add sort

all/dotSCAD.scad

@@ -70,6 +70,7 @@ include <util/split_str.scad>;
 include <util/sub_str.scad>;
 include <util/reverse.scad>;
 include <util/slice.scad>;
+include <util/sort.scad>;
 include <matrix/m_cumulate.scad>;
 include <matrix/m_mirror.scad>;
 include <matrix/m_rotation.scad>;

src/util/sort.scad

@@ -0,0 +1,19 @@
+function _sort(pts, i) = 
+    let(leng = len(pts))
+    leng <= 1 ? pts : 
+        let(
+            pivot = pts[0],
+            before = [for(j = 1; j < leng; j = j + 1) if(pts[j][i] < pivot[i]) pts[j]],
+            after =  [for(j = 1; j < leng; j = j + 1) if(pts[j][i] >= pivot[i]) pts[j]]
+        )
+        concat(_sort(before, i), [pivot], _sort(after, i));
+
+function sort(points, by, idx = -1) =
+    let(
+        i = by == "x" ? 0 : (
+            by == "y" ? 1 : (
+                by == "z" ? 2 : idx
+            )
+        )
+    )
+    _sort(points, i);

test/test_all.scad

@@ -68,6 +68,7 @@ include <util/test_sub_str.scad>;
 include <util/test_split_str.scad>;
 include <util/test_parse_number.scad>;
 include <util/test_slice.scad>;
+include <util/test_sort.scad>;
 
 // Pixel
 include <pixel/test_px_line.scad>;

test/util/test_sort.scad

@@ -0,0 +1,23 @@
+module test_sort() {
+    echo("==== test_sort ====");
+
+    include <unittest.scad>;
+    include <util/sort.scad>;
+
+    assertEqualPoints(
+        [[2, 0, 0], [5, 0, 0], [7, 0, 0], [9, 0, 0], [10, 0, 0]], 
+        sort([[10, 0, 0], [5, 0, 0], [7, 0, 0], [2, 0, 0], [9, 0, 0]], by = "x")
+    );
+
+    assertEqualPoints(
+        [[2, 0, 0], [5, 0, 0], [7, 0, 0], [9, 0, 0], [10, 0, 0]], 
+        sort([[10, 0, 0], [5, 0, 0], [7, 0, 0], [2, 0, 0], [9, 0, 0]], by = "idx", idx = 0)
+    );
+
+    assertEqualPoints(
+        [[0, 2, 0], [0, 5, 0], [0, 7, 0], [0, 9, 0], [0, 10, 0]], 
+        sort([[0, 10, 0], [0, 5, 0], [0, 7, 0], [0, 2, 0], [0, 9, 0]], by = "y")
+    );
+}
+
+test_sort();