Consolidate distance factor for 3D audio

The semantics of distance factor is now same for both OpenAL and Fmod.
The value is given in units per meter, and the default is 1.0.
This means that Panda units are understood to be meters by default.
For example, for feet one would have to set this value to 3.28.

panda/src/audio/audioManager.h

@@ -166,10 +166,10 @@ PUBLISHED:
                                                 PN_stdfloat *fx, PN_stdfloat *fy, PN_stdfloat *fz,
                                                 PN_stdfloat *ux, PN_stdfloat *uy, PN_stdfloat *uz);
  
-  // Control the "relative scale that sets the distance factor" units for 3D spacialized audio. Default is 1.0
-  // Fmod uses meters internally, so give a float in Units-per meter
-  // Don't know what Miles uses.
-  // Default is 1.0 which is adjust in panda to be feet.
+  // Control the "relative scale that sets the distance factor" units for 3D spacialized audio.
+  // This is a float in units-per-meter. Default value is 1.0, which means that Panda units
+  // are understood as meters; for e.g. feet, set 3.28.
+  // This factor is applied only to Fmod and OpenAL at the moment.
   virtual void audio_3d_set_distance_factor(PN_stdfloat factor);
   virtual PN_stdfloat audio_3d_get_distance_factor() const;
 

panda/src/audiotraits/fmodAudioManager.cxx

@@ -45,15 +45,8 @@ pset<FmodAudioManager *> FmodAudioManager::_all_managers;
 bool FmodAudioManager::_system_is_valid = false;
 
 
-//  This sets the distance factor for 3D audio to use feet. 
-//  FMOD uses meters by default.
-//  Since Panda use feet we need to compensate for that with a factor of 3.28
-//
-//  This can be overwritten.  You just need to call
-//  audio_3d_set_distance_factor(PN_stdfloat factor) and set your new factor.
-
 PN_stdfloat FmodAudioManager::_doppler_factor = 1;
-PN_stdfloat FmodAudioManager::_distance_factor = 3.28;
+PN_stdfloat FmodAudioManager::_distance_factor = 1;
 PN_stdfloat FmodAudioManager::_drop_off_factor = 1;
 
 
@@ -110,6 +103,8 @@ FmodAudioManager() {
   _up.y = 0;
   _up.z = 0;
 
+  _active = true;
+
   _saved_outputtype = FMOD_OUTPUTTYPE_AUTODETECT;
 
   if (_system == (FMOD::System *)NULL) {

panda/src/audiotraits/fmodAudioManager.h

@@ -132,9 +132,10 @@ class EXPCL_FMOD_AUDIO FmodAudioManager : public AudioManager {
                                                 PN_stdfloat *fx, PN_stdfloat *fy, PN_stdfloat *fz,
                                                 PN_stdfloat *ux, PN_stdfloat *uy, PN_stdfloat *uz);
           
-  // Control the "relative distance factor" for 3D spacialized audio. Default is 1.0
-  // Fmod uses meters internally, so give a float in Units-per meter
-  // Don't know what Miles uses.
+  // Control the "relative scale that sets the distance factor" units for 3D spacialized audio.
+  // This is a float in units-per-meter. Default value is 1.0, which means that Panda units
+  // are understood as meters; for e.g. feet, set 3.28.
+  // This factor is applied only to Fmod and OpenAL at the moment.
   virtual void audio_3d_set_distance_factor(PN_stdfloat factor);
   virtual PN_stdfloat audio_3d_get_distance_factor() const;
 

panda/src/audiotraits/fmodAudioSound.cxx

@@ -59,6 +59,9 @@ FmodAudioSound(AudioManager *manager, Filename file_name, bool positional) {
   _velocity.y = 0;
   _velocity.z = 0;
 
+  _min_dist = 1.0;
+  _max_dist = 1000000000.0;
+
   //Play Rate Variable
   _playrate = 1;
 

panda/src/audiotraits/openalAudioManager.cxx

@@ -97,7 +97,7 @@ OpenALAudioManager() {
   _is_valid = true;
 
   //Init 3D attributes
-  _distance_factor = 3.28;
+  _distance_factor = 1;
   _drop_off_factor = 1;
 
