From 0551981b07e269592ff0da59f4ce5c8782b7f255 Mon Sep 17 00:00:00 2001
From: Justin Lin <justin.sdk@gmail.com>
Date: Thu, 15 Jul 2021 10:53:07 +0800
Subject: [PATCH] generalize shape

---
 examples/cutted_donut.scad | 29 +++++++++++++----------------
 1 file changed, 13 insertions(+), 16 deletions(-)

diff --git a/examples/cutted_donut.scad b/examples/cutted_donut.scad
index 582400f0..2e3a62ff 100644
--- a/examples/cutted_donut.scad
+++ b/examples/cutted_donut.scad
@@ -1,26 +1,23 @@
 use <ring_extrude.scad>;
 
 $fn = 96;
-arc_a = 120;
-arc_r = 15;
 inner_r = 12;
 number_of_turns = 1;
 
-cutted_donut(arc_a, arc_r, inner_r, number_of_turns) ;
 
-module cutted_donut(arc_a, arc_r, inner_r, number_of_turns) {
+arc_a = 120;
+arc_r = 15;
+shape = [
+	for(a = [0:360 / $fn:arc_a]) 
+		[arc_r * cos(a) , arc_r * sin(a)]
+];
 
-	arc_step = 360 / $fn;
-	for(init_a = [0, 180]) {
-		sh = [
-			for(a = [0:arc_step:arc_a]) 
-				[arc_r * cos(a + init_a) , arc_r * sin(a + init_a)]
-		];
-		ring_extrude(
-			sh, 
-			radius = arc_r + inner_r, 
-			twist = 180 + 360 * number_of_turns, 
-			angle = 360
-		);
+cutted_donut(shape, inner_r, number_of_turns) ;
+
+module cutted_donut(shape, inner_r, number_of_turns) {
+	r = arc_r + inner_r;
+	t = 180 + 360 * number_of_turns;
+	for(s = [shape, shape * -1]) {
+		ring_extrude(s, radius = r, twist = t, angle = 360);
 	}
 }