Positional sound: Limit volume when closer than 1 node

Change OpenAL distance model from AL_INVERSE_DISTANCE to AL_INVERSE_DISTANCE_CLAMPED to avoid excessive volume when very close to the sound location, for example MTG doors, and MTG fire sounds which are combined at an average position and often located in air nodes. Because AL_REFERENCE_DISTANCE has been reduced to 1 node (the distance under which gain is clamped), multiply volume by the same factor to keep sound gains the same as before, since the gain is calculated as: gain = (AL_REFERENCE_DISTANCE / distance)
minetest · Sep 25, 2017 · a455297 · a455297 · HybridDog · Sep 27, 2017
1 parent d5a97e0
commit a455297
Showing 1 changed file with 10 additions and 4 deletions.
diff --git a/src/sound_openal.cpp b/src/sound_openal.cpp
@@ -36,6 +36,7 @@ with this program; ifnot, write to the Free Software Foundation, Inc.,
 	#include <AL/alc.h>
 	#include <AL/alext.h>
 #endif
+#include <cmath>
 #include <vorbis/vorbisfile.h>
 #include <cassert>
 #include "log.h"
@@ -332,7 +333,7 @@ class OpenALSoundManager: public ISoundManager
 			return;
 		}
 
-		alDistanceModel(AL_INVERSE_DISTANCE);
+		alDistanceModel(AL_INVERSE_DISTANCE_CLAMPED);
 
 		infostream<<"Audio: Initialized: OpenAL "<<alGetString(AL_VERSION)
 				<<", using "<<alcGetString(m_device, ALC_DEVICE_SPECIFIER)
@@ -405,7 +406,7 @@ class OpenALSoundManager: public ISoundManager
 		alSource3f(sound->source_id, AL_POSITION, 0, 0, 0);
 		alSource3f(sound->source_id, AL_VELOCITY, 0, 0, 0);
 		alSourcei(sound->source_id, AL_LOOPING, loop ? AL_TRUE : AL_FALSE);
-		volume = MYMAX(0.0, volume);
+		volume = std::max(0.0f, volume);
 		alSourcef(sound->source_id, AL_GAIN, volume);
 		alSourcef(sound->source_id, AL_PITCH, pitch);
 		alSourcePlay(sound->source_id);
@@ -427,9 +428,14 @@ class OpenALSoundManager: public ISoundManager
 		alSourcei(sound->source_id, AL_SOURCE_RELATIVE, false);
 		alSource3f(sound->source_id, AL_POSITION, pos.X, pos.Y, pos.Z);
 		alSource3f(sound->source_id, AL_VELOCITY, 0, 0, 0);
-		alSourcef(sound->source_id, AL_REFERENCE_DISTANCE, 30.0);
+		// Use alDistanceModel(AL_INVERSE_DISTANCE_CLAMPED) and set reference
+		// distance to clamp gain at <1 node distance, to avoid excessive
+		// volume when closer
+		alSourcef(sound->source_id, AL_REFERENCE_DISTANCE, 10.0f);
 		alSourcei(sound->source_id, AL_LOOPING, loop ? AL_TRUE : AL_FALSE);
-		volume = MYMAX(0.0, volume);
+		// Multiply by 3 to compensate for reducing AL_REFERENCE_DISTANCE from
+		// the previous value of 30 to the new value of 10
+		volume = std::max(0.0f, volume * 3.0f);
 		alSourcef(sound->source_id, AL_GAIN, volume);
 		alSourcef(sound->source_id, AL_PITCH, pitch);
 		alSourcePlay(sound->source_id);