Server: reimplement Detour_IsGoalPolyReachable

The function is simple and everything for it has been reversed. Function has been rebuilt to make debugging easier, and confirmed to work as designed.

src/game/server/ai_utility.cpp

@@ -7,6 +7,7 @@
 #include "core/stdafx.h"
 #include "tier0/fasttimer.h"
 #include "tier1/cvar.h"
+#include "mathlib/bitvec.h"
 #include "engine/server/server.h"
 #include "public/edict.h"
 #include "game/server/detour_impl.h"
@@ -49,18 +50,54 @@ void Detour_FreeNavMeshByType(const NavMeshType_e navMeshType)
 
 //-----------------------------------------------------------------------------
 // Purpose: determines whether goal poly is reachable from agent poly
+//          (only checks static pathing)
 // input  : *nav - 
 //			fromRef - 
 //			goalRef - 
 //			animType - 
 // Output : value if reachable, false otherwise
 //-----------------------------------------------------------------------------
-uint8_t Detour_IsGoalPolyReachable(dtNavMesh* nav, dtPolyRef fromRef, dtPolyRef goalRef, TraverseAnimType_e animType)
+bool Detour_IsGoalPolyReachable(dtNavMesh* const nav, const dtPolyRef fromRef, 
+    const dtPolyRef goalRef, const TraverseAnimType_e animType)
 {
     if (navmesh_always_reachable.GetBool())
         return true;
 
-    return dtNavMesh__isPolyReachable(nav, fromRef, goalRef, animType);
+    // Same poly is always reachable.
+    if (fromRef == goalRef)
+        return true;
+
+    const dtMeshTile* fromTile = nullptr;
+    const dtMeshTile* goalTile = nullptr;
+    const dtPoly* fromPoly = nullptr;
+    const dtPoly* goalPoly = nullptr;
+
+    nav->getTileAndPolyByRefUnsafe(fromRef, &fromTile, &fromPoly);
+    nav->getTileAndPolyByRefUnsafe(goalRef, &goalTile, &goalPoly);
+
+    const unsigned short fromPolyGroupId = fromPoly->groupId;
+    const unsigned short goalPolyGroupId = goalPoly->groupId;
+
+    // If we don't have an anim type, then we shouldn't use the traversal tables
+    // since these are used for linking separate poly islands together (which 
+    // requires jumping or some form of animation). So instead, check if we are
+    // on the same poly island.
+    if (animType == ANIMTYPE_NONE)
+        return fromPolyGroupId == goalPolyGroupId;
+
+    const int* const traversalTable = nav->m_traversalTables[NavMesh_GetTraversalTableIndexForAnimType(animType)];
+
+    // Traversal table doesn't exist, attempt the path finding anyways (this is
+    // a bug in the NavMesh, rebuild it!).
+    if (!traversalTable)
+        return true;
+
+    const int polyGroupCount = nav->m_params.polyGroupCount;
+    const int fromPolyBitCell = traversalTable[calcTraversalTableCellIndex(polyGroupCount, fromPolyGroupId, goalPolyGroupId)];
+
+    // Check if the bit corresponding to our goal poly is set, if it isn't then
+    // there are no available traversal links from the current poly to the goal.
+    return fromPolyBitCell & BitVec_Bit(goalPolyGroupId);
 }
 
 //-----------------------------------------------------------------------------
@@ -160,6 +197,6 @@ static ConCommand navmesh_hotswap("navmesh_hotswap", Detour_HotSwap_f, "Hot swap
 ///////////////////////////////////////////////////////////////////////////////
 void VRecast::Detour(const bool bAttach) const
 {
-	DetourSetup(&dtNavMesh__isPolyReachable, &Detour_IsGoalPolyReachable, bAttach);
+	DetourSetup(&v_Detour_IsGoalPolyReachable, &Detour_IsGoalPolyReachable, bAttach);
 	DetourSetup(&v_Detour_LevelInit, &Detour_LevelInit, bAttach);
 }

