From 6cd8db7b28b675f75ab22c2073832980d9f8d6a4 Mon Sep 17 00:00:00 2001
From: ehofman <ehofman>
Date: Tue, 17 Nov 2009 13:06:32 +0000
Subject: [PATCH] Set to default distance attenuation function but change the
 parameters a but for better sound effects (and most of all quieter sounds at
 greta distance

---
 simgear/sound/sample_group.cxx    |  2 +-
 simgear/sound/soundmgr_openal.cxx | 10 +++-------
 simgear/sound/xmlsound.cxx        |  7 ++++---
 3 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/simgear/sound/sample_group.cxx b/simgear/sound/sample_group.cxx
index dfe8d756..bd1bf485 100644
--- a/simgear/sound/sample_group.cxx
+++ b/simgear/sound/sample_group.cxx
@@ -144,7 +144,7 @@ void SGSampleGroup::update( double dt ) {
 
                 ALboolean looping = sample->is_looping() ? AL_TRUE : AL_FALSE;
                 alSourcei( source, AL_LOOPING, looping );
-                alSourcef( source, AL_ROLLOFF_FACTOR, 1.0 );
+                alSourcef( source, AL_ROLLOFF_FACTOR, 0.3 );
                 alSourcei( source, AL_SOURCE_RELATIVE, AL_FALSE );
                 alSourcePlay( source );
                 testForALError("sample play");
diff --git a/simgear/sound/soundmgr_openal.cxx b/simgear/sound/soundmgr_openal.cxx
index ef4a8f15..b9e86488 100644
--- a/simgear/sound/soundmgr_openal.cxx
+++ b/simgear/sound/soundmgr_openal.cxx
@@ -133,13 +133,9 @@ void SGSoundMgr::init() {
     alDopplerFactor(1.0);
     alDopplerVelocity(340.3);   // speed of sound in meters per second.
 
-#if 0
-    if ( alIsExtensionPresent((const ALchar*)"EXT_exponent_distance") ) {
-        alDistanceModel(AL_EXPONENT_DISTANCE);
-    } else {
-        alDistanceModel(AL_INVERSE_DISTANCE);
-    }
-#endif
+    // gain = AL_REFERENCE_DISTANCE / (AL_REFERENCE_DISTANCE +
+    //        AL_ROLLOFF_FACTOR * (distance - AL_REFERENCE_DISTANCE));
+    alDistanceModel(AL_INVERSE_DISTANCE_CLAMPED);
 
     testForALError("listener initialization");
 
diff --git a/simgear/sound/xmlsound.cxx b/simgear/sound/xmlsound.cxx
index 79a57c7f..479e3123 100644
--- a/simgear/sound/xmlsound.cxx
+++ b/simgear/sound/xmlsound.cxx
@@ -174,9 +174,10 @@ SGXmlSound::init(SGPropertyNode *root, SGPropertyNode *node,
 
    }
 
-   float reference_dist = node->getDoubleValue("reference-dist", 500.0);
-   float max_dist = node->getDoubleValue("max-dist", 3000.0);
- 
+   // rule of thumb: make reference distance a 100th of the maximum distance.
+   float reference_dist = node->getDoubleValue("reference-dist", 60.0);
+   float max_dist = node->getDoubleValue("max-dist", 6000.0);
+
    //
    // set pitch properties
    //
-- 
2.39.5