a little refactoring

functional-core/app-update.sml

@@ -137,13 +137,11 @@ struct
     | SECOND {x1, y1, x2, y2} =>
         getSecondTriangleStageVector (x1, y1, x2, y2, drawVec)
 
-  fun update (model, mouseX, mouseY, inputMsg) =
+  local
-    let
     open DrawMessage
     open InputMessage
-    in
+
-      case inputMsg of
+    fun mouseMoveOrRelease (model, mouseX, mouseY) =
-        MOUSE_MOVE {x = mouseX, y = mouseY} =>
       let
         val (drawVec, _, _) = getClickPos
           (#clickPoints model, mouseX, mouseY, 1.0, 0.0, 0.0)
@@ -152,43 +150,32 @@ struct
       in
         (model, drawMsg, mouseX, mouseY)
       end
-      | MOUSE_LEFT_RELEASE =>
+
-          let
+    fun mouseLeftClick (model, mouseX, mouseY) =
-            val (drawVec, _, _) = getClickPos
-              (#clickPoints model, mouseX, mouseY, 1.0, 0.0, 0.0)
-            val drawVec = getTriangleStageVector (model, drawVec)
-            val drawMsg = DRAW_BUTTON drawVec
-          in
-            (model, drawMsg, mouseX, mouseY)
-          end
-      | MOUSE_LEFT_CLICK =>
       let
         val (buttonVec, hpos, vpos) = getClickPos
           (#clickPoints model, mouseX, mouseY, 0.0, 0.0, 1.0)
       in
         if Vector.length buttonVec > 0 then
-              (case #triangleStage model of
+          case #triangleStage model of
             NO_TRIANGLE =>
               let
                 val drawVec = getTriangleStageVector (model, buttonVec)
                 val drawMsg = DRAW_BUTTON drawVec
 
                 val newTriangleStage = FIRST {x1 = hpos, y1 = vpos}
-                     val model =
+                val model = AppType.withTriangleStage (model, newTriangleStage)
-                       AppType.withTriangleStage (model, newTriangleStage)
               in
                 (model, drawMsg, mouseX, mouseY)
               end
           | FIRST {x1, y1} =>
               let
-                     val drawVec =
+                val drawVec = getFirstTriangleStageVector (x1, y1, buttonVec)
-                       getFirstTriangleStageVector (x1, y1, buttonVec)
                 val drawMsg = DRAW_BUTTON drawVec
 
                 val newTriangleStage = SECOND
                   {x1 = x1, y1 = y1, x2 = hpos, y2 = vpos}
-                     val model =
+                val model = AppType.withTriangleStage (model, newTriangleStage)
-                       AppType.withTriangleStage (model, newTriangleStage)
               in
                 (model, drawMsg, mouseX, mouseY)
               end
@@ -201,15 +188,30 @@ struct
                 val drawMsg = DRAW_TRIANGLES_AND_RESET_BUTTONS drawVec
               in
                 (model, drawMsg, mouseX, mouseY)
-                   end)
+              end
         else
           (model, NO_DRAW, mouseX, mouseY)
       end
-      | RESIZE_WINDOW {width, height} => 
+
+    fun resizeWindow (model, mouseX, mouseY, width, height) =
       let
+        val low = Int.min (width, height)
+        val high = Int.min (width, height)
+
+        val difference = high - low
+        val offset = difference div 2
         val _ = print "resized window \n"
       in
         (model, NO_DRAW, mouseX, mouseY)
       end
+  in
+    fun update (model, mouseX, mouseY, inputMsg) =
+      case inputMsg of
+        MOUSE_MOVE {x = mouseX, y = mouseY} =>
+          mouseMoveOrRelease (model, mouseX, mouseY)
+      | MOUSE_LEFT_RELEASE => mouseMoveOrRelease (model, mouseX, mouseY)
+      | MOUSE_LEFT_CLICK => mouseLeftClick (model, mouseX, mouseY)
+      | RESIZE_WINDOW {width, height} =>
+          resizeWindow (model, mouseX, mouseY, width, height)
   end
 end

imperative-shell/app-draw.sml

@@ -94,6 +94,7 @@ struct
     end
 
   fun drawButton (buttonDrawObject: draw_object, buttonDrawLength) =
+    if buttonDrawLength > 0 then
       let
         val {vertexBuffer, program, ...} = buttonDrawObject
         val _ = Gles3.bindBuffer vertexBuffer
@@ -106,6 +107,8 @@ struct
       in
         ()
       end
+    else
+      ()
 
   fun initTriangles () =
     let
@@ -114,12 +117,7 @@ struct
       val {vertexBuffer, program, ...} = triangleDrawObject
 
       val _ = Gles3.bindBuffer vertexBuffer
-      val _ =
+      val _ = Gles3.bufferData (#[], 0, Gles3.STATIC_DRAW ())
-        Gles3.bufferData
-          ( #[]
-          , 0
-          , Gles3.STATIC_DRAW ()
-          )
       val _ = Gles3.vertexAttribPointer (0, 2, 2, 0)
       val _ = Gles3.enableVertexAttribArray 0
     in
@@ -136,15 +134,17 @@ struct
     end
 
   fun drawTriangles (triangleDrawObject: draw_object, triangleDrawLength) =
+    if triangleDrawLength > 0 then
       let
         val {vertexBuffer, program, ...} = triangleDrawObject
         val _ = Gles3.bindBuffer vertexBuffer
         val _ = Gles3.vertexAttribPointer (0, 2, 2, 0)
         val _ = Gles3.enableVertexAttribArray 0
         val _ = Gles3.useProgram program
-      val _ = Gles3.drawArrays
+        val _ = Gles3.drawArrays (Gles3.TRIANGLES (), 0, triangleDrawLength)
-        (Gles3.TRIANGLES (), 0, triangleDrawLength)
       in
         ()
       end
+    else
+      ()
 end