MOHAWK: MYST: Always redraw the sound receiver at constant speeds

Fixes the sound receiver display stopping for a little while
every second or so when keeping a direction button pressed.

2 files changed, 26 insertions, 11 deletions

diff --git a/engines/mohawk/myst_stacks/selenitic.cpp b/engines/mohawk/myst_stacks/selenitic.cpp
index a74f3318f9..a91b9952b3 100644
--- a/engines/mohawk/myst_stacks/selenitic.cpp
+++ b/engines/mohawk/myst_stacks/selenitic.cpp
@@ -61,7 +61,7 @@ Selenitic::Selenitic(MohawkEngine_Myst *vm) :
 
 	_soundReceiverCurrentSource = nullptr;
 	_soundReceiverPosition = nullptr;
-	_soundReceiverSpeed = 0;
+	_soundReceiverSpeed = kSoundReceiverSpeedStill;
 	_soundReceiverViewer = nullptr;
 	_soundReceiverRightButton = nullptr;
 	_soundReceiverLeftButton = nullptr;
@@ -669,7 +669,7 @@ void Selenitic::soundReceiverLeftRight(uint direction) {
 	_vm->_sound->stopEffect();
 
 	_soundReceiverDirection = direction;
-	_soundReceiverSpeed = 1;
+	_soundReceiverSpeed = kSoundReceiverSpeedSlow;
 	_soundReceiverStartTime = _vm->_system->getMillis();
 
 	soundReceiverUpdate();
@@ -951,7 +951,7 @@ void Selenitic::soundReceiver_run() {
 		if (_soundReceiverDirection) {
 			uint32 currentTime = _vm->_system->getMillis();
 
-			if (_soundReceiverSpeed == 50 && currentTime > _soundReceiverStartTime + 500) {
+			if (_soundReceiverSpeed == kSoundReceiverSpeedFast && currentTime > _soundReceiverStartTime + 500) {
 				soundReceiverIncreaseSpeed();
 				_soundReceiverStartTime = currentTime;
 			} else if (currentTime > _soundReceiverStartTime + 1000) {
@@ -959,8 +959,9 @@ void Selenitic::soundReceiver_run() {
 				_soundReceiverStartTime = currentTime;
 			}
 
-			if (currentTime > _soundReceiverStartTime + 100)
+			if (_soundReceiverSpeed > kSoundReceiverSpeedSlow || currentTime > _soundReceiverStartTime + 100) {
 				soundReceiverUpdate();
+			}
 		} else if (!_soundReceiverSigmaPressed) {
 			soundReceiverUpdateSound();
 		}
@@ -969,14 +970,20 @@ void Selenitic::soundReceiver_run() {
 
 void Selenitic::soundReceiverIncreaseSpeed() {
 	switch (_soundReceiverSpeed) {
-	case 1:
-		_soundReceiverSpeed = 5; // The original has this at 10
+	case kSoundReceiverSpeedStill:
+		// Should not happen
 		break;
-	case 5:
-		_soundReceiverSpeed = 10; // The original has this at 50 too fast!
+	case kSoundReceiverSpeedSlow:
+		_soundReceiverSpeed = kSoundReceiverSpeedNormal;
 		break;
-	case 10:
-		_soundReceiverSpeed = 13; // The original has this at 100, way too fast!
+	case kSoundReceiverSpeedNormal:
+		_soundReceiverSpeed = kSoundReceiverSpeedFast;
+		break;
+	case kSoundReceiverSpeedFast:
+		_soundReceiverSpeed = kSoundReceiverSpeedFaster;
+		break;
+	case kSoundReceiverSpeedFaster:
+		// Can't go faster
 		break;
 	}
 }
diff --git a/engines/mohawk/myst_stacks/selenitic.h b/engines/mohawk/myst_stacks/selenitic.h
index 1dc1505ec2..368f6f2566 100644
--- a/engines/mohawk/myst_stacks/selenitic.h
+++ b/engines/mohawk/myst_stacks/selenitic.h
@@ -74,6 +74,14 @@ private:
 	DECLARE_OPCODE(o_mazeRunnerRight_init);
 	DECLARE_OPCODE(o_mazeRunnerLeft_init);
 
+	enum SoundReceiverSpeed {
+		kSoundReceiverSpeedStill  = 0,
+		kSoundReceiverSpeedSlow   = 1,
+		kSoundReceiverSpeedNormal = 5,   // The original has this at 10
+		kSoundReceiverSpeedFast   = 10,  // The original has this at 50 too fast!
+		kSoundReceiverSpeedFaster = 13,  // The original has this at 100, way too fast!
+	};
+
 	void soundReceiver_run();
 
 	MystGameState::Selenitic &_state;
@@ -84,7 +92,7 @@ private:
 	MystAreaImageSwitch *_soundReceiverCurrentSource; // 112
 	uint16 *_soundReceiverPosition; // 116
 	uint16 _soundReceiverDirection; // 120
-	uint16 _soundReceiverSpeed; // 122
+	SoundReceiverSpeed _soundReceiverSpeed; // 122
 	uint32 _soundReceiverStartTime; //124
 	uint _soundReceiverNearBlinkCounter;
 	MystAreaImageSwitch *_soundReceiverViewer; // 128