ILLUSIONS: DUCKMAN: Implement MIDI music fading

(cherry picked from commit 056b303)

3 files changed, 46 insertions, 2 deletions

diff --git a/engines/illusions/duckman/scriptopcodes_duckman.cpp b/engines/illusions/duckman/scriptopcodes_duckman.cpp
index 5e4dab4667..ee4979a11a 100644
--- a/engines/illusions/duckman/scriptopcodes_duckman.cpp
+++ b/engines/illusions/duckman/scriptopcodes_duckman.cpp
@@ -640,7 +640,7 @@ void ScriptOpcodes_Duckman::opStopMidiMusic(ScriptThread *scriptThread, OpCall &
 void ScriptOpcodes_Duckman::opFadeMidiMusic(ScriptThread *scriptThread, OpCall &opCall) {
 	ARG_INT16(duration);
 	ARG_INT16(finalVolume);
-	// TODO _vm->fadeMidiMusic(2, finalVolume, duration, opCall._threadId);
+	_vm->_soundMan->fadeMidiMusic(finalVolume, duration, opCall._threadId);
 }
 
 void ScriptOpcodes_Duckman::opAddMenuChoice(ScriptThread *scriptThread, OpCall &opCall) {
diff --git a/engines/illusions/sound.cpp b/engines/illusions/sound.cpp
index d8b03169ea..6a62ee52c6 100644
--- a/engines/illusions/sound.cpp
+++ b/engines/illusions/sound.cpp
@@ -23,6 +23,7 @@
 #include "common/config-manager.h"
 #include "illusions/illusions.h"
 #include "illusions/sound.h"
+#include "illusions/time.h"
 #include "audio/mididrv.h"
 #include "audio/midiparser.h"
 
@@ -384,6 +385,15 @@ void SoundMan::stopMidiMusic() {
 	_midiPlayer->stop();
 }
 
+void SoundMan::fadeMidiMusic(int16 finalVolume, int16 duration, uint32 notifyThreadId) {
+	_midiMusicFader._active = true;
+	_midiMusicFader._notifyThreadId = notifyThreadId;
+	_midiMusicFader._startVolume = _midiMusicFader._currVolume;
+	_midiMusicFader._finalVolume = finalVolume;
+	_midiMusicFader._startTime = getCurrentTime();
+	_midiMusicFader._duration = duration;
+}
+
 void SoundMan::clearMidiMusicQueue() {
 	_midiMusicQueue.clear();
 }
@@ -467,7 +477,26 @@ void SoundMan::updateMidi() {
 		_midiMusicQueue.remove_at(0);
 		_midiPlayer->play(musicId);
 	}
-	// TODO Update music volume fading
+	updateMidiMusicFader();
+}
+
+void SoundMan::updateMidiMusicFader() {
+	if (_midiMusicFader._active) {
+		int16 currTime = getCurrentTime();
+		if (currTime - _midiMusicFader._startTime > _midiMusicFader._duration) {
+			_midiMusicFader._active = false;
+			currTime = _midiMusicFader._startTime + _midiMusicFader._duration;
+			if (_midiMusicFader._notifyThreadId) {
+				_vm->notifyThreadId(_midiMusicFader._notifyThreadId);
+				_midiMusicFader._notifyThreadId = 0;
+			}
+		}
+		const int16 elapsedTime = currTime - _midiMusicFader._startTime;
+		const int16 volumeDelta = _midiMusicFader._finalVolume - _midiMusicFader._startVolume;
+		const int masterMusicVolume = _vm->_mixer->getVolumeForSoundType(Audio::Mixer::kMusicSoundType);
+		_midiMusicFader._currVolume = _midiMusicFader._startVolume + (elapsedTime * volumeDelta / _midiMusicFader._duration);
+		_midiPlayer->setVolume(_midiMusicFader._currVolume * masterMusicVolume / 255);
+	}
 }
 
 void SoundMan::setMusicVolume(uint16 volume) {
diff --git a/engines/illusions/sound.h b/engines/illusions/sound.h
index 2669102b69..027228ef0b 100644
--- a/engines/illusions/sound.h
+++ b/engines/illusions/sound.h
@@ -112,6 +112,18 @@ protected:
 	bool _looping;
 };
 
+struct MidiMusicFader {
+	bool _active;
+	uint _flags;
+	int16 _currVolume;
+	int16 _startVolume;
+	int16 _finalVolume;
+	int16 _startTime;
+	int16 _duration;
+	uint32 _notifyThreadId;
+	MidiMusicFader() : _active(false), _currVolume(255) {}
+};
+
 class SoundMan {
 public:
 	SoundMan(IllusionsEngine *vm);
@@ -123,6 +135,7 @@ public:
 
 	void playMidiMusic(uint32 musicId);
 	void stopMidiMusic();
+	void fadeMidiMusic(int16 finalVolume, int16 duration, uint32 notifyThreadId);
 	void clearMidiMusicQueue();
 
 	uint16 getMusicVolume();
@@ -158,8 +171,10 @@ protected:
 	VoicePlayer *_voicePlayer;
 	SoundList _sounds;
 	Common::Array<uint32> _midiMusicQueue;
+	MidiMusicFader _midiMusicFader;
 	Sound *getSound(uint32 soundEffectId);
 	void updateMidi();
+	void updateMidiMusicFader();
 	uint16 calcAdjustedVolume(const Common::String &volumeConfigKey, uint16 volume);
 };