done converting coordinates to triangles for exporting (but I still need header and footer for that)

fcore/ndc.sml

@@ -12,14 +12,14 @@ struct
      , right, top
      ]
 
-  fun ltrbToVertexRgb (left, top, right, bottom, r, g, b) =
-    #[ left, bottom, r, g, b
-     , right, bottom, r, g, b
-     , left, top, r, g, b
+  fun ltrbToVertexRgb (startX, startY, endX, endY, r, g, b) =
+    #[ startX, endY, r, g, b
+     , endX, endY, r, g, b
+     , startX, startY, r, g, b
 
-     , left, top, r, g, b
-     , right, bottom, r, g, b
-     , right, top, r, g, b
+     , startX, startY, r, g, b
+     , endX, endY, r, g, b
+     , endX, startY, r, g, b
      ]
 
   fun fromPixelX (xpos, windowWidth, windowHeight) =

fcore/quad-tree.sml

@@ -553,7 +553,15 @@ struct
         , ") - halfHeight) / halfHeight)"
         ]
     in
-      x :: y :: ex :: ex :: y :: ey :: r :: g :: b :: acc
+      (* based on triangle order formed by `Ndc.ltrbToVertexRgb` function *)
+      x :: ey :: r :: g :: b ::
+      ex :: ey :: r :: g :: b ::
+      x :: y :: r :: g :: b ::
+
+      x :: y :: r :: g :: b ::
+      ex :: ey :: r :: g :: b ::
+      ex :: y :: r :: g :: b ::
+      acc
     end
 
   fun toExportString (squares, canvasWidth, canvasHeight) =