Add 'prediction time' setting for cell/terrain pre-loading

apps/openmw/mwworld/scene.cpp

@@ -478,6 +478,7 @@ namespace MWWorld
     , mPreloadExteriorGrid(Settings::Manager::getBool("preload exterior grid", "Cells"))
     , mPreloadDoors(Settings::Manager::getBool("preload doors", "Cells"))
     , mPreloadFastTravel(Settings::Manager::getBool("preload fast travel", "Cells"))
+    , mPredictionTime(Settings::Manager::getFloat("prediction time", "Cells"))
     {
         mPreloader.reset(new CellPreloader(rendering.getResourceSystem(), physics->getShapeManager(), rendering.getTerrain(), rendering.getLandManager()));
         mPreloader->setWorkQueue(mRendering.getWorkQueue());
@@ -685,7 +686,7 @@ namespace MWWorld
         const MWWorld::ConstPtr player = MWBase::Environment::get().getWorld()->getPlayerPtr();
         osg::Vec3f playerPos = player.getRefData().getPosition().asVec3();
         osg::Vec3f moved = playerPos - mLastPlayerPos;
-        osg::Vec3f predictedPos = playerPos + moved / dt;
+        osg::Vec3f predictedPos = playerPos + moved / dt * mPredictionTime;
 
         if (mCurrentCell->isExterior())
             exteriorPositions.push_back(predictedPos);

apps/openmw/mwworld/scene.hpp

@@ -67,6 +67,7 @@ namespace MWWorld
             bool mPreloadExteriorGrid;
             bool mPreloadDoors;
             bool mPreloadFastTravel;
+            float mPredictionTime;
 
             osg::Vec3f mLastPlayerPos;
 

docs/source/reference/modding/settings/cells.rst

@@ -155,6 +155,19 @@ preload cell expiry delay
 The amount of time (in seconds) that a preloaded cell will stay in cache after it is no longer referenced or required,
 for example, after the player has moved away from a door without entering it.
 
+prediction time
+---------------
+
+:Type:		floating point
+:Range:		>=0
+:Default:	1
+
+The amount of time (in seconds) in the future to predict the player position for. This predicted position is used to preload any cells and/or distant terrain required at that position.
+
+This setting will only have an effect if 'preload enabled' is set or the 'distant terrain' in the Terrain section is set.
+
+Increasing this setting from its default may help if your computer/hard disk is too slow to preload in time and you see loading screens and/or lag spikes.
+
 cache expiry delay
 ------------------
 

files/settings-default.cfg

@@ -73,6 +73,9 @@ preload cell cache max = 20
 # How long to keep preloaded cells in cache after they're no longer referenced/required (in seconds)
 preload cell expiry delay = 5
 
+# The predicted position of the player N seconds in the future will be used for preloading cells and distant terrain
+prediction time = 1
+
 # How long to keep models/textures/collision shapes in cache after they're no longer referenced/required (in seconds)
 cache expiry delay = 5