elem)))
+        )
+      )
+    indexed
+  unbind va
+  unbind vb
+
+newtype VertexBufferLayout = VertexBufferLayout
+  { vblElements :: MVar [VertexBufferLayoutElement]
+  }
+
+data VertexBufferLayoutElement = VertexBufferLayoutElement
+  { vbleType     :: GL.DataType
+  , vbleCount    :: GL.GLint
+  , vbleHandling :: GL.IntegerHandling
+  }
+
+newVertexBufferLayout :: IO VertexBufferLayout
+newVertexBufferLayout = VertexBufferLayout
+  <$> newMVar []
+
+pushElements :: VertexBufferLayout -> GL.DataType -> GL.GLint -> IO ()
+pushElements vbl type_ count = do
+  modifyMVar_ (vblElements vbl) $ \list ->
+    return (list ++ [VertexBufferLayoutElement type_ count GL.ToNormalizedFloat])