Fade out sound sources that are no longer close

* Handle culling of all sound sources in a separate function cull3DSound
* Add two new settings Sound::sfx fade in duration and Sound::sfx fade out duration

apps/openmw/mwsound/soundmanagerimp.cpp

@@ -33,6 +33,8 @@ namespace MWSound
     namespace
     {
         constexpr float sMinUpdateInterval = 1.0f / 30.0f;
+        constexpr float sSfxFadeInDuration = 1.0f;
+        constexpr float sSfxFadeOutDuration = 1.0f;
 
         WaterSoundUpdaterSettings makeWaterSoundUpdaterSettings()
         {
@@ -47,6 +49,17 @@ namespace MWSound
 
             return settings;
         }
+
+        float initialFadeVolume(float squaredDist, Sound_Buffer *sfx, Type type, PlayMode mode)
+        {
+            // If a sound is farther away than its maximum distance, start playing it with a zero fade volume.
+            // It can still become audible once the player moves closer.
+            const float maxDist = sfx->getMaxDist();
+            if (squaredDist > (maxDist * maxDist))
+                return 0.0f;
+
+            return 1.0;
+        }
     }
 
     // For combining PlayMode and Type flags
@@ -517,7 +530,8 @@ namespace MWSound
             return nullptr;
 
         const osg::Vec3f objpos(ptr.getRefData().getPosition().asVec3());
-        if ((mode & PlayMode::RemoveAtDistance) && (mListenerPos - objpos).length2() > 2000 * 2000)
+        const float squaredDist = (mListenerPos - objpos).length2();
+        if ((mode & PlayMode::RemoveAtDistance) && squaredDist > 2000 * 2000)
             return nullptr;
 
         // Look up the sound in the ESM data
@@ -548,6 +562,7 @@ namespace MWSound
                 params.mPos = objpos;
                 params.mVolume = volume * sfx->getVolume();
                 params.mBaseVolume = volumeFromType(type);
+                params.mFadeVolume = initialFadeVolume(squaredDist, sfx, type, mode);
                 params.mPitch = pitch;
                 params.mMinDistance = sfx->getMinDist();
                 params.mMaxDistance = sfx->getMaxDist();
@@ -576,12 +591,15 @@ namespace MWSound
         Sound_Buffer *sfx = mSoundBuffers.load(Misc::StringUtils::lowerCase(soundId));
         if(!sfx) return nullptr;
 
+        const float squaredDist = (mListenerPos - initialPos).length2();
+
         SoundPtr sound = getSoundRef();
         sound->init([&] {
             SoundParams params;
             params.mPos = initialPos;
             params.mVolume = volume * sfx->getVolume();
             params.mBaseVolume = volumeFromType(type);
+            params.mFadeVolume = initialFadeVolume(squaredDist, sfx, type, mode);
             params.mPitch = pitch;
             params.mMinDistance = sfx->getMinDist();
             params.mMaxDistance = sfx->getMaxDist();
@@ -830,6 +848,28 @@ namespace MWSound
         return {WaterSoundAction::DoNothing, nullptr};
     }
 
+    void SoundManager::cull3DSound(SoundBase *sound)
+    {
+        // Hard-coded distance of 2000.0f is from vanilla Morrowind
+        const float maxDist = sound->getDistanceCull() ? 2000.0f : sound->getMaxDistance();
+        const float squaredMaxDist = maxDist * maxDist;
+
+        const osg::Vec3f pos = sound->getPosition();
+        const float squaredDist = (mListenerPos - pos).length2();
+
+        if (squaredDist > squaredMaxDist)
+        {
+            // If getDistanceCull() is set, delete the sound after it has faded out
+            sound->setFade(sSfxFadeOutDuration, 0.0f, Play_FadeExponential | (sound->getDistanceCull() ? Play_StopAtFadeEnd : 0));
+        }
+        else
+        {
+            // Fade sounds back in once they are in range
+            sound->setFade(sSfxFadeInDuration, 1.0f, Play_FadeExponential);
+        }
+    }
+
+
     void SoundManager::updateSounds(float duration)
     {
         // We update active say sounds map for specific actors here
@@ -884,17 +924,12 @@ namespace MWSound
             {
                 Sound *sound = sndidx->first.get();
 
-                if(!ptr.isEmpty() && sound->getIs3D())
+                if (sound->getIs3D())
                 {
-                    const ESM::Position &pos = ptr.getRefData().getPosition();
-                    const osg::Vec3f objpos(pos.asVec3());
-                    sound->setPosition(objpos);
-
-                    if(sound->getDistanceCull())
-                    {
-                        if((mListenerPos - objpos).length2() > 2000*2000)
-                            mOutput->finishSound(sound);
-                    }
+                    if (!ptr.isEmpty())
+                        sound->setPosition(ptr.getRefData().getPosition().asVec3());
+
+                    cull3DSound(sound);
                 }
 
                 if(!sound->updateFade(duration) || !mOutput->isSoundPlaying(sound))
@@ -924,17 +959,15 @@ namespace MWSound
         {
             MWWorld::ConstPtr ptr = sayiter->first;
             Stream *sound = sayiter->second.get();
-            if(!ptr.isEmpty() && sound->getIs3D())
+            if (sound->getIs3D())
             {
-                MWBase::World *world = MWBase::Environment::get().getWorld();
-                const osg::Vec3f pos = world->getActorHeadTransform(ptr).getTrans();
-                sound->setPosition(pos);
-
-                if(sound->getDistanceCull())
+                if (!ptr.isEmpty())
                 {
-                    if((mListenerPos - pos).length2() > 2000*2000)
-                        mOutput->finishStream(sound);
+                    MWBase::World *world = MWBase::Environment::get().getWorld();
+                    sound->setPosition(world->getActorHeadTransform(ptr).getTrans());
                 }
+
+                cull3DSound(sound);
             }
 
             if(!sound->updateFade(duration) || !mOutput->isStreamPlaying(sound))

apps/openmw/mwsound/soundmanagerimp.hpp

@@ -34,6 +34,7 @@ namespace MWSound
 {
     class Sound_Output;
     struct Sound_Decoder;
+    class SoundBase;
     class Sound;
     class Stream;
 
@@ -111,6 +112,8 @@ namespace MWSound
         void advanceMusic(const std::string& filename);
         void startRandomTitle();
 
+        void cull3DSound(SoundBase *sound);
+
         void updateSounds(float duration);
         void updateRegionSound(float duration);
         void updateWaterSound();