Merge pull request #1479 from akortunov/physics

Make physics framerate configurable

apps/openmw/mwphysics/physicssystem.cpp

@@ -1,5 +1,6 @@
 #include "physicssystem.hpp"
 
+#include <iostream>
 #include <stdexcept>
 
 #include <osg/Group>
@@ -683,6 +684,7 @@ namespace MWPhysics
         , mWaterHeight(0)
         , mWaterEnabled(false)
         , mParentNode(parentNode)
+        , mPhysicsDt(1.f / 60.f)
     {
         mResourceSystem->addResourceManager(mShapeManager.get());
 
@@ -695,6 +697,20 @@ namespace MWPhysics
         // Don't update AABBs of all objects every frame. Most objects in MW are static, so we don't need this.
         // Should a "static" object ever be moved, we have to update its AABB manually using DynamicsWorld::updateSingleAabb.
         mCollisionWorld->setForceUpdateAllAabbs(false);
+
+        // Check if a user decided to override a physics system FPS
+        const char* env = getenv("OPENMW_PHYSICS_FPS");
+        if (env)
+        {
+            std::string str(env);
+
+            float physFramerate = std::atof(env);
+            if (physFramerate > 0)
+            {
+                mPhysicsDt = 1.f / physFramerate;
+                std::cerr << "Warning: physics framerate was overriden (a new value is " << physFramerate << ")."  << std::endl;
+            }
+        }
     }
 
     PhysicsSystem::~PhysicsSystem()
@@ -1357,13 +1373,12 @@ namespace MWPhysics
         mMovementResults.clear();
 
         mTimeAccum += dt;
-        const float physicsDt = 1.f/60.0f;
 
         const int maxAllowedSteps = 20;
-        int numSteps = mTimeAccum / (physicsDt);
+        int numSteps = mTimeAccum / (mPhysicsDt);
         numSteps = std::min(numSteps, maxAllowedSteps);
 
-        mTimeAccum -= numSteps * physicsDt;
+        mTimeAccum -= numSteps * mPhysicsDt;
 
         if (numSteps)
         {
@@ -1412,7 +1427,7 @@ namespace MWPhysics
             bool positionChanged = false;
             for (int i=0; i<numSteps; ++i)
             {
-                position = MovementSolver::move(position, physicActor->getPtr(), physicActor, iter->second, physicsDt,
+                position = MovementSolver::move(position, physicActor->getPtr(), physicActor, iter->second, mPhysicsDt,
                                                 flying, waterlevel, slowFall, mCollisionWorld, mStandingCollisions);
                 if (position != physicActor->getPosition())
                     positionChanged = true;
@@ -1421,7 +1436,7 @@ namespace MWPhysics
             if (positionChanged)
                 mCollisionWorld->updateSingleAabb(physicActor->getCollisionObject());
 
-            float interpolationFactor = mTimeAccum / physicsDt;
+            float interpolationFactor = mTimeAccum / mPhysicsDt;
             osg::Vec3f interpolated = position * interpolationFactor + physicActor->getPreviousPosition() * (1.f - interpolationFactor);
 
             float heightDiff = position.z() - oldHeight;

apps/openmw/mwphysics/physicssystem.hpp

@@ -220,6 +220,8 @@ namespace MWPhysics
 
             osg::ref_ptr<osg::Group> mParentNode;
 
+            float mPhysicsDt;
+
             PhysicsSystem (const PhysicsSystem&);
             PhysicsSystem& operator= (const PhysicsSystem&);
     };