Add an option to ignore the app's speed of sound for reverb decay

3 files changed, 17 insertions, 4 deletions

diff --git a/Alc/ALc.c b/Alc/ALc.c
index 7fcac99d..901b5447 100644
--- a/Alc/ALc.c
+++ b/Alc/ALc.c
@@ -885,6 +885,10 @@ static void alc_init(void)
     if(str && (strcasecmp(str, "true") == 0 || strtol(str, NULL, 0) == 1))
         ZScale *= -1.0f;
 
+    str = getenv("__ALSOFT_REVERB_IGNORES_SOUND_SPEED");
+    if(str && (strcasecmp(str, "true") == 0 || strtol(str, NULL, 0) == 1))
+        OverrideReverbSpeedOfSound = AL_TRUE;
+
     ret = altss_create(&LocalContext, ReleaseThreadCtx);
     assert(ret == althrd_success);
 
@@ -2540,6 +2544,7 @@ static ALvoid InitContext(ALCcontext *Context)
     listener->Params.MetersPerUnit = listener->MetersPerUnit;
     listener->Params.DopplerFactor = 1.0f;
     listener->Params.SpeedOfSound = SPEEDOFSOUNDMETRESPERSEC;
+    listener->Params.ReverbSpeedOfSound = SPEEDOFSOUNDMETRESPERSEC;
 
     ATOMIC_INIT(&listener->Update, NULL);
     ATOMIC_INIT(&listener->FreeList, NULL);
diff --git a/Alc/ALu.c b/Alc/ALu.c
index dcd00c5b..a2ea4811 100644
--- a/Alc/ALu.c
+++ b/Alc/ALu.c
@@ -89,6 +89,9 @@ ALfloat ConeScale = 1.0f;
 /* Localized Z scalar for mono sources */
 ALfloat ZScale = 1.0f;
 
+/* Force default speed of sound for distance-related reverb decay. */
+ALboolean OverrideReverbSpeedOfSound = AL_FALSE;
+
 const aluMatrixf IdentityMatrixf = {{
     { 1.0f, 0.0f, 0.0f, 0.0f },
     { 0.0f, 1.0f, 0.0f, 0.0f },
@@ -312,6 +315,11 @@ static ALboolean CalcListenerParams(ALCcontext *Context)
 
     Listener->Params.DopplerFactor = props->DopplerFactor;
     Listener->Params.SpeedOfSound = props->SpeedOfSound * props->DopplerVelocity;
+    if(OverrideReverbSpeedOfSound)
+        Listener->Params.ReverbSpeedOfSound = SPEEDOFSOUNDMETRESPERSEC;
+    else
+        Listener->Params.ReverbSpeedOfSound = Listener->Params.SpeedOfSound *
+                                              Listener->Params.MetersPerUnit;
 
     Listener->Params.SourceDistanceModel = props->SourceDistanceModel;
     Listener->Params.DistanceModel = props->DistanceModel;
@@ -1105,8 +1113,8 @@ static void CalcAttnSourceParams(ALvoice *voice, const struct ALvoiceProps *prop
         else if(SendSlots[i]->Params.AuxSendAuto)
         {
             RoomRolloff[i] = SendSlots[i]->Params.RoomRolloff + props->RoomRolloffFactor;
-            DecayDistance[i] = SendSlots[i]->Params.DecayTime * Listener->Params.SpeedOfSound *
-                               Listener->Params.MetersPerUnit;
+            DecayDistance[i] = SendSlots[i]->Params.DecayTime *
+                               Listener->Params.ReverbSpeedOfSound;
             DecayHFDistance[i] = DecayDistance[i] * SendSlots[i]->Params.DecayHFRatio;
             if(SendSlots[i]->Params.DecayHFLimit)
             {
diff --git a/Alc/effects/reverb.c b/Alc/effects/reverb.c
index 455a433a..ee7954c4 100644
--- a/Alc/effects/reverb.c
+++ b/Alc/effects/reverb.c
@@ -1362,8 +1362,8 @@ static ALvoid ALreverbState_update(ALreverbState *State, const ALCcontext *Conte
     hfRatio = props->Reverb.DecayHFRatio;
     if(props->Reverb.DecayHFLimit && props->Reverb.AirAbsorptionGainHF < 1.0f)
         hfRatio = CalcLimitedHfRatio(hfRatio, props->Reverb.AirAbsorptionGainHF,
-                                     props->Reverb.DecayTime, Listener->Params.SpeedOfSound *
-                                     Listener->Params.MetersPerUnit);
+            props->Reverb.DecayTime, Listener->Params.ReverbSpeedOfSound
+        );
 
     /* Calculate the LF/HF decay times. */
     lfDecayTime = clampf(props->Reverb.DecayTime * props->Reverb.DecayLFRatio,