SOUND: Expose attenuation function parameters. Use less aggressive de…

…faults.

The default, (0.5, 0, -1, 0) -> -6db and 0.5m ref distance, resulted in too strong attenuation.

src/game.cpp

@@ -2265,6 +2265,7 @@ void Game::ProcessNewSettings()
 
 	sound.SetVolume(settings.GetSoundVolume());
 	sound.SetMaxActiveSources(settings.GetMaxSoundSources());
+	sound.SetAttenuation(settings.GetSoundAttenuation());
 }
 
 void Game::ShowHUD(bool value)

src/settings.cpp

@@ -110,6 +110,11 @@ Settings::Settings() :
 {
 	resolution[0] = 800;
 	resolution[1] = 600;
+
+	sound_attenuation[0] =  0.9146065;
+	sound_attenuation[1] =  0.2729276;
+	sound_attenuation[2] = -0.2313740;
+	sound_attenuation[3] = -0.2884304;
 }
 
 void Settings::SetFailsafeSettings()
@@ -181,6 +186,10 @@ void Settings::Serialize(bool write, Config & config)
 	Param(config, write, section, "sky_time_speed", sky_time_speed);
 
 	config.get("sound", section);
+	Param(config, write, section, "attenuation_scale", sound_attenuation[0]);
+	Param(config, write, section, "attenuation_shift", sound_attenuation[1]);
+	Param(config, write, section, "attenuation_exponent", sound_attenuation[2]);
+	Param(config, write, section, "attenuation_offset", sound_attenuation[3]);
 	Param(config, write, section, "sources", sound_sources);
 	Param(config, write, section, "volume", sound_volume);
 	Param(config, write, section, "music_volume", music_volume);

src/settings.h

@@ -99,6 +99,12 @@ class Settings
 		return sound_sources;
 	}
 
+	// get sound attenuation[4] coefficients
+	const float * GetSoundAttenuation() const
+	{
+		return sound_attenuation;
+	}
+
 	bool GetMPH() const
 	{
 		return mph;
@@ -400,6 +406,7 @@ class Settings
 	float music_volume;
 	float sound_volume;
 	int sound_sources;
+	float sound_attenuation[4];
 	bool mph; //if false, KPH
 	std::string track;
 	int antialiasing; //0 or 1 mean off

src/sound/sound.cpp

@@ -151,6 +151,11 @@ Sound::Sound() :
 	samplers_num(0),
 	samplers_pause(true)
 {
+	attenuation[0] =  0.9146065;
+	attenuation[1] =  0.2729276;
+	attenuation[2] = -0.2313740;
+	attenuation[3] = -0.2884304;
+
 	sources.reserve(64);
 	samplers.reserve(64);
 }
@@ -255,6 +260,14 @@ void Sound::SetMaxActiveSources(size_t value)
 	max_active_sources = value;
 }
 
+void Sound::SetAttenuation(const float nattenuation[4])
+{
+	attenuation[0] = nattenuation[0];
+	attenuation[1] = nattenuation[1];
+	attenuation[2] = nattenuation[2];
+	attenuation[3] = nattenuation[3];
+}
+
 size_t Sound::AddSource(std::tr1::shared_ptr<SoundBuffer> buffer, float offset, bool is3d, bool loop)
 {
 	Source src;
@@ -441,11 +454,10 @@ void Sound::ProcessSources()
 				float len = relvec.Magnitude();
 				if (len < 0.1f) len = 0.1f;
 
-				// distance attenuation 1/r
-				float attenuation = 1.0f;
-				float mindist = 0.5f;
-				float dist = std::max(mindist, len);
-				float cgain = mindist / (mindist + attenuation * (dist - mindist));
+				// distance attenuation
+				// y = a * (x - b)^c + d
+				float cgain = attenuation[0] * powf(len - attenuation[1], attenuation[2]) + attenuation[3];
+				cgain = clamp(cgain, 0.0f, 1.0f);
 
 				// directional attenuation
 				// maximum at 0.75 (source on opposite side)

src/sound/sound.h

@@ -54,6 +54,9 @@ class Sound
 	// active sources limit can be adjusted at runtime
 	void SetMaxActiveSources(size_t value);
 
+	// attenuation: y = a * (x - b)^c + d
+	void SetAttenuation(const float attenuation[4]);
+
 	size_t AddSource(std::tr1::shared_ptr<SoundBuffer> buffer, float offset, bool is3d, bool loop);
 
 	void RemoveSource(size_t id);
@@ -87,6 +90,7 @@ class Sound
 	Vec3 listener_pos;
 	Vec3 listener_vel;
 	Quat listener_rot;
+	float attenuation[4];
 	float sound_volume;
 	bool initdone;
 	bool disable;