Closes #1123: Implement SlowFall magic effect

apps/openmw/mwworld/physicssystem.cpp

@@ -108,7 +108,7 @@ namespace MWWorld
         }
 
         static Ogre::Vector3 move(const MWWorld::Ptr &ptr, const Ogre::Vector3 &movement, float time,
-                                  bool isFlying, float waterlevel, OEngine::Physic::PhysicEngine *engine)
+                                  bool isFlying, float waterlevel, float slowFall, OEngine::Physic::PhysicEngine *engine)
         {
             const ESM::Position &refpos = ptr.getRefData().getPosition();
             Ogre::Vector3 position(refpos.pos);
@@ -229,7 +229,10 @@ namespace MWWorld
                 physicActor->setInertialForce(Ogre::Vector3(0.0f));
             else
             {
-                inertia.z += time*-627.2f;
+                float diff = time*-627.2f;
+                if (inertia.z < 0)
+                    diff *= slowFall;
+                inertia.z += diff;
                 physicActor->setInertialForce(inertia);
             }
             physicActor->setOnGround(isOnGround);
@@ -577,9 +580,10 @@ namespace MWWorld
 
                 float oldHeight = iter->first.getRefData().getPosition().pos[2];
 
+                const MWMechanics::MagicEffects& effects = iter->first.getClass().getCreatureStats(iter->first).getMagicEffects();
+
                 bool waterCollision = false;
-                if (iter->first.getClass().getCreatureStats(iter->first).getMagicEffects()
-                        .get(ESM::MagicEffect::WaterWalking).mMagnitude
+                if (effects.get(ESM::MagicEffect::WaterWalking).mMagnitude
                         && cell->hasWater()
                         && !world->isUnderwater(iter->first.getCell(),
                                                Ogre::Vector3(iter->first.getRefData().getPosition().pos)))
@@ -592,9 +596,12 @@ namespace MWWorld
                 if (waterCollision)
                     mEngine->dynamicsWorld->addCollisionObject(&object);
 
+                // 100 points of slowfall reduce gravity by 90% (this is just a guess)
+                float slowFall = 1-std::min(std::max(0.f, (effects.get(ESM::MagicEffect::SlowFall).mMagnitude / 100.f) * 0.9f), 0.9f);
+
                 Ogre::Vector3 newpos = MovementSolver::move(iter->first, iter->second, mTimeAccum,
                                                             world->isFlying(iter->first),
-                                                            waterlevel, mEngine);
+                                                            waterlevel, slowFall, mEngine);
 
                 if (waterCollision)
                     mEngine->dynamicsWorld->removeCollisionObject(&object);