From f1b67935b3857c014c9c4922fd9c8b558c4f9344 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Sat, 29 Oct 2022 21:13:21 +0200
Subject: [PATCH] Optimize `BoundingFrustum::Intersects(BoundingSphere)`

---
 Source/Engine/Core/Math/BoundingFrustum.cpp | 11 +++++++++++
 Source/Engine/Core/Math/BoundingFrustum.h   |  5 +----
 Source/Engine/Core/Math/Vector3.cs          |  3 +++
 Source/Engine/Core/Math/Vector3.h           |  2 +-
 4 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/Source/Engine/Core/Math/BoundingFrustum.cpp b/Source/Engine/Core/Math/BoundingFrustum.cpp
index 88f35b8ca..11601d8e5 100644
--- a/Source/Engine/Core/Math/BoundingFrustum.cpp
+++ b/Source/Engine/Core/Math/BoundingFrustum.cpp
@@ -178,3 +178,14 @@ ContainmentType BoundingFrustum::Contains(const BoundingSphere& sphere) const
         return ContainmentType::Contains;
     }
 }
+
+bool BoundingFrustum::Intersects(const BoundingSphere& sphere) const
+{
+    for (int32 i = 0; i < 6; i++)
+    {
+        const Real distance = Vector3::Dot(_planes[i].Normal, sphere.Center) + _planes[i].D;
+        if (distance < -sphere.Radius)
+            return false;
+    }
+    return true;
+}
diff --git a/Source/Engine/Core/Math/BoundingFrustum.h b/Source/Engine/Core/Math/BoundingFrustum.h
index 2ceed02ab..693db318e 100644
--- a/Source/Engine/Core/Math/BoundingFrustum.h
+++ b/Source/Engine/Core/Math/BoundingFrustum.h
@@ -235,10 +235,7 @@ public:
     /// </summary>
     /// <param name="sphere">The sphere.</param>
     /// <returns>True if the current BoundingFrustum intersects a BoundingSphere, otherwise false.</returns>
-    FORCE_INLINE bool Intersects(const BoundingSphere& sphere) const
-    {
-        return Contains(sphere) != ContainmentType::Disjoint;
-    }
+    bool Intersects(const BoundingSphere& sphere) const;
 
     /// <summary>
     /// Checks whether the current BoundingFrustum intersects a BoundingBox.
diff --git a/Source/Engine/Core/Math/Vector3.cs b/Source/Engine/Core/Math/Vector3.cs
index 1bf05ee8c..cb967f3f4 100644
--- a/Source/Engine/Core/Math/Vector3.cs
+++ b/Source/Engine/Core/Math/Vector3.cs
@@ -907,6 +907,7 @@ namespace FlaxEngine
         /// <param name="left">First source vector.</param>
         /// <param name="right">Second source vector.</param>
         /// <param name="result">When the method completes, contains the dot product of the two vectors.</param>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static void Dot(ref Vector3 left, ref Vector3 right, out Real result)
         {
             result = left.X * right.X + left.Y * right.Y + left.Z * right.Z;
@@ -918,6 +919,7 @@ namespace FlaxEngine
         /// <param name="left">First source vector.</param>
         /// <param name="right">Second source vector.</param>
         /// <returns>The dot product of the two vectors.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Real Dot(ref Vector3 left, ref Vector3 right)
         {
             return left.X * right.X + left.Y * right.Y + left.Z * right.Z;
@@ -929,6 +931,7 @@ namespace FlaxEngine
         /// <param name="left">First source vector.</param>
         /// <param name="right">Second source vector.</param>
         /// <returns>The dot product of the two vectors.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Real Dot(Vector3 left, Vector3 right)
         {
             return left.X * right.X + left.Y * right.Y + left.Z * right.Z;
diff --git a/Source/Engine/Core/Math/Vector3.h b/Source/Engine/Core/Math/Vector3.h
index d7390c499..179a4cbf7 100644
--- a/Source/Engine/Core/Math/Vector3.h
+++ b/Source/Engine/Core/Math/Vector3.h
@@ -622,7 +622,7 @@ public:
     }
 
     // dot product with another vector
-    static T Dot(const Vector3Base& a, const Vector3Base& b)
+    FORCE_INLINE static T Dot(const Vector3Base& a, const Vector3Base& b)
     {
         return a.X * b.X + a.Y * b.Y + a.Z * b.Z;
     }