refactor to allow graph lines to be shown at start up

imperative-shell/app-draw.sml

@@ -41,11 +41,7 @@ struct
 
       val _ = Gles3.bindBuffer vertexBuffer
       val _ =
-        Gles3.bufferData
-          ( Constants.graphLines
-          , Vector.length Constants.graphLines
-          , Gles3.STATIC_DRAW ()
-          )
+        Gles3.bufferData (#[], 0, Gles3.STATIC_DRAW ())
       val _ = Gles3.vertexAttribPointer (0, 2, 2, 0)
       val _ = Gles3.enableVertexAttribArray 0
     in

imperative-shell/constants.sml

@@ -40,9 +40,4 @@ struct
     \{\n\
     \   FragColor = vec4(frag_col.x, frag_col.y, frag_col.z, 1.0f);\n\
     \}"
-
-  (* Todo: fix. Currently an empty vector which is not desired result,
-   * but changing vector dynamically (through resizing) works as desired. *)
-  val graphLines: Real32.real vector =
-    Vector.fromList []
 end

imperative-shell/event-loop.sml

@@ -14,7 +14,7 @@ struct
         loop (inputMailbox, drawMailbox, mouseX, mouseY, model)
       end
   in
-    fun update (inputMailbox, drawMailbox) =
+    fun update (inputMailbox, drawMailbox, initial) =
       loop
         ( inputMailbox
         , drawMailbox

imperative-shell/shell.sml

@@ -15,7 +15,13 @@ struct
       val _ = Glfw.makeContextCurrent window
       val _ = Gles3.loadGlad ()
 
+      val initialModel = AppType.getInitial (Constants.windowWidth, Constants.windowHeight)
+
+      val graphLines = #graphLines initialModel
       val graphDrawObject = AppDraw.initGraphLines ()
+      val _ =
+        AppDraw.uploadGraphLines (graphDrawObject, graphLines)
+
       val buttonDrawObject = AppDraw.initButton ()
       val triangleDrawObject = AppDraw.initTriangles ()
 
@@ -24,13 +30,14 @@ struct
 
       val _ = CML.spawn (fn () =>
         InputCallbacks.registerCallbacks (window, inputMailbox))
-      val _ = CML.spawn (fn () => EventLoop.update (inputMailbox, drawMailbox))
+      val _ = CML.spawn 
+        (fn () => EventLoop.update (inputMailbox, drawMailbox, initialModel))
       val _ = CML.spawn (fn () =>
         EventLoop.draw
           ( drawMailbox
           , window
           , graphDrawObject
-          , Vector.length Constants.graphLines div 2
+          , Vector.length graphLines div 2
           , buttonDrawObject
           , 0
           , triangleDrawObject