Broken binding of central picture in one pass

src/Shader.hs

@@ -1,8 +1,10 @@
 module Shader
-    ( bindArrayBuffers
+    ( bindShaderLayer
     , bindShaderBuffers
+    , bindArrayBuffers
     , drawShader
     , freeShaderPointers
+    , drawShaderLay
     ) where
 --import Geometry.Data
 import Shader.Data
@@ -28,11 +30,41 @@ bindArrayBuffers numVs theVBO = do
         (fromIntegral $ floatSize * numVs * sum (_vboAttribSizes theVBO)) 
         (_vboPointer theVBO)
 
+bindArrayBuffersLayer :: Int -> Int -> VBO -> IO ()
+bindArrayBuffersLayer numVs lay theVBO = do
+    bindBuffer ArrayBuffer $= Just (_vbo theVBO)
+    bufferSubData 
+        ArrayBuffer 
+        WriteToBuffer 
+        (fromIntegral $ floatSize * stride * numSubElements * lay)
+        (fromIntegral $ floatSize * numVs * stride)
+        (_vboPointer theVBO)
+  where
+    stride = sum $ _vboAttribSizes theVBO
+
+bindShaderLayer :: [(Int,FullShader)] -> [Int] -> IO ()
+bindShaderLayer = zipWithM_ f
+  where 
+    f (l,fs) i = bindArrayBuffersLayer i l $ _vaoVBO $ _shaderVAO fs
+
 bindShaderBuffers :: [FullShader] -> [Int] -> IO ()
 bindShaderBuffers = zipWithM_ f
   where 
     f fs i = bindArrayBuffers i $ _vaoVBO $ _shaderVAO fs
 
+drawShaderLay :: Int -> FullShader -> Int -> IO ()
+{-# INLINE drawShaderLay #-}
+drawShaderLay l fs i = do 
+    currentProgram $= Just (_shaderProgram fs)
+    bindVertexArrayObject $= Just (_vao $ _shaderVAO fs)
+    case _shaderTexture fs of 
+        Just ShaderTexture{_textureObject = txo}
+            -> textureBinding Texture2D $= Just txo
+        _   -> return ()
+    glDrawArrays (marshalEPrimitiveMode $ _shaderDrawPrimitive fs) (fromIntegral $ l*stride*floatSize) (fromIntegral i)
+  where
+    stride = sum $ _vboAttribSizes $ _vaoVBO $ _shaderVAO fs
+
 drawShader :: FullShader -> Int -> IO ()
 {-# INLINE drawShader #-}
 drawShader fs i = do