   _position[0] = 0;
@@ -664,11 +664,10 @@ audio_3d_get_listener_attributes(PN_stdfloat *px, PN_stdfloat *py, PN_stdfloat *
 ////////////////////////////////////////////////////////////////////
 //     Function: OpenALAudioManager::audio_3d_set_distance_factor
 //       Access: Public
-//  Description: Set units per foot
+//  Description: Set value in units per meter
 //               WARNING: OpenAL has no distance factor but we use this as a scale
 //                        on the min/max distances of sounds to preserve FMOD compatibility.
 //                        Also, adjusts the speed of sound to compensate for unit difference.
-//                        OpenAL's default speed of sound is 343.3 m/s == 1126.3 ft/s
 ////////////////////////////////////////////////////////////////////
 void OpenALAudioManager::
 audio_3d_set_distance_factor(PN_stdfloat factor) {
@@ -680,7 +679,7 @@ audio_3d_set_distance_factor(PN_stdfloat factor) {
   alGetError(); // clear errors
 
   if (_distance_factor>0) {
-    alSpeedOfSound(1126.3*_distance_factor);
+    alSpeedOfSound(343.3*_distance_factor);
     al_audio_errcheck("alSpeedOfSound()");
     // resets the doppler factor to the correct setting in case it was set to 0.0 by a distance_factor<=0.0
     alDopplerFactor(_doppler_factor);
@@ -701,7 +700,7 @@ audio_3d_set_distance_factor(PN_stdfloat factor) {
 ////////////////////////////////////////////////////////////////////
 //     Function: OpenALAudioManager::audio_3d_get_distance_factor
 //       Access: Public
-//  Description: Sets units per foot
+//  Description: Get value in units per meter
 ////////////////////////////////////////////////////////////////////
 PN_stdfloat OpenALAudioManager::
 audio_3d_get_distance_factor() const {

panda/src/audiotraits/openalAudioManager.h

@@ -88,10 +88,12 @@ class EXPCL_OPENAL_AUDIO OpenALAudioManager : public AudioManager {
                                                 PN_stdfloat *fx, PN_stdfloat *fy, PN_stdfloat *fz,
                                                 PN_stdfloat *ux, PN_stdfloat *uy, PN_stdfloat *uz);
 
-  // Control the "relative distance factor" for 3D spacialized audio in units-per-foot. Default is 1.0
-  // OpenAL has no distance factor but we use this as a scale
-  // on the min/max distances of sounds to preserve FMOD compatibility.
-  // Also, adjusts the speed of sound to compensate for unit difference.
+  // Control the "relative scale that sets the distance factor" units for 3D spacialized audio.
+  // This is a float in units-per-meter. Default value is 1.0, which means that Panda units
+  // are understood as meters; for e.g. feet, set 3.28.
+  // This factor is applied only to Fmod and OpenAL at the moment.
+  // OpenAL in fact has no distance factor like Fmod, but works with the speed of sound instead,
+  // so we use this factor to scale the speed of sound.
   virtual void audio_3d_set_distance_factor(PN_stdfloat factor);
   virtual PN_stdfloat audio_3d_get_distance_factor() const;
 

panda/src/audiotraits/openalAudioSound.cxx

@@ -53,7 +53,7 @@ OpenALAudioSound(OpenALAudioManager* manager,
   _balance(0),
   _play_rate(1.0),
   _positional(positional),
-  _min_dist(3.28f),
+  _min_dist(1.0f),
   _max_dist(1000000000.0f),
   _drop_off_factor(1.0f),
   _length(0.0),
@@ -745,7 +745,7 @@ set_3d_min_distance(PN_stdfloat dist) {
     _manager->make_current();
 
     alGetError(); // clear errors
-    alSourcef(_source,AL_REFERENCE_DISTANCE,_min_dist*_manager->audio_3d_get_distance_factor());
+    alSourcef(_source,AL_REFERENCE_DISTANCE,_min_dist);
     al_audio_errcheck("alSourcefv(_source,AL_REFERENCE_DISTANCE)");
   }
 }
@@ -774,7 +774,7 @@ set_3d_max_distance(PN_stdfloat dist) {
     _manager->make_current();
 
     alGetError(); // clear errors
-    alSourcef(_source,AL_MAX_DISTANCE,_max_dist*_manager->audio_3d_get_distance_factor());
+    alSourcef(_source,AL_MAX_DISTANCE,_max_dist);
     al_audio_errcheck("alSourcefv(_source,AL_MAX_DISTANCE)");
   }
 }