diff --git a/src/voxel/_impl/_vx_contour_impl.scad b/src/voxel/_impl/_vx_contour_impl.scad
index 75aa7cad..b36ec0c4 100644
--- a/src/voxel/_impl/_vx_contour_impl.scad
+++ b/src/voxel/_impl/_vx_contour_impl.scad
@@ -1,11 +1,15 @@
-use <util/has.scad>;
+use <../../util/set/hashset.scad>;
+use <../../util/set/hashset_has.scad>;
+use <../../__comm__/_pt2_hash.scad>;
+
+hash = function(p) _pt2_hash(p);
 
 function _vx_contour_corner_value(pts, x, y) =
     let(
-        c1 = has(pts, [x, y - 1], sorted = true) || has(pts, [x - 1, y - 1], sorted = true) ? 1 : 0,
-        c2 = has(pts, [x - 1, y], sorted = true) || has(pts, [x - 1, y + 1], sorted = true) ? 2 : 0,
-        c3 = has(pts, [x, y + 1], sorted = true) || has(pts, [x + 1, y + 1], sorted = true) ? 4 : 0,
-        c4 = has(pts, [x + 1, y], sorted = true) || has(pts, [x + 1, y - 1], sorted = true) ? 8 : 0
+        c1 = hashset_has(pts, [x, y - 1], hash = hash) || hashset_has(pts, [x - 1, y - 1], hash = hash) ? 1 : 0,
+        c2 = hashset_has(pts, [x - 1, y], hash = hash) || hashset_has(pts, [x - 1, y + 1], hash = hash) ? 2 : 0,
+        c3 = hashset_has(pts, [x, y + 1], hash = hash) || hashset_has(pts, [x + 1, y + 1], hash = hash) ? 4 : 0,
+        c4 = hashset_has(pts, [x + 1, y], hash = hash) || hashset_has(pts, [x + 1, y - 1], hash = hash) ? 8 : 0
     )
     c1 + c2 + c3 + c4;
 
@@ -18,6 +22,13 @@ _vx_contour_dir_table = [
 function _vx_contour_dir(cr_value) = 
     lookup(cr_value, _vx_contour_dir_table);
 
+function _vx_contour(points) = 
+    let(
+        // always start from the left-bottom pt
+        fst = min(points) + [-1, -1]
+    )
+    _vx_contour_travel(hashset(points, hash = function(p) _pt2_hash(p)), fst, fst);
+
 _vx_contour_nxt_offset = [
     [1,  0],   // RIGHT
     [0, -1],   // DOWN
diff --git a/src/voxel/vx_contour.scad b/src/voxel/vx_contour.scad
index c92acc5e..f12767bf 100644
--- a/src/voxel/vx_contour.scad
+++ b/src/voxel/vx_contour.scad
@@ -9,12 +9,5 @@
 **/ 
 
 use <_impl/_vx_contour_impl.scad>;
-use <../util/sort.scad>;
 
-function vx_contour(points, sorted = false) = 
-    let(
-        // always start from the left-bottom pt
-        sortedXY = sorted ? points : sort(points, by = "vt"),
-        fst = sortedXY[0] + [-1, -1]
-    )
-    _vx_contour_travel(sortedXY, fst, fst);
\ No newline at end of file
+function vx_contour(points) = _vx_contour(points);
\ No newline at end of file
diff --git a/test/voxel/test_vx_contour.scad b/test/voxel/test_vx_contour.scad
index ab5d10a8..cb2232e1 100644
--- a/test/voxel/test_vx_contour.scad
+++ b/test/voxel/test_vx_contour.scad
@@ -4,8 +4,9 @@ use <voxel/vx_contour.scad>;
 module test_vx_contour() {
     echo("==== test_vx_contour ====");
 
-    expected = [[1, 0], [2, 0], [3, 0], [4, 0], [5, 0], [6, 0], [7, 0], [7, 1], [7, 2], [7, 3], [7, 4], [7, 5], [7, 6], [7, 7], [6, 7], [5, 7], [4, 7], [4, 6], [4, 5], [3, 5], [2, 5], [1, 5], [1, 4], [0, 4], [0, 3], [0, 2], [0, 1], [1, 1]];
+    expected = [[0, 1], [1, 1], [1, 0], [2, 0], [3, 0], [4, 0], [5, 0], [6, 0], [7, 0], [7, 1], [7, 2], [7, 3], [7, 4], [7, 5], [7, 6], [7, 7], [6, 7], [5, 7], [4, 7], [4, 6], [4, 5], [3, 5], [2, 5], [1, 5], [1, 4], [0, 4], [0, 3], [0, 2]];
     actual = vx_contour(vx_ascii("d"));
+
     assert(expected == actual);
 }