get initial renderer to run

renderer-tutorial.cabal

@@ -32,5 +32,6 @@ executable renderer-tutorial
                      , VertexArray
                      , IndexBuffer
                      , Shader
+                     , Renderer
   hs-source-dirs:      src
   default-language:    Haskell2010

src/IndexBuffer.hs

@@ -17,7 +17,7 @@ data IndexBuffer a = IndexBuffer
   { iBufId    :: GL.BufferObject -- buffer id
   , iBufSize  :: GL.GLsizeiptr   -- size of data
   , iBufData  :: Ptr a           -- pointer to data
-  , iBufCount :: GL.GLuint       -- number of data elements
+  , iBufCount :: GL.GLint        -- number of data elements
   }
 
 -- instanciate typeclass from BufferClass and fill in missing implementations

src/Main.hs

@@ -37,6 +37,7 @@ import VertexArray
 import VertexBuffer
 import IndexBuffer
 import Shader
+import Renderer
 
 main :: IO ()
 main = do
@@ -169,11 +170,11 @@ main = do
       -- clear buffers before drawing
       GL.clear [GL.ColorBuffer]
       
-      -- rebind everything neccessary for draw call
+      -- -- rebind everything neccessary for draw call
-      bind vao
+      -- bind vao
-        -- (note the missing bindings to the vertex buffer and the attrib pointer)
+      --   -- (note the missing bindings to the vertex buffer and the attrib pointer)
-      bind ibo
+      -- bind ibo
-      bind sp
+      -- bind sp
 
       -- throw away previous errors
       -- void $ get GL.errors
@@ -186,7 +187,8 @@ main = do
       setUniform sp "u_color" (GL.Color4 newRed 0.5 0 1 :: GL.Color4 GL.GLfloat)
 
       -- the actual drawing happens here
-      GL.drawElements GL.Triangles 6 GL.UnsignedInt nullPtr
+      draw vao ibo sp
+      -- GL.drawElements GL.Triangles 6 GL.UnsignedInt nullPtr
       err <- get GL.errors
       when (not $ null err) (print $ "loop errors: " <> show err)
 

src/Renderer.hs

@@ -0,0 +1,21 @@
+module Renderer where
+
+import SDL (($=), get)
+
+import qualified Graphics.Rendering.OpenGL as GL
+
+import Foreign.Ptr
+
+-- internal imports
+
+import BindableClass
+import VertexArray
+import IndexBuffer
+import Shader
+
+draw :: VertexArray -> (IndexBuffer a) -> Shader -> IO ()
+draw va ib sp = do
+  bind sp
+  bind va
+  bind ib
+  GL.drawElements GL.Triangles (iBufCount ib) GL.UnsignedInt nullPtr