From 86e6d3dac8bd542b04148521d81bde9d5d3a0695 Mon Sep 17 00:00:00 2001
From: elsid <elsid.mail@gmail.com>
Date: Sat, 7 Aug 2021 12:03:21 +0200
Subject: [PATCH] Do not cache navmesh when only object transformation is
 changed

This saves cache capacity when a scene contains objects contantly transforming
by scripts and causing changes in navmesh. The probability to get cache hit for
such states is almost zero because even a constant change in a single float
value may give up to 2^32 different states.
---
 components/detournavigator/asyncnavmeshupdater.cpp | 11 ++++++++++-
 components/detournavigator/makenavmesh.cpp         |  6 +++++-
 components/detournavigator/makenavmesh.hpp         |  8 +++++++-
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/components/detournavigator/asyncnavmeshupdater.cpp b/components/detournavigator/asyncnavmeshupdater.cpp
index 11de607456..a0c9cba613 100644
--- a/components/detournavigator/asyncnavmeshupdater.cpp
+++ b/components/detournavigator/asyncnavmeshupdater.cpp
@@ -18,6 +18,8 @@ namespace
 {
     using DetourNavigator::ChangeType;
     using DetourNavigator::TilePosition;
+    using DetourNavigator::UpdateType;
+    using DetourNavigator::ChangeType;
 
     int getManhattanDistance(const TilePosition& lhs, const TilePosition& rhs)
     {
@@ -35,6 +37,13 @@ namespace
                     result = std::min(result, getManhattanDistance(position, tile));
         return result;
     }
+
+    UpdateType getUpdateType(ChangeType changeType) noexcept
+    {
+        if (changeType == ChangeType::update)
+            return UpdateType::Temporary;
+        return UpdateType::Persistent;
+    }
 }
 
 namespace DetourNavigator
@@ -282,7 +291,7 @@ namespace DetourNavigator
         const auto offMeshConnections = mOffMeshConnectionsManager.get().get(job.mChangedTile);
 
         const auto status = updateNavMesh(job.mAgentHalfExtents, recastMesh.get(), job.mChangedTile, playerTile,
-            offMeshConnections, mSettings, navMeshCacheItem, mNavMeshTilesCache);
+            offMeshConnections, mSettings, navMeshCacheItem, mNavMeshTilesCache, getUpdateType(job.mChangeType));
 
         if (recastMesh != nullptr)
         {
diff --git a/components/detournavigator/makenavmesh.cpp b/components/detournavigator/makenavmesh.cpp
index 246f9d85b6..892f9c2dd2 100644
--- a/components/detournavigator/makenavmesh.cpp
+++ b/components/detournavigator/makenavmesh.cpp
@@ -506,7 +506,7 @@ namespace DetourNavigator
     UpdateNavMeshStatus updateNavMesh(const osg::Vec3f& agentHalfExtents, const RecastMesh* recastMesh,
         const TilePosition& changedTile, const TilePosition& playerTile,
         const std::vector<OffMeshConnection>& offMeshConnections, const Settings& settings,
-        const SharedNavMeshCacheItem& navMeshCacheItem, NavMeshTilesCache& navMeshTilesCache)
+        const SharedNavMeshCacheItem& navMeshCacheItem, NavMeshTilesCache& navMeshTilesCache, UpdateType updateType)
     {
         Log(Debug::Debug) << std::fixed << std::setprecision(2) <<
             "Update NavMesh with multiple tiles:" <<
@@ -562,6 +562,10 @@ namespace DetourNavigator
                 return navMeshCacheItem->lock()->removeTile(changedTile);
             }
 
+            if (updateType == UpdateType::Temporary)
+                return navMeshCacheItem->lock()->updateTile(changedTile, NavMeshTilesCache::Value(),
+                    makeNavMeshTileData(*prepared, offMeshConnections, agentHalfExtents, changedTile, settings));
+
             cachedNavMeshData = navMeshTilesCache.set(agentHalfExtents, changedTile, *recastMesh, std::move(prepared));
 
             if (!cachedNavMeshData)
diff --git a/components/detournavigator/makenavmesh.hpp b/components/detournavigator/makenavmesh.hpp
index 3e07341106..5b4169374b 100644
--- a/components/detournavigator/makenavmesh.hpp
+++ b/components/detournavigator/makenavmesh.hpp
@@ -47,10 +47,16 @@ namespace DetourNavigator
 
     NavMeshPtr makeEmptyNavMesh(const Settings& settings);
 
+    enum class UpdateType
+    {
+        Persistent,
+        Temporary
+    };
+
     UpdateNavMeshStatus updateNavMesh(const osg::Vec3f& agentHalfExtents, const RecastMesh* recastMesh,
         const TilePosition& changedTile, const TilePosition& playerTile,
         const std::vector<OffMeshConnection>& offMeshConnections, const Settings& settings,
-        const SharedNavMeshCacheItem& navMeshCacheItem, NavMeshTilesCache& navMeshTilesCache);
+        const SharedNavMeshCacheItem& navMeshCacheItem, NavMeshTilesCache& navMeshTilesCache, UpdateType updateType);
 }
 
 #endif