From 679e3aae6249ff32fa6b37f7b146880b7817a0ae Mon Sep 17 00:00:00 2001
From: Justin Lin <justin.sdk@gmail.com>
Date: Thu, 26 Aug 2021 18:49:42 +0800
Subject: [PATCH] add tri_is_ccw

---
 src/experimental/tri_is_ccw.scad | 6 ++++++
 1 file changed, 6 insertions(+)
 create mode 100644 src/experimental/tri_is_ccw.scad

diff --git a/src/experimental/tri_is_ccw.scad b/src/experimental/tri_is_ccw.scad
new file mode 100644
index 00000000..483cc132
--- /dev/null
+++ b/src/experimental/tri_is_ccw.scad
@@ -0,0 +1,6 @@
+function tri_is_ccw(p1, p2, p3) =
+    let(
+		area = (p2[0] - p1[0]) * (p3[1] - p1[1]) - (p3[0] - p1[0]) * (p2[1] - p1[1]),
+		_ = assert(area != 0, "points are collinear")
+	)
+	area > 0;
\ No newline at end of file