diff --git a/dotscape b/dotscape
index 3334a5e..a1a8b1f 100755
Binary files a/dotscape and b/dotscape differ
diff --git a/dotscape.mlb b/dotscape.mlb
index d1a5d41..9719888 100644
--- a/dotscape.mlb
+++ b/dotscape.mlb
@@ -7,10 +7,10 @@ ann
   "allowVectorExps true"
 in
   fcore/ndc.sml
-  fcore/graph-lines.sml
   cozette-sml/fonts/cozette-ascii.mlb
 end
 
+fcore/graph-lines.sml
 fcore/click-points.sml
 fcore/app-init.sml
 fcore/app-with.sml
diff --git a/fcore/graph-lines.sml b/fcore/graph-lines.sml
index 812788f..a2b93f6 100644
--- a/fcore/graph-lines.sml
+++ b/fcore/graph-lines.sml
@@ -15,22 +15,15 @@ struct
         val halfHeight = Real32.fromInt (windowHeight div 2)
 
         val curX = Vector.sub (xClickPoints, pos)
-        val curXNdc = (curX - halfWidth) / halfWidth
+        val minusX = (curX - halfWidth - 1.0) / halfWidth
+        val plusX = (curX - halfWidth + 1.0) / halfWidth
 
         val minY = Vector.sub (xClickPoints, 0)
         val minY = (~(minY - halfHeight)) / halfHeight
         val maxY = Vector.sub (xClickPoints, Vector.length xClickPoints - 1)
         val maxY = (~(maxY - halfHeight)) /halfHeight
 
-        val acc =
-            #[ curXNdc - 0.001, minY
-             , curXNdc + 0.001, minY
-             , curXNdc + 0.001, maxY
-
-             , curXNdc + 0.001, maxY
-             , curXNdc - 0.001, maxY
-             , curXNdc - 0.001, minY
-             ] :: acc
+        val acc = Ndc.ltrbToVertex (minusX, maxY, plusX, minY) :: acc
       in
         helpGenGraphLinesX
           (pos + 1, xClickPoints, yClickPoints, acc, windowWidth, windowHeight)
@@ -48,24 +41,15 @@ struct
         val halfHeight = Real32.fromInt halfHeight
 
         val curY = Vector.sub (yClickPoints, pos)
-        val curYNdc =(~(curY - halfHeight)) / halfHeight
+        val minusY = ~(curY - halfHeight - 1.0) / halfHeight
+        val plusY = ~(curY - halfHeight + 1.0) / halfHeight
 
         val minX = Vector.sub (xClickPoints, 0)
         val minX = (minX - halfWidth) / halfWidth
         val maxX = Vector.sub (xClickPoints, Vector.length xClickPoints - 1)
-
-        val _ = print ("maxX = " ^ Real32.toString maxX ^ "\n")
         val maxX = (maxX - halfWidth) / halfWidth
 
-        val acc =
-            #[ minX, curYNdc - 0.001
-             , minX, curYNdc + 0.001
-             , maxX, curYNdc + 0.001
-
-             , maxX, curYNdc + 0.001
-             , maxX, curYNdc - 0.001
-             , minX, curYNdc - 0.001 
-             ] :: acc
+        val acc = Ndc.ltrbToVertex (minX, plusY, maxX, minusY) :: acc
       in
         helpGenGraphLinesY
           (pos + 1, yClickPoints, xClickPoints, acc, windowWidth, windowHeight)