From 0eb2e4f974835eaaec0d493c486e05b75af0b9fe Mon Sep 17 00:00:00 2001
From: Justin Lin <caterpillar@openhome.cc>
Date: Tue, 25 Feb 2020 10:30:12 +0800
Subject: [PATCH] add tri_circumcircle

---
 src/experimental/tri_circumcircle.scad | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 src/experimental/tri_circumcircle.scad

diff --git a/src/experimental/tri_circumcircle.scad b/src/experimental/tri_circumcircle.scad
new file mode 100644
index 00000000..4b561d3e
--- /dev/null
+++ b/src/experimental/tri_circumcircle.scad
@@ -0,0 +1,18 @@
+function tri_circumcircle(points) =
+   let(
+      p0 = points[0],
+      p1 = points[1],
+      p2 = points[2],
+      v0 = p1 - p0,
+      d0 = (p1 + p0) / 2 * v0,
+      v1 = p2 - p1,
+      d1 = (p2 + p1) / 2 * v1,
+      det = -cross(v0 , v1)
+   )
+   det == 0? undef : 
+             let(
+                 x = (d1 * v0[1] - d0 * v1[1]) / det,
+                 y = (d0 * v1[0] - d1 * v0[0]) / det,
+                 r = norm(p0 - [x,y])
+             )
+             [[x,y], r];
\ No newline at end of file