1 files changed, 16 insertions, 3 deletions

diff --git a/src/LambdaCube/GL/Mesh.hs b/src/LambdaCube/GL/Mesh.hs
index 95ca582..384cdd1 100644
--- a/src/LambdaCube/GL/Mesh.hs
+++ b/src/LambdaCube/GL/Mesh.hs
@@ -46,13 +46,18 @@ data GPUMesh
   , gpuData   :: GPUData
   }
 
-addMeshToObjectArray :: GLStorage -> String -> [String] -> GPUMesh -> IO Object
+addMeshToObjectArray :: GLStorage
+                        -> String   -- ^ Slot name for a PrimitiveStream.
+                        -> [String] -- ^ Uniform names.  IORefs will be put in 'objUniSetup'.
+                        -> GPUMesh
+                        -> IO Object
 addMeshToObjectArray input slotName objUniNames (GPUMesh _ (GPUData prim streams indices _)) = do
     -- select proper attributes
     let (ObjectArraySchema slotPrim slotStreams) = fromMaybe (error $ "addMeshToObjectArray - missing object array: " ++ slotName) $ Map.lookup slotName $! objectArrays $! schema input
         filterStream n _ = Map.member n slotStreams
     addObject input slotName prim indices (Map.filterWithKey filterStream streams) objUniNames
 
+withV :: (v a -> (Ptr a -> io) -> io) -> v a -> (Ptr () -> io) -> io
 withV w a f = w a (\p -> f $ castPtr p)
 
 meshAttrToArray :: MeshAttribute -> Array
@@ -77,11 +82,17 @@ meshAttrToStream b i (A_M44F  v) = Stream Attribute_M44F b i 0 (V.length v)
 meshAttrToStream b i (A_Int   v) = Stream Attribute_Int b i 0 (V.length v)
 meshAttrToStream b i (A_Word  v) = Stream Attribute_Word b i 0 (V.length v)
 
-updateMesh :: GPUMesh -> [(String,MeshAttribute)] -> Maybe MeshPrimitive -> IO ()
+-- | Update a mesh without allocating new buffer objects.  Each update must
+-- provide new values for all existing array elements.
+updateMesh :: GPUMesh                     -- ^ Mesh to be updated.
+              -> [(String,MeshAttribute)] -- ^ A list of updates.
+              -> Maybe MeshPrimitive      -- ^ Ignored.
+              -> IO ()
 updateMesh (GPUMesh (Mesh dMA dMP) (GPUData _ dS dI _)) al mp = do
   -- check type match
   let arrayChk (Array t1 s1 _) (Array t2 s2 _) = t1 == t2 && s1 == s2
-      ok = and [Map.member n dMA && arrayChk (meshAttrToArray a1) (meshAttrToArray a2) | (n,a1) <- al, let a2 = fromMaybe (error $ "missing mesh attribute: " ++ n) $ Map.lookup n dMA]
+      ok = and [ Map.member n dMA && arrayChk (meshAttrToArray a1) (meshAttrToArray a2)
+                 | (n,a1) <- al, let a2 = fromMaybe (error $ "missing mesh attribute: " ++ n) $ Map.lookup n dMA]
   if not ok then putStrLn "updateMesh: attribute mismatch!"
     else do
       forM_ al $ \(n,a) -> do
@@ -98,6 +109,8 @@ updateMesh (GPUMesh (Mesh dMA dMP) (GPUData _ dS dI _)) al mp = do
                 (a,b) -> a == b
 -}
 
+-- | This allocates buffer objects.  Use 'disposeMesh' to free them.  Use
+-- 'updateMesh' to modify the allocated buffer object data.
 uploadMeshToGPU :: Mesh -> IO GPUMesh
 uploadMeshToGPU mesh@(Mesh attrs mPrim) = do
     let mkIndexBuf v = do