Add NavMesh Modifier Volume actor type

Source/Engine/Navigation/NavModifierVolume.cpp

@@ -0,0 +1,54 @@
+// Copyright (c) 2012-2021 Wojciech Figat. All rights reserved.
+
+#include "NavModifierVolume.h"
+#include "Engine/Level/Scene/Scene.h"
+#include "Engine/Serialization/Serialization.h"
+#if USE_EDITOR
+#include "Editor/Editor.h"
+#include "Editor/Managed/ManagedEditor.h"
+#include "NavMeshBuilder.h"
+#endif
+
+NavModifierVolume::NavModifierVolume(const SpawnParams& params)
+    : BoxVolume(params)
+{
+    _size = 100.0f;
+}
+
+void NavModifierVolume::Serialize(SerializeStream& stream, const void* otherObj)
+{
+    // Base
+    BoxVolume::Serialize(stream, otherObj);
+
+    SERIALIZE_GET_OTHER_OBJ(NavModifierVolume);
+
+    SERIALIZE_MEMBER(AgentsMask, AgentsMask.Mask);
+}
+
+void NavModifierVolume::Deserialize(DeserializeStream& stream, ISerializeModifier* modifier)
+{
+    // Base
+    BoxVolume::Deserialize(stream, modifier);
+
+    DESERIALIZE_MEMBER(AgentsMask, AgentsMask.Mask);
+}
+
+#if USE_EDITOR
+
+void NavModifierVolume::OnBoundsChanged(const BoundingBox& prevBounds)
+{
+    // Auto-rebuild modified navmesh area
+    if (IsDuringPlay() && IsActiveInHierarchy() && !Editor::IsPlayMode && Editor::Managed->CanAutoBuildNavMesh())
+    {
+        BoundingBox dirtyBounds;
+        BoundingBox::Merge(prevBounds, _box, dirtyBounds);
+        NavMeshBuilder::Build(GetScene(), dirtyBounds, ManagedEditor::ManagedEditorOptions.AutoRebuildNavMeshTimeoutMs);
+    }
+}
+
+Color NavModifierVolume::GetWiresColor()
+{
+    return Color::Red;
+}
+
+#endif