From 9450111ae6c972bea301a189044085eca7428e26 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Mon, 11 Oct 2021 14:32:34 +0200
Subject: [PATCH] Fix possible division by zero in `Plane.Normalize`

#648
---
 Source/Engine/Core/Math/Plane.cpp | 11 +++++++++++
 Source/Engine/Core/Math/Plane.cs  | 15 +++++++++------
 Source/Engine/Core/Math/Plane.h   |  9 ++-------
 3 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/Source/Engine/Core/Math/Plane.cpp b/Source/Engine/Core/Math/Plane.cpp
index 341f33a8c..da225870d 100644
--- a/Source/Engine/Core/Math/Plane.cpp
+++ b/Source/Engine/Core/Math/Plane.cpp
@@ -29,6 +29,17 @@ String Plane::ToString() const
     return String::Format(TEXT("{}"), *this);
 }
 
+void Plane::Normalize()
+{
+    const float length = Normal.Length();
+    if (!Math::IsZero(length))
+    {
+        const float rcp = 1.0f / length;
+        Normal *= rcp;
+        D *= rcp;
+    }
+}
+
 void Plane::Constlection(Matrix& result) const
 {
     const float x = Normal.X;
diff --git a/Source/Engine/Core/Math/Plane.cs b/Source/Engine/Core/Math/Plane.cs
index 79bf86bd8..4a4f96b82 100644
--- a/Source/Engine/Core/Math/Plane.cs
+++ b/Source/Engine/Core/Math/Plane.cs
@@ -214,12 +214,15 @@ namespace FlaxEngine
         /// </summary>
         public void Normalize()
         {
-            float magnitude = 1.0f / (float)Math.Sqrt(Normal.X * Normal.X + Normal.Y * Normal.Y + Normal.Z * Normal.Z);
-
-            Normal.X *= magnitude;
-            Normal.Y *= magnitude;
-            Normal.Z *= magnitude;
-            D *= magnitude;
+            float length = (float)Math.Sqrt(Normal.X * Normal.X + Normal.Y * Normal.Y + Normal.Z * Normal.Z);
+            if (!Mathf.IsZero(length))
+            {
+                float rcp = 1.0f / length;
+                Normal.X *= rcp;
+                Normal.Y *= rcp;
+                Normal.Z *= rcp;
+                D *= rcp;
+            }
         }
 
         /// <summary>
diff --git a/Source/Engine/Core/Math/Plane.h b/Source/Engine/Core/Math/Plane.h
index 2fbe7438c..448fc7573 100644
--- a/Source/Engine/Core/Math/Plane.h
+++ b/Source/Engine/Core/Math/Plane.h
@@ -97,14 +97,9 @@ public:
 public:
 
     /// <summary>
-    /// Changes the coefficients of the normal vector of the plane to make it of unit length
+    /// Changes the coefficients of the normal vector of the plane to make it of unit length.
     /// </summary>
-    void Normalize()
-    {
-        const float magnitude = Normal.InvLength();
-        Normal *= magnitude;
-        D *= magnitude;
-    }
+    void Normalize();
 
     void Negate()
     {