From 9ffe982efb479d6dbec77bb0fe4624caee1f2685 Mon Sep 17 00:00:00 2001
From: unknown <mlokogegelmlok@gmail.com>
Date: Mon, 29 Jun 2020 16:35:13 +0200
Subject: [PATCH] adding AngleTo method to Vec

---
 geometry.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/geometry.go b/geometry.go
index a98b78c..dbb5bc4 100644
--- a/geometry.go
+++ b/geometry.go
@@ -169,6 +169,12 @@ func (u Vec) Normal() Vec {
 	return Vec{-u.Y, u.X}
 }
 
+// Returns angle between two vectors
+func (u Vec) AngleTo(v Vec) {
+	u, v = u.Unit(), v.Unit()
+	return math.Acos(u.Dot(v))
+}
+
 // Dot returns the dot product of vectors u and v.
 func (u Vec) Dot(v Vec) float64 {
 	return u.X*v.X + u.Y*v.Y