finish episode 12

README.md

@@ -4,12 +4,16 @@ This softwre aims to be an OpenGL renderer written in Haskell following the
 OpenGL tutorial by The Cherno
 (<https://www.youtube.com/playlist?list=PLlrATfBNZ98foTJPJ_Ev03o2oq3-GGOS2>).
 
+## Important notes
+
 There are some major deviations from the tutorial setup here as follows:
 
 * Code base is entirely written in Haskell, not C++
 * Instead of GLFW with GLEW I use SDL2 out of familiarity
 * Shaders are actually split into files per type, since IÄmnot willing to
         unleash Haskell list magic
+* Since I am using the OpenGL core profile from the start there is also a
+        vertex array creation call present from the start.
 
 I leave as many helpful comments as possible throughout the code, so feel free
 to peruse it.

src/Main.hs

@@ -67,8 +67,8 @@ main = do
   -- -- VERTICES
 
   -- first, create and bind a vertex array object
-  bo <- GL.genObjectName
-  GL.bindVertexArrayObject $= Just bo
+  vao <- GL.genObjectName
+  GL.bindVertexArrayObject $= Just vao
 
       -- define vertices (positions of the triangle corners) as List of Floats
   let vertexPositions =
@@ -155,6 +155,15 @@ main = do
 
   -- -- EVENTING AND DRAWING
 
+  -- -- UNBINDING ALL BUFFERS AND VERTEX ARRAYS
+
+  GL.bindVertexArrayObject $= Nothing
+  GL.bindBuffer GL.ArrayBuffer $= Nothing
+  GL.bindBuffer GL.ElementArrayBuffer $= Nothing
+  GL.currentProgram $= Nothing
+
+  -- -- LOOPING
+
   -- initial poll for events
   evs <- newMVar =<< SDL.pollEvents
 
@@ -175,6 +184,12 @@ main = do
       -- clear buffers before drawing
       GL.clear [GL.ColorBuffer]
       
+      -- rebind everything neccessary for draw call
+      GL.bindVertexArrayObject $= Just vao
+        -- (note the missing bindings to the vertex buffer and the attrib pointer)
+      GL.bindBuffer GL.ElementArrayBuffer $= Just ibo
+      GL.currentProgram $= Just sp
+
       -- throw away previous errors
       -- void $ get GL.errors