code function to turn work-in-progress triangle (of triangle_stage of) into a square, so user can see where they have already clicked

functional-core/app-type.sml

@@ -1,8 +1,8 @@
 signature APP_TYPE =
 sig
   datatype triangle_stage =
-    FIRST of {x1: Real32.real, y1: Real32.real}
-  | NO_TRIANGLE
+    NO_TRIANGLE
+  | FIRST of {x1: Real32.real, y1: Real32.real}
   | SECOND of
       {x1: Real32.real, x2: Real32.real, y1: Real32.real, y2: Real32.real}
 

functional-core/app-update.sml

@@ -17,6 +17,16 @@ struct
       end
   end
 
+  fun ltrbToVertex (left, top, right, bottom, r, g, b) =
+    #[ left, bottom, r, g, b
+     , right, bottom, r, g, b
+     , left, top, r, g, b
+
+     , left, top, r, g, b
+     , right, bottom, r, g, b
+     , right, top, r, g, b
+     ]
+
   local
     fun genClickPoints (windowWidth, windowHeight) =
       let
@@ -50,15 +60,7 @@ struct
               val bottom = (vpos - 5.0) / halfHeight
               val top = (vpos + 5.0) / halfHeight
 
-              val drawVec =
-                #[ left, bottom, r, g, b
-                 , right, bottom, r, g, b
-                 , left, top, r, g, b
-
-                 , left, top, r, g, b
-                 , right, bottom, r, g, b
-                 , right, top, r, g, b
-                 ]
+              val drawVec = ltrbToVertex (left, top, right, bottom, r, g, b)
 
               val hpos = hpos / halfWidth
               val vpos = vpos / halfHeight
@@ -91,6 +93,54 @@ struct
         (0, Real32.fromInt mouseX, Real32.fromInt mouseY, r, g, b)
   end
 
+  fun getTriangleStageVector (model: app_type, drawVec) =
+    case #triangleStage model of
+      NO_TRIANGLE => drawVec
+    | FIRST {x1, y1} =>
+        let
+          val halfWidth = Real32.fromInt (Constants.windowWidth div 2)
+          val halfHeight = Real32.fromInt (Constants.windowHeight div 2)
+
+          val x1px = x1 * halfWidth
+          val left = (x1px - 5.0) / halfWidth
+          val right = (x1px + 5.0) / halfWidth
+
+          val y1px = y1 * halfHeight
+          val top = (y1px + 5.0) / halfHeight
+          val bottom = (y1px - 5.0) / halfHeight
+
+          val firstVec = ltrbToVertex (left, top, right, bottom, 0.0, 0.0, 1.0)
+        in
+          Vector.concat [firstVec, drawVec]
+        end
+    | SECOND {x1, y1, x2, y2} => 
+        let
+          val halfWidth = Real32.fromInt (Constants.windowWidth div 2)
+          val halfHeight = Real32.fromInt (Constants.windowHeight div 2)
+
+          val x1px = x1 * halfWidth
+          val left = (x1px - 5.0) / halfWidth
+          val right = (x1px + 5.0) / halfWidth
+
+          val y1px = y1 * halfHeight
+          val top = (y1px + 5.0) / halfHeight
+          val bottom = (y1px - 5.0) / halfHeight
+
+          val firstVec = ltrbToVertex (left, top, right, bottom, 0.0, 0.0, 1.0)
+
+          val x2px = x2 * halfWidth
+          val left = (x2px - 5.0) / halfWidth
+          val right = (x2px + 5.0) / halfWidth
+
+          val y2px = y2 * halfHeight
+          val top = (y2px + 5.0) / halfHeight
+          val bottom = (y2px - 5.0) / halfHeight
+
+          val secVec = ltrbToVertex (left, top, right, bottom, 0.0, 0.0, 1.0)
+        in
+          Vector.concat [firstVec, secVec, drawVec]
+        end
+
   fun update (model, mouseX, mouseY, inputMsg) =
     let
       open DrawMessage