SCI32: Implement SCI3-variant volume handling

Trying to find differences in Lighthouse's audio sample playback,
I discovered that SCI3 had its own variant of handling volumes and
sending this volume information back to game scripts. It is not
known if this fixes any sound bug.

2 files changed, 33 insertions, 3 deletions

diff --git a/engines/sci/sound/audio32.cpp b/engines/sci/sound/audio32.cpp
index 2f7338ea63..59ebc86bf3 100644
--- a/engines/sci/sound/audio32.cpp
+++ b/engines/sci/sound/audio32.cpp
@@ -1061,10 +1061,23 @@ void Audio32::setLoop(const int16 channelIndex, const bool loop) {
 #pragma mark Effects
 
 int16 Audio32::getVolume(const int16 channelIndex) const {
-	if (channelIndex < 0 || channelIndex >= _numActiveChannels) {
+	bool getGlobalVolume = false;
+	switch (getSciVersion()) {
+	case SCI_VERSION_3:
+		getGlobalVolume = (channelIndex == kAllChannels);
+		break;
+	default:
+		getGlobalVolume = (channelIndex < 0 || channelIndex >= _numActiveChannels);
+	}
+
+	if (getGlobalVolume) {
 		return (_mixer->getVolumeForSoundType(Audio::Mixer::kSFXSoundType) + 1) * kMaxVolume / Audio::Mixer::kMaxMixerVolume;
 	}
 
+	if (channelIndex < 0 || channelIndex >= _numActiveChannels) {
+		return -1;
+	}
+
 	Common::StackLock lock(_mutex);
 	return getChannel(channelIndex).volume;
 }
@@ -1266,7 +1279,13 @@ reg_t Audio32::kernelVolume(const int argc, const reg_t *const argv) {
 	Common::StackLock lock(_mutex);
 
 	const int16 volume = argc > 0 ? argv[0].toSint16() : -1;
-	const int16 channelIndex = findChannelByArgs(argc, argv, 1, argc > 2 ? argv[2] : NULL_REG);
+	int16 channelIndex;
+
+	if (getSciVersion() == SCI_VERSION_3 && argc < 2) {
+		channelIndex = kAllChannels;
+	} else {
+		channelIndex = findChannelByArgs(argc, argv, 1, argc > 2 ? argv[2] : NULL_REG);
+	}
 
 	if (volume != -1) {
 		setVolume(channelIndex, volume);
diff --git a/engines/sci/sound/soundcmd.cpp b/engines/sci/sound/soundcmd.cpp
index e8fd20d2e5..0bb295d41e 100644
--- a/engines/sci/sound/soundcmd.cpp
+++ b/engines/sci/sound/soundcmd.cpp
@@ -514,8 +514,19 @@ void SoundCommandParser::processUpdateCues(reg_t obj) {
 	if (musicSlot->isSample) {
 #ifdef ENABLE_SCI32
 		if (_soundVersion >= SCI_VERSION_2) {
-			const int position = g_sci->_audio32->getPosition(ResourceId(kResourceTypeAudio, musicSlot->resourceId), musicSlot->soundObj);
+			const ResourceId audioId = ResourceId(kResourceTypeAudio, musicSlot->resourceId);
+
+			if (getSciVersion() == SCI_VERSION_3) {
+				// In SSCI the volume is first set to -1 and then reset later if
+				// a sample is playing in the audio player, but since our audio
+				// code returns -1 for not-found samples, the extra check is not
+				// needed and we can just always set it to the return value of
+				// the getVolume call
+				const int16 volume = g_sci->_audio32->getVolume(audioId, musicSlot->soundObj);
+				writeSelectorValue(_segMan, musicSlot->soundObj, SELECTOR(vol), volume);
+			}
 
+			const int16 position = g_sci->_audio32->getPosition(audioId, musicSlot->soundObj);
 			if (position == -1) {
 				processStopSound(musicSlot->soundObj, true);
 			}