From 93b494d4ae136f43193a5a2da7a355938517767e Mon Sep 17 00:00:00 2001
From: Aaron Franke <arnfranke@yahoo.com>
Date: Mon, 7 Dec 2020 01:40:46 -0500
Subject: Add Quaternion angle_to method

---
 .../mono/glue/GodotSharp/GodotSharp/Core/Quaternion.cs  | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

(limited to 'modules/mono/glue')

diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/Quaternion.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/Quaternion.cs
index b087b4c200..817103994a 100644
--- a/modules/mono/glue/GodotSharp/GodotSharp/Core/Quaternion.cs
+++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/Quaternion.cs
@@ -113,6 +113,23 @@ namespace Godot
             get { return Dot(this); }
         }
 
+        /// <summary>
+        /// Returns the angle between this quaternion and `to`.
+        /// This is the magnitude of the angle you would need to rotate
+        /// by to get from one to the other.
+        ///
+        /// Note: This method has an abnormally high amount
+        /// of floating-point error, so methods such as
+        /// <see cref="Mathf.IsZeroApprox"/> will not work reliably.
+        /// </summary>
+        /// <param name="to">The other quaternion.</param>
+        /// <returns>The angle between the quaternions.</returns>
+        public real_t AngleTo(Quaternion to)
+        {
+            real_t dot = Dot(to);
+            return Mathf.Acos(Mathf.Clamp(dot * dot * 2 - 1, -1, 1));
+        }
+
         /// <summary>
         /// Performs a cubic spherical interpolation between quaternions `preA`,
         /// this vector, `b`, and `postB`, by the given amount `t`.
-- 
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