SCI32: Implement per-channel audio panning

Used by RAMA, in various places, starting with the refrigerator
at base camp after the cable car at the beginning of the game.

5 files changed, 45 insertions, 2 deletions

diff --git a/engines/sci/engine/kernel.h b/engines/sci/engine/kernel.h
index a712474983..7e576f5b98 100644
--- a/engines/sci/engine/kernel.h
+++ b/engines/sci/engine/kernel.h
@@ -440,6 +440,8 @@ reg_t kDoAudioPreload(EngineState *s, int argc, reg_t *argv);
 reg_t kDoAudioFade(EngineState *s, int argc, reg_t *argv);
 reg_t kDoAudioHasSignal(EngineState *s, int argc, reg_t *argv);
 reg_t kDoAudioSetLoop(EngineState *s, int argc, reg_t *argv);
+reg_t kDoAudioPan(EngineState *s, int argc, reg_t *argv);
+reg_t kDoAudioPanOff(EngineState *s, int argc, reg_t *argv);
 
 reg_t kRobot(EngineState *s, int argc, reg_t *argv);
 reg_t kRobotOpen(EngineState *s, int argc, reg_t *argv);
diff --git a/engines/sci/engine/kernel_tables.h b/engines/sci/engine/kernel_tables.h
index 884a499542..6a45241817 100644
--- a/engines/sci/engine/kernel_tables.h
+++ b/engines/sci/engine/kernel_tables.h
@@ -236,8 +236,8 @@ static const SciKernelMapSubEntry kDoAudio_subops[] = {
 	{ SIG_SINCE_SCI21MID, 17, MAP_CALL(DoAudioHasSignal),          "",                     NULL },
 	{ SIG_SINCE_SCI21MID, 18, MAP_EMPTY(DoAudioCritical),          "(i)",                  NULL },
 	{ SIG_SINCE_SCI21MID, 19, MAP_CALL(DoAudioSetLoop),            "iii(o)",               NULL },
-	{ SIG_SCI3,           20, MAP_DUMMY(DoAudioPan),               "",                     NULL },
-	{ SIG_SCI3,           21, MAP_DUMMY(DoAudioPanOff),            "",                     NULL },
+	{ SIG_SCI3,           20, MAP_CALL(DoAudioPan),                "ii(i)(iii)",           NULL },
+	{ SIG_SCI3,           21, MAP_CALL(DoAudioPanOff),             "i(i)(iii)",            NULL },
 	SCI_SUBOPENTRY_TERMINATOR
 };
 #endif
diff --git a/engines/sci/engine/ksound.cpp b/engines/sci/engine/ksound.cpp
index ad137566a2..ee4f8efd9a 100644
--- a/engines/sci/engine/ksound.cpp
+++ b/engines/sci/engine/ksound.cpp
@@ -466,6 +466,16 @@ reg_t kDoAudioSetLoop(EngineState *s, int argc, reg_t *argv) {
 	return s->r_acc;
 }
 
+reg_t kDoAudioPan(EngineState *s, int argc, reg_t *argv) {
+	g_sci->_audio32->kernelPan(argc, argv);
+	return s->r_acc;
+}
+
+reg_t kDoAudioPanOff(EngineState *s, int argc, reg_t *argv) {
+	g_sci->_audio32->kernelPanOff(argc, argv);
+	return s->r_acc;
+}
+
 reg_t kSetLanguage(EngineState *s, int argc, reg_t *argv) {
 	// This is used by script 90 of MUMG Deluxe from the main menu to toggle
 	// the audio language between English and Spanish.
diff --git a/engines/sci/sound/audio32.cpp b/engines/sci/sound/audio32.cpp
index 2f30f7dd79..2f7338ea63 100644
--- a/engines/sci/sound/audio32.cpp
+++ b/engines/sci/sound/audio32.cpp
@@ -1312,6 +1312,27 @@ void Audio32::kernelLoop(const int argc, const reg_t *const argv) {
 	setLoop(channelIndex, loop);
 }
 
+void Audio32::kernelPan(const int argc, const reg_t *const argv) {
+	Common::StackLock lock(_mutex);
+
+	const int16 channelIndex = findChannelByArgs(argc, argv, 1, argc == 3 ? argv[2] : NULL_REG);
+	const int16 pan = argv[0].toSint16();
+	if (channelIndex != kNoExistingChannel) {
+		setPan(channelIndex, pan);
+	} else {
+		warning("Attempt to pan a channel that does not exist");
+	}
+}
+
+void Audio32::kernelPanOff(const int argc, const reg_t *const argv) {
+	Common::StackLock lock(_mutex);
+
+	const int16 channelIndex = findChannelByArgs(argc, argv, 0, argc == 2 ? argv[1] : NULL_REG);
+	if (channelIndex != kNoExistingChannel) {
+		setPan(channelIndex, -1);
+	}
+}
+
 #pragma mark -
 #pragma mark Debugging
 
diff --git a/engines/sci/sound/audio32.h b/engines/sci/sound/audio32.h
index 8b8ec2a6b5..71f5883541 100644
--- a/engines/sci/sound/audio32.h
+++ b/engines/sci/sound/audio32.h
@@ -508,6 +508,14 @@ public:
 		setLoop(findChannelById(resourceId, soundNode), loop);
 	}
 
+	/**
+	 * Sets the stereo panning for the given channel.
+	 */
+	void setPan(const int16 channelIndex, const int16 pan) {
+		Common::StackLock lock(_mutex);
+		getChannel(channelIndex).pan = pan;
+	}
+
 private:
 	/**
 	 * The tick when audio was globally paused.
@@ -644,6 +652,8 @@ public:
 	reg_t kernelMixing(const int argc, const reg_t *const argv);
 	reg_t kernelFade(const int argc, const reg_t *const argv);
 	void kernelLoop(const int argc, const reg_t *const argv);
+	void kernelPan(const int argc, const reg_t *const argv);
+	void kernelPanOff(const int argc, const reg_t *const argv);
 
 #pragma mark -
 #pragma mark Debugging