Add sequencer fade times

driver/amuseplay.cpp

@@ -113,7 +113,7 @@ struct AppCallback : boo::IApplicationCallback
         m_setupId = setupId;
         if (m_seq)
         {
-            m_seq->stopSong(true);
+            m_seq->stopSong(0.f, true);
             m_seq->kill();
         }
         m_seq = m_engine->seqPlay(m_groupId, setupId, nullptr);

include/amuse/Sequencer.hpp

@@ -40,6 +40,11 @@ class Sequencer : public Entity
     bool m_dieOnEnd = false; /**< Sequencer will be killed when current arrangement completes */
 
     float m_curVol = 1.f; /**< Current volume of sequencer */
+    float m_volFadeTime = 0.f;
+    float m_volFadeTarget = 0.f;
+    float m_volFadeStart = 0.f;
+    float m_stopFadeTime = 0.f;
+    float m_stopFadeBeginVol = 0.f;
 
     /** State of a single MIDI channel */
     struct ChannelState
@@ -135,10 +140,10 @@ public:
     void playSong(const unsigned char* arrData, bool dieOnEnd = true);
 
     /** Stop current MIDI arrangement */
-    void stopSong(bool now = false);
+    void stopSong(float fadeTime = 0.f, bool now = false);
 
     /** Set total volume of sequencer */
-    void setVolume(float vol);
+    void setVolume(float vol, float fadeTime = 0.f);
 
     /** Get current program number of channel */
     int8_t getChanProgram(int8_t chanId) const;

lib/Sequencer.cpp

@@ -149,12 +149,45 @@ Sequencer::ChannelState::ChannelState(Sequencer& parent, uint8_t chanId) : m_par
 void Sequencer::advance(double dt)
 {
     if (m_state == SequencerState::Playing)
+    {
+        if (m_stopFadeTime)
+        {
+            float step = dt / m_stopFadeTime * m_stopFadeBeginVol;
+            float vol = std::max(0.f, m_curVol - step);
+            if (vol == 0.f)
+            {
+                m_arrData = nullptr;
+                m_state = SequencerState::Interactive;
+                allOff(true);
+                m_stopFadeTime = 0.f;
+                return;
+            }
+            else
+            {
+                setVolume(vol);
+            }
+        }
+        else if (m_volFadeTime)
+        {
+            float step = dt / m_volFadeTime * std::fabsf(m_volFadeTarget - m_volFadeStart);
+            float vol;
+            if (m_curVol < m_volFadeTarget)
+                vol = std::min(m_volFadeTarget, m_curVol + step);
+            else if (m_curVol >= m_volFadeTarget)
+                vol = std::max(m_volFadeTarget, m_curVol - step);
+            if (vol == m_volFadeTarget)
+                m_volFadeTime = 0.f;
+            else
+                setVolume(vol);
+        }
+
         if (m_songState.advance(*this, dt))
         {
             m_arrData = nullptr;
             m_state = SequencerState::Interactive;
             allOff();
         }
+    }
 }
 
 size_t Sequencer::ChannelState::getVoiceCount() const
@@ -536,11 +569,19 @@ void Sequencer::playSong(const unsigned char* arrData, bool dieOnEnd)
     m_state = SequencerState::Playing;
 }
 
-void Sequencer::stopSong(bool now)
+void Sequencer::stopSong(float fadeTime, bool now)
 {
+    if (fadeTime == 0.f)
+    {
         allOff(now);
         m_arrData = nullptr;
         m_state = SequencerState::Interactive;
+    }
+    else
+    {
+        m_stopFadeTime = fadeTime;
+        m_stopFadeBeginVol = m_curVol;
+    }
 }
 
 void Sequencer::ChannelState::setVolume(float vol)
@@ -574,12 +615,21 @@ void Sequencer::ChannelState::setPan(float pan)
     }
 }
 
-void Sequencer::setVolume(float vol)
+void Sequencer::setVolume(float vol, float fadeTime)
 {
+    if (fadeTime == 0.f)
+    {
         m_curVol = vol;
         for (auto& chan : m_chanStates)
             if (chan)
                 chan->setVolume(chan->m_curVol);
+    }
+    else
+    {
+        m_volFadeTime = fadeTime;
+        m_volFadeTarget = vol;
+        m_volFadeStart = m_curVol;
+    }
 }
 
 int8_t Sequencer::getChanProgram(int8_t chanId) const