Fix foliage instance bounds calculations regression from 486781661e

Using matrix transformation doesn't work properly on some foliage.
Add `BoundingSphere.Transform` with `Transform` instead of `Matrix`

Source/Engine/Core/Math/BoundingSphere.cpp

@@ -4,6 +4,7 @@
 #include "BoundingBox.h"
 #include "Matrix.h"
 #include "Ray.h"
+#include "Transform.h"
 #include "../Types/String.h"
 
 const BoundingSphere BoundingSphere::Empty(Vector3(0, 0, 0), 0);
@@ -220,3 +221,9 @@ void BoundingSphere::Transform(const BoundingSphere& sphere, const Matrix& matri
     Vector3::Transform(sphere.Center, matrix, result.Center);
     result.Radius = sphere.Radius * matrix.GetScaleVector().GetAbsolute().MaxValue();
 }
+
+void BoundingSphere::Transform(const BoundingSphere& sphere, const ::Transform& transform, BoundingSphere& result)
+{
+    Vector3::Transform(sphere.Center, transform, result.Center);
+    result.Radius = sphere.Radius * transform.Scale.GetAbsolute().MaxValue();
+}

Source/Engine/Core/Math/BoundingSphere.cs

@@ -393,6 +393,30 @@ namespace FlaxEngine
             result.Radius = sphere.Radius * matrix.ScaleVector.Absolute.MaxValue;
         }
 
+        /// <summary>
+        /// Transforms the bounding sphere using the specified transformation.
+        /// </summary>
+        /// <param name="sphere">The sphere.</param>
+        /// <param name="transform">The transform.</param>
+        /// <remarks>The result transformed sphere.</remarks>
+        public static BoundingSphere Transform(BoundingSphere sphere, Transform transform)
+        {
+            Transform(ref sphere, ref transform, out var result);
+            return result;
+        }
+
+        /// <summary>
+        /// Transforms the bounding sphere using the specified transformation.
+        /// </summary>
+        /// <param name="sphere">The sphere.</param>
+        /// <param name="transform">The transform.</param>
+        /// <param name="result">The result transformed sphere.</param>
+        public static void Transform(ref BoundingSphere sphere, ref Transform transform, out BoundingSphere result)
+        {
+            Vector3.Transform(ref sphere.Center, ref transform, out result.Center);
+            result.Radius = sphere.Radius * transform.Scale.Absolute.MaxValue;
+        }
+
         /// <summary>
         /// Tests for equality between two objects.
         /// </summary>

Source/Engine/Core/Math/BoundingSphere.h

@@ -224,6 +224,14 @@ public:
     /// <param name="matrix">The matrix.</param>
     /// <param name="result">The result transformed sphere.</param>
     static void Transform(const BoundingSphere& sphere, const Matrix& matrix, BoundingSphere& result);
+
+    /// <summary>
+    /// Transforms the bounding sphere using the specified transformation.
+    /// </summary>
+    /// <param name="sphere">The sphere.</param>
+    /// <param name="transform">The transform.</param>
+    /// <param name="result">The result transformed sphere.</param>
+    static void Transform(const BoundingSphere& sphere, const ::Transform& transform, BoundingSphere& result);
 };
 
 template<>

Source/Engine/Foliage/Foliage.cpp

@@ -653,7 +653,7 @@ void Foliage::UpdateBounds()
     typeBounds.Resize(FoliageTypes.Count());
     for (int32 i = 0; i < typeBounds.Count(); i++)
     {
-        auto& type = FoliageTypes[i];
+        const auto& type = FoliageTypes[i];
         bool ready = type.IsReady();
         typeReady.Set(i, ready);
         if (ready)
@@ -661,16 +661,14 @@ void Foliage::UpdateBounds()
     }
 
     // Update bounds for all instances
-    Matrix foliageWorld, instanceLocal, instanceWorld;
-    GetLocalToWorldMatrix(foliageWorld);
+    Transform globalTransform = _transform, transform;
     for (auto i = Instances.Begin(); i.IsNotEnd(); ++i)
     {
         auto& instance = *i;
         if (typeReady.Get(instance.Type))
         {
-            instance.Transform.GetWorld(instanceLocal);
-            Matrix::Multiply(foliageWorld, instanceLocal, instanceWorld);
-            BoundingSphere::Transform(typeBounds[instance.Type], instanceWorld, instance.Bounds);
+            globalTransform.LocalToWorld(instance.Transform, transform);
+            BoundingSphere::Transform(typeBounds[instance.Type], transform, instance.Bounds);
         }
         else
         {
@@ -837,11 +835,8 @@ void Foliage::SetInstanceTransform(int32 index, const Transform& value)
     {
         BoundingSphere typeBounds;
         BoundingSphere::FromBox(type.Model->GetBox(), typeBounds);
-        Matrix foliageWorld, instanceLocal, instanceWorld;
-        GetLocalToWorldMatrix(foliageWorld);
-        instance.Transform.GetWorld(instanceLocal);
-        Matrix::Multiply(foliageWorld, instanceLocal, instanceWorld);
-        BoundingSphere::Transform(typeBounds, instanceWorld, instance.Bounds);
+        const Transform transform = _transform.LocalToWorld(instance.Transform);
+        BoundingSphere::Transform(typeBounds, transform, instance.Bounds);
     }
     else
     {
@@ -868,8 +863,7 @@ void Foliage::OnFoliageTypeModelLoaded(int32 index)
 
         BoundingSphere typeBounds;
         BoundingSphere::FromBox(type.Model->GetBox(), typeBounds);
-        Matrix foliageWorld, instanceLocal, instanceWorld;
-        GetLocalToWorldMatrix(foliageWorld);
+        Transform globalTransform = _transform, transform;
 
         for (auto i = Instances.Begin(); i.IsNotEnd(); ++i)
         {
@@ -877,9 +871,8 @@ void Foliage::OnFoliageTypeModelLoaded(int32 index)
             if (instance.Type != index)
                 continue;
 
-            instance.Transform.GetWorld(instanceLocal);
-            Matrix::Multiply(foliageWorld, instanceLocal, instanceWorld);
-            BoundingSphere::Transform(typeBounds, instanceWorld, instance.Bounds);
+            globalTransform.LocalToWorld(instance.Transform, transform);
+            BoundingSphere::Transform(typeBounds, transform, instance.Bounds);
 
 #if !FOLIAGE_USE_SINGLE_QUAD_TREE
             BoundingBox::FromSphere(instance.Bounds, box);