diff --git a/fcore/quad-tree.sml b/fcore/quad-tree.sml
index 71f8073..c29a918 100644
--- a/fcore/quad-tree.sml
+++ b/fcore/quad-tree.sml
@@ -548,7 +548,13 @@ struct
 
       (* based on triangle order formed by `Ndc.ltrbToVertexRgb` function *)
       val item = String.concatWith ",\n"
-        [x, ey, ex, ey, x, y, x, y, ex, ey, ex, y]
+        [ 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
+        ]
     in
       item :: acc
     end