🎮 Rework frequency-dependent absorption for sound

* No longer expose corresponding CVars since internal handling should suffice * the previous calculation for the air absorption factor for underwater environments incorrectly targeted 5 MHz instead of 5 kHz * AirAbsorptionGainHF is no longer adjusted since it should be determined by the preset
RigsOfRods · Nov 2, 2024 · 2dbc482 · 2dbc482
1 parent 3b8c016
commit 2dbc482
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Showing 6 changed files with 19 additions and 17 deletions.
diff --git a/source/main/Application.cpp b/source/main/Application.cpp
@@ -206,8 +206,6 @@ CVar* io_discord_rpc;
 CVar* io_invert_orbitcam;
 
 // Audio
-CVar* audio_air_absorption_factor;
-CVar* audio_air_absorption_gain_hf;
 CVar* audio_master_volume;
 CVar* audio_enable_creak;
 CVar* audio_enable_obstruction;

diff --git a/source/main/Application.h b/source/main/Application.h
@@ -453,8 +453,6 @@ extern CVar* io_discord_rpc;
 extern CVar* io_invert_orbitcam;
 
 // Audio
-extern CVar* audio_air_absorption_factor;
-extern CVar* audio_air_absorption_gain_hf;
 extern CVar* audio_master_volume;
 extern CVar* audio_enable_creak;
 extern CVar* audio_enable_obstruction;

diff --git a/source/main/audio/SoundManager.cpp b/source/main/audio/SoundManager.cpp
@@ -384,7 +384,7 @@ void SoundManager::Update(const float dt_sec)
         for(int hardware_index = 0; hardware_index < hardware_sources_num; hardware_index++)
         {
             // update air absorption factor
-            alSourcef(hardware_sources[hardware_index], AL_AIR_ABSORPTION_FACTOR, App::audio_air_absorption_factor->getFloat());
+            alSourcef(hardware_sources[hardware_index], AL_AIR_ABSORPTION_FACTOR, m_air_absorption_factor);
 
             this->UpdateObstructionFilter(hardware_index);
         }
@@ -433,8 +433,6 @@ void SoundManager::UpdateListenerEffectSlot(const float dt_sec)
 
     EFXEAXREVERBPROPERTIES current_environmental_properties = *m_listener_efx_reverb_properties;
 
-    current_environmental_properties.flAirAbsorptionGainHF = App::audio_air_absorption_gain_hf->getFloat();
-
     // early reflections panning, delay and strength
     if (App::audio_enable_reflection_panning->getBool() && m_efx_reverb_engine == EfxReverbEngine::EAXREVERB)
     {

diff --git a/source/main/audio/SoundManager.h b/source/main/audio/SoundManager.h
@@ -138,6 +138,17 @@ class SoundManager
      */
     void SetDopplerFactor(const float doppler_factor) const { alDopplerFactor(doppler_factor); }
 
+    /**
+     * Sets the air absorptions factor for the direct path of all sounds.
+     * @param air_absorption_factor Air absorption factor within the range of AL_AIR_ABSORPTION_FACTOR.
+     */
+    void SetAirAbsorptionFactor(const float air_absorption_factor) { m_air_absorption_factor = air_absorption_factor; }
+
+    /**
+     * @return current value set for the air absorption factor for the direct path of sounds
+     */
+    float GetAirAbsorptionFactor() const { return m_air_absorption_factor; }
+
     /**
      * Returns the number of currently used hardware sources. In a typical scenario,
      * this value changes dynamically.
@@ -233,6 +244,7 @@ class SoundManager
     bool                                            m_efx_is_available = false;
     ALuint                                          m_listener_slot = 0;
     ALuint                                          m_efx_outdoor_obstruction_lowpass_filter_id = 0;
+    float                                           m_air_absorption_factor = 1.0f;
     EfxReverbEngine                                 m_efx_reverb_engine = EfxReverbEngine::NONE;
     const EFXEAXREVERBPROPERTIES*                   m_listener_efx_reverb_properties = nullptr;
     std::map<std::string, EFXEAXREVERBPROPERTIES>   m_efx_properties_map;

diff --git a/source/main/audio/SoundScriptManager.cpp b/source/main/audio/SoundScriptManager.cpp
@@ -361,18 +361,16 @@ void SoundScriptManager::SetListenerEnvironment(Vector3 listener_position)
         {
             sound_manager->SetSpeedOfSound(1522.0f); // assume listener is in sea water (i.e. salt water)
             /*
-            According to the Francois-Garrison formula for frequency-dependant absorption at 5kHz in water
-            and assuming the Air Absorption Gain HF property of OpenAL is set to the minimum of 0.892,
-            the absorption factor should be ~11.25, which is just slightly above the maximum of 10.0.
-            */
-            App::audio_air_absorption_factor->setVal(10.0f);
-            App::audio_air_absorption_gain_hf->setVal(0.892f);
+             * According to the Francois-Garrison formula for frequency-dependant absorption at 5kHz in seawater,
+             * the absorption should be 0.334 db/km. OpenAL multiplies the Air Absorption Factor with an internal
+             * value of 0.05dB/m, so we need a factor of 0.00668f.
+             */
+            sound_manager->SetAirAbsorptionFactor(0.00668f);
         }
         else
         {
             sound_manager->SetSpeedOfSound(343.3f); // assume listener is in air at 20° celsius
-            App::audio_air_absorption_factor->setVal(1.0f);
-            App::audio_air_absorption_gain_hf->setVal(0.994f);
+            sound_manager->SetAirAbsorptionFactor(1.0f);
         }
 
         if (App::audio_enable_efx->getBool())

diff --git a/source/main/system/CVar.cpp b/source/main/system/CVar.cpp
@@ -149,8 +149,6 @@ void Console::cVarSetupBuiltins()
     App::io_discord_rpc          = this->cVarCreate("io_discord_rpc",          "Discord Rich Presence",      CVAR_ARCHIVE | CVAR_TYPE_BOOL,    "true");
     App::io_invert_orbitcam      = this->cVarCreate("io_invert_orbitcam",      "Invert orbit camera",        CVAR_ARCHIVE | CVAR_TYPE_BOOL,    "false");
 
-    App::audio_air_absorption_factor               = this->cVarCreate("audio_air_absorption_factor",               "Air absorption factor",                            CVAR_TYPE_FLOAT,   "1.0");
-    App::audio_air_absorption_gain_hf              = this->cVarCreate("audio_air_absorption_gain_hf",              "Air absorption Gain HF",                           CVAR_TYPE_FLOAT,   "0.994");
     App::audio_master_volume                       = this->cVarCreate("audio_master_volume",                       "Sound Volume",                      CVAR_ARCHIVE | CVAR_TYPE_FLOAT,   "1.0");
     App::audio_enable_creak                        = this->cVarCreate("audio_enable_creak",                        "Creak Sound",                       CVAR_ARCHIVE | CVAR_TYPE_BOOL,    "false");
     App::audio_enable_obstruction                  = this->cVarCreate("audio_enable_obstruction",                  "Obstruction of sounds",             CVAR_ARCHIVE | CVAR_TYPE_BOOL,    "false");