From 134260ba529ab57c8d014164ffc905cd65aa4c27 Mon Sep 17 00:00:00 2001
From: intolerantape <intolerantape@gmail.com>
Date: Sat, 11 Sep 2021 06:00:58 -0700
Subject: [PATCH] Added Vector*::Angle functions to C++

Directly ported the C# versions of the function.
---
 Source/Engine/Core/Math/Vector2.h | 14 ++++++++++++++
 Source/Engine/Core/Math/Vector3.h | 13 +++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/Source/Engine/Core/Math/Vector2.h b/Source/Engine/Core/Math/Vector2.h
index 11abd87b9..ea177a14a 100644
--- a/Source/Engine/Core/Math/Vector2.h
+++ b/Source/Engine/Core/Math/Vector2.h
@@ -614,6 +614,20 @@ public:
     /// <param name="v2">The third triangle vertex.</param>
     /// <returns>The triangle area.</returns>
     static float TriangleArea(const Vector2& v0, const Vector2& v1, const Vector2& v2);
+	
+	/// <summary>
+    /// Calculates the angle (in radians) between from and to. This is always the smallest value.
+    /// </summary>
+    /// <param name="from">The first vector.</param>
+    /// <param name="to">The second vector.</param>
+    /// <returns>The angle (in radians).</returns>
+    static float Angle(const Vector2& from, const Vector2& to)
+    {
+        const float dot = Math::Clamp(Dot(Normalize(from), Normalize(to)), -1.0f, 1.0f);
+        if (Math::Abs(dot) > (1.0f - ZeroTolerance))
+            return dot > 0.0f ? 0.0f : PI;
+        return Math::Acos(dot);
+    }
 };
 
 inline Vector2 operator+(float a, const Vector2& b)
diff --git a/Source/Engine/Core/Math/Vector3.h b/Source/Engine/Core/Math/Vector3.h
index 47dc6a593..1a83169d2 100644
--- a/Source/Engine/Core/Math/Vector3.h
+++ b/Source/Engine/Core/Math/Vector3.h
@@ -929,6 +929,19 @@ public:
     /// <returns>The triangle area.</returns>
     static float TriangleArea(const Vector3& v0, const Vector3& v1, const Vector3& v2);
 
+    /// <summary>
+    /// Calculates the angle (in radians) between from and to. This is always the smallest value.
+    /// </summary>
+    /// <param name="from">The first vector.</param>
+    /// <param name="to">The second vector.</param>
+    /// <returns>The angle (in radians).</returns>
+    static float Angle(const Vector3& from, const Vector3& to)
+    {
+        const float dot = Math::Clamp(Dot(Normalize(from), Normalize(to)), -1.0f, 1.0f);
+        if (Math::Abs(dot) > (1.0f - ZeroTolerance))
+            return dot > 0.0f ? 0.0f : PI;
+        return Math::Acos(dot);
+    }
 };
 
 inline Vector3 operator+(float a, const Vector3& b)