From 709c92714eb7b8fc0d9180223b40b49ad954fae0 Mon Sep 17 00:00:00 2001
From: Justin Lin <justin.sdk@gmail.com>
Date: Thu, 21 Jul 2022 17:17:52 +0800
Subject: [PATCH] add arc_great_circle

---
 src/experimental/arc_great_circle.scad | 12 ++++++++++++
 1 file changed, 12 insertions(+)
 create mode 100644 src/experimental/arc_great_circle.scad

diff --git a/src/experimental/arc_great_circle.scad b/src/experimental/arc_great_circle.scad
new file mode 100644
index 00000000..1f3433dc
--- /dev/null
+++ b/src/experimental/arc_great_circle.scad
@@ -0,0 +1,12 @@
+use <__comm__/__frags.scad>
+use <ptf/ptf_rotate.scad>
+
+function arc_great_circle(p1, p2, center = [0, 0, 0]) =
+    let(
+        radius = norm(p1 - center),
+        normal_vt = cross(p2, p1),
+        a = acos(p2 * p1 / pow(radius, 2)),
+        steps = round(a / (360 / __frags(radius))),
+        a_step = a / steps
+    )
+    [for(i = [0:steps]) ptf_rotate(p1, a_step * i, normal_vt)];
\ No newline at end of file