Use parent worldspace terrain when requested

apps/openmw/mwrender/landmanager.cpp

@@ -2,6 +2,7 @@
 
 #include <osg/Stats>
 
+#include <components/esm4/loadwrld.hpp>
 #include <components/resource/objectcache.hpp>
 #include <components/settings/values.hpp>
 
@@ -20,10 +21,17 @@ namespace MWRender
 
     osg::ref_ptr<ESMTerrain::LandObject> LandManager::getLand(ESM::ExteriorCellLocation cellIndex)
     {
+        const MWBase::World& world = *MWBase::Environment::get().getWorld();
+        if (ESM::isEsm4Ext(cellIndex.mWorldspace))
+        {
+            const ESM4::World* worldspace = world.getStore().get<ESM4::World>().find(cellIndex.mWorldspace);
+            if (!worldspace->mParent.isZeroOrUnset() && worldspace->mParentUseFlags & ESM4::World::UseFlag_Land)
+                cellIndex.mWorldspace = worldspace->mParent;
+        }
+
         if (const std::optional<osg::ref_ptr<osg::Object>> obj = mCache->getRefFromObjectCacheOrNone(cellIndex))
             return static_cast<ESMTerrain::LandObject*>(obj->get());
 
-        const MWBase::World& world = *MWBase::Environment::get().getWorld();
         osg::ref_ptr<ESMTerrain::LandObject> landObj = nullptr;
 
         if (ESM::isEsm4Ext(cellIndex.mWorldspace))

apps/openmw/mwrender/terrainstorage.cpp

@@ -1,6 +1,7 @@
 #include "terrainstorage.hpp"
 
 #include <components/esm3/loadland.hpp>
+#include <components/esm4/loadwrld.hpp>
 
 #include "../mwbase/environment.hpp"
 #include "../mwworld/esmstore.hpp"
@@ -33,6 +34,10 @@ namespace MWRender
 
         if (ESM::isEsm4Ext(cellLocation.mWorldspace))
         {
+            const ESM4::World* worldspace = esmStore.get<ESM4::World>().find(cellLocation.mWorldspace);
+            if (!worldspace->mParent.isZeroOrUnset() && worldspace->mParentUseFlags & ESM4::World::UseFlag_Land)
+                cellLocation.mWorldspace = worldspace->mParent;
+
             return esmStore.get<ESM4::Land>().search(cellLocation) != nullptr;
         }
         else
@@ -64,6 +69,10 @@ namespace MWRender
 
         if (ESM::isEsm4Ext(worldspace))
         {
+            const ESM4::World* worldRec = esmStore.get<ESM4::World>().find(worldspace);
+            if (!worldRec->mParent.isZeroOrUnset() && worldRec->mParentUseFlags & ESM4::World::UseFlag_Land)
+                worldspace = worldRec->mParent;
+
             const auto& lands = esmStore.get<ESM4::Land>().getLands();
             for (const auto& [landPos, _] : lands)
             {

components/esm4/loadwrld.cpp

@@ -185,6 +185,10 @@ void ESM4::World::load(ESM4::Reader& reader)
                 mWaterLevel = 0.f;
             }
         }
+
+        // TES4 doesn't define PNAM. Exact parent worldspace behavior needs research
+        if (!reader.hasFormVersion())
+            mParentUseFlags = 0xFFFF;
     }
 }
 

components/esm4/loadwrld.hpp

@@ -55,6 +55,18 @@ namespace ESM4
             WLD_NoGrass = 0x80 //                      No Grass
         };
 
+        enum UseFlags
+        {
+            UseFlag_Land = 0x01,
+            UseFlag_LOD = 0x02,
+            UseFlag_Map = 0x04,
+            UseFlag_Water = 0x08,
+            UseFlag_Climate = 0x10,
+            UseFlag_Imagespace = 0x20, // Unused in TES5
+            UseFlag_SkyCell = 0x40,
+            // cc9cii: 0x80 == needs water adjustment? Set for WastelandNV
+        };
+
         struct REFRcoord
         {
             ESM::FormId formId;
@@ -115,15 +127,7 @@ namespace ESM4
         // ----------------------
         ESM::FormId mMusic;
 
-        // 0x01 use Land data
+        std::uint16_t mParentUseFlags{ 0 };
-        // 0x02 use LOD data
-        // 0x04 use Map data
-        // 0x08 use Water data
-        // 0x10 use Climate data
-        // 0x20 use Image Space data (Climate for TES5)
-        // 0x40 use SkyCell (TES5)
-        // 0x80 needs water adjustment (this isn't for parent I think? FONV only set for wastelandnv)
-        std::uint16_t mParentUseFlags; // FO3/FONV
 
         // cache formId's of children (e.g. CELL, ROAD)
         std::vector<ESM::FormId> mCells;