src/game/server/detour_impl.h

@@ -9,9 +9,9 @@
 //-------------------------------------------------------------------------
 inline void(*v_Detour_LevelInit)(void);
 inline void(*v_Detour_FreeNavMesh)(dtNavMesh* mesh);
+inline bool(*v_Detour_IsGoalPolyReachable)(dtNavMesh* const nav, const dtPolyRef fromPoly, const dtPolyRef goalPoly, const TraverseAnimType_e animType);
 inline dtStatus(*dtNavMesh__Init)(dtNavMesh* thisptr, unsigned char* data, int flags);
 inline dtStatus(*dtNavMesh__addTile)(dtNavMesh* thisptr, unsigned char* data, dtMeshHeader* header, int dataSize, int flags, dtTileRef lastRef);
-inline uint8_t(*dtNavMesh__isPolyReachable)(dtNavMesh* thisptr, dtPolyRef poly_1, dtPolyRef poly_2, TraverseAnimType_e animType);
 
 
 constexpr const char* NAVMESH_PATH = "maps/navmesh/";
@@ -33,9 +33,9 @@ class VRecast : public IDetour
 	{
 		LogFunAdr("Detour_LevelInit", v_Detour_LevelInit);
 		LogFunAdr("Detour_FreeNavMesh", v_Detour_FreeNavMesh);
+		LogFunAdr("Detour_IsGoalPolyReachable", v_Detour_IsGoalPolyReachable);
 		LogFunAdr("dtNavMesh::Init", dtNavMesh__Init);
 		LogFunAdr("dtNavMesh::addTile", dtNavMesh__addTile);
-		LogFunAdr("dtNavMesh::isPolyReachable", dtNavMesh__isPolyReachable);
 		LogVarAdr("g_pNavMesh[ NavMeshType_e::NAVMESH_COUNT ]", g_pNavMesh);
 		LogVarAdr("g_pNavMeshQuery", g_pNavMeshQuery);
 	}
@@ -43,9 +43,9 @@ class VRecast : public IDetour
 	{
 		g_GameDll.FindPatternSIMD("48 89 5C 24 ?? 48 89 74 24 ?? 48 89 7C 24 ?? 55 41 54 41 55 41 56 41 57 48 8D AC 24 ?? ?? ?? ?? 48 81 EC ?? ?? ?? ?? 45 33 E4").GetPtr(v_Detour_LevelInit);
 		g_GameDll.FindPatternSIMD("40 53 48 83 EC 30 48 89 6C 24 ?? 48 8B D9").GetPtr(v_Detour_FreeNavMesh);
+		g_GameDll.FindPatternSIMD("48 89 6C 24 ?? 48 89 74 24 ?? 48 89 7C 24 ?? 41 56 49 63 F1").GetPtr(v_Detour_IsGoalPolyReachable);
 		g_GameDll.FindPatternSIMD("4C 89 44 24 ?? 53 41 56 48 81 EC ?? ?? ?? ?? 0F 10 11").GetPtr(dtNavMesh__Init);
 		g_GameDll.FindPatternSIMD("44 89 4C 24 ?? 41 55").GetPtr(dtNavMesh__addTile);
-		g_GameDll.FindPatternSIMD("48 89 6C 24 ?? 48 89 74 24 ?? 48 89 7C 24 ?? 41 56 49 63 F1").GetPtr(dtNavMesh__isPolyReachable);
 	}
 	virtual void GetVar(void) const
 	{

src/public/game/server/ai_agent.h

@@ -32,7 +32,8 @@ enum TraverseAnimType_e
 	ANIMTYPE_GOLIATH,
 
 	// Not an anim type!
-	ANIMTYPE_COUNT
+	ANIMTYPE_COUNT,
+	ANIMTYPE_NONE = -1 // No Animtype (appears after animtype count as we don't want to count it)
 };
 
 #endif // AI_AGENT_H