I see cats

res/shaders/vert.shader

@@ -7,6 +7,6 @@ out vec2 v_texCoord;
 
 void main()
 {
-  gl_Position = position;
+  gl_Position = vec4(position, 1);
-  v_texCoord = texCoord;
+  v_texCoord = vec2(texCoord.x, 1.0 - texCoord.y);
 }

src/Main.hs

@@ -170,16 +170,28 @@ main = do
       --   <*> pure 1
       -- GL.clearColor $= clearcol
 
+      -- clear buffers before drawing
+      -- GL.clear [GL.ColorBuffer]
+      
+      -- -- rebind everything neccessary for draw call
+      -- bind vao
+      --   -- (note the missing bindings to the vertex buffer and the attrib pointer)
+      -- bind ibo
+      -- bind sp
+
+      -- throw away previous errors
+      -- void $ get GL.errors
+
       incrementValue <- takeMVar increment
       redValue <- takeMVar red
       let newRed = redValue + incrementValue
 
       -- write data to the uniform
-      bind sp
       setUniform sp "u_color" (GL.Color4 newRed 0.5 0 1 :: GL.Color4 GL.GLfloat)
 
       -- the actual drawing happens here
       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)
 
@@ -192,6 +204,8 @@ main = do
       else
         putMVar increment incrementValue
 
+      -- make GL finish things up
+      -- GL.flush
       -- draw context on screen
       SDL.glSwapWindow window