add star

src/polyhedra/geom_star.scad

@@ -0,0 +1,25 @@
+function star(outerRadius = 1, innerRadius =  0.381966, height = 0.5, n = 5) =
+    let(
+        right = 90,
+        thetaStep = 360 / n,
+        half_thetaStep = thetaStep / 2,
+        half_height = height / 2,
+        leng_star = n * 2,
+        points = concat(
+            [
+                for(i = [0:n - 1]) 
+                let(
+                    a = thetaStep * i + right,
+                    outerPoint = [outerRadius * cos(a), outerRadius * sin(a), 0],
+                    innerPoint = [innerRadius * cos(a + half_thetaStep), innerRadius * sin(a + half_thetaStep), 0]
+                )
+                each [outerPoint, innerPoint]
+            ],
+            [[0, 0, half_height], [0, 0, -half_height]]
+        ),
+        faces = [
+            for(i = [0:leng_star - 1]) 
+                each [[leng_star, (i + 1) % leng_star, i], [i, (i + 1) % leng_star, leng_star + 1]]
+        ]
+    )
+    [points, faces];

src/polyhedra/star.scad

@@ -0,0 +1,6 @@
+use <geom_star.scad>;
+
+module star(outerRadius = 1, innerRadius =  0.381966, height = 0.5, n = 5) {
+    points_faces = star(outerRadius, innerRadius, height, n);
+    polyhedron(points_faces[0], points_faces[1]);
+}