Apply room rolloff factors even when Auxiliary Send Auto is off

This must've been based on a misunderstanding. The source and reverb room
rolloff factors are options to exaggerate *or replace* the automatic room
distance attenuation. Which means it needs to be able to apply without the
automatic room attenuation enabled. This may be why the room rolloff properties
still applied with AL_EFFECTSLOT_AUXILIARY_SEND_AUTO off in Generic Software,
assuming it wasn't a bug.

alc/alu.cpp

@@ -470,31 +470,27 @@ bool CalcEffectSlotParams(EffectSlot *slot, EffectSlot **sorted_slots, ContextBa
     slot->Target = props->Target;
     slot->EffectType = props->Type;
     slot->mEffectProps = props->Props;
-    /* If this effect slot's Auxiliary Send Auto is off, don't apply the
-     * automatic send adjustments based on source distance.
-     *
-     * NOTE: Generic Software applies the adjustments regardless of this
-     * setting. It doesn't seem to use the flag for anything, only the source's
-     * send filter gain auto flag affects this.
-     */
-    if(auto *reverbprops = std::get_if<ReverbProps>(&props->Props);
-        reverbprops && slot->AuxSendAuto)
+
+    slot->RoomRolloff = 0.0f;
+    slot->DecayTime = 0.0f;
+    slot->DecayLFRatio = 0.0f;
+    slot->DecayHFRatio = 0.0f;
+    slot->DecayHFLimit = false;
+    slot->AirAbsorptionGainHF = 1.0f;
+    if(auto *reverbprops = std::get_if<ReverbProps>(&props->Props))
     {
         slot->RoomRolloff = reverbprops->RoomRolloffFactor;
-        slot->DecayTime = reverbprops->DecayTime;
-        slot->DecayLFRatio = reverbprops->DecayLFRatio;
-        slot->DecayHFRatio = reverbprops->DecayHFRatio;
-        slot->DecayHFLimit = reverbprops->DecayHFLimit;
         slot->AirAbsorptionGainHF = reverbprops->AirAbsorptionGainHF;
-    }
-    else
-    {
-        slot->RoomRolloff = 0.0f;
-        slot->DecayTime = 0.0f;
-        slot->DecayLFRatio = 0.0f;
-        slot->DecayHFRatio = 0.0f;
-        slot->DecayHFLimit = false;
-        slot->AirAbsorptionGainHF = 1.0f;
+        /* If this effect slot's Auxiliary Send Auto is off, don't apply the
+         * automatic send adjustments based on source distance.
+         */
+        if(slot->AuxSendAuto)
+        {
+            slot->DecayTime = reverbprops->DecayTime;
+            slot->DecayLFRatio = reverbprops->DecayLFRatio;
+            slot->DecayHFRatio = reverbprops->DecayHFRatio;
+            slot->DecayHFLimit = reverbprops->DecayHFLimit;
+        }
     }
 
     EffectState *state{props->State.release()};
@@ -1525,33 +1521,24 @@ void CalcAttnSourceParams(Voice *voice, const VoiceProps *props, const ContextBa
     voice->mDirect.Buffer = Device->Dry.Buffer;
     std::array<EffectSlot*,MaxSendCount> SendSlots{};
     std::array<float,MaxSendCount> RoomRolloff{};
-    std::bitset<MaxSendCount> UseDryAttnForRoom{0};
     for(uint i{0};i < NumSends;i++)
     {
         SendSlots[i] = props->Send[i].Slot;
         if(!SendSlots[i] || SendSlots[i]->EffectType == EffectSlotType::None)
+        {
             SendSlots[i] = nullptr;
-        else if(SendSlots[i]->AuxSendAuto)
+            voice->mSend[i].Buffer = {};
+        }
+        else
         {
             /* NOTE: Contrary to the EFX docs, the effect's room rolloff factor
              * applies to the selected distance model along with the source's
              * room rolloff factor, not necessarily the inverse distance model.
-             *
-             * Generic Software also applies these rolloff factors regardless
-             * of any setting. It doesn't seem to use the effect slot's send
-             * auto for anything, though as far as I understand, it's supposed
-             * to control whether the send gets the same gain/gainhf as the
-             * direct path (excluding the filter).
              */
             RoomRolloff[i] = props->RoomRolloffFactor + SendSlots[i]->RoomRolloff;
-        }
-        else
-            UseDryAttnForRoom.set(i);
 
-        if(!SendSlots[i])
-            voice->mSend[i].Buffer = {};
-        else
             voice->mSend[i].Buffer = SendSlots[i]->Wet.Buffer;
+        }
     }
 
     /* Transform source to listener space (convert to head relative) */
@@ -1686,17 +1673,10 @@ void CalcAttnSourceParams(Voice *voice, const VoiceProps *props, const ContextBa
     std::array<GainTriplet,MaxSendCount> WetGain{};
     for(uint i{0};i < NumSends;i++)
     {
-        WetGainBase[i] = std::clamp(WetGainBase[i]*WetCone, props->MinGain, props->MaxGain) *
+        const auto gain = std::clamp(WetGainBase[i]*WetCone, props->MinGain, props->MaxGain) *
             context->mParams.Gain;
-        /* If this effect slot's Auxiliary Send Auto is off, then use the dry
-         * path distance and cone attenuation, otherwise use the wet (room)
-         * path distance and cone attenuation. The send filter is used instead
-         * of the direct filter, regardless.
-         */
-        const bool use_room{!UseDryAttnForRoom.test(i)};
-        const float gain{use_room ? WetGainBase[i] : DryGainBase};
         WetGain[i].Base = std::min(gain * props->Send[i].Gain, GainMixMax);
-        WetGain[i].HF = (use_room ? WetConeHF : ConeHF) * props->Send[i].GainHF;
+        WetGain[i].HF = WetConeHF * props->Send[i].GainHF;
         WetGain[i].LF = props->Send[i].GainLF;
     }
 
@@ -1730,7 +1710,8 @@ void CalcAttnSourceParams(Voice *voice, const VoiceProps *props, const ContextBa
             if(!SendSlots[i] || !(SendSlots[i]->DecayTime > 0.0f))
                 continue;
 
-            if(absorb > std::numeric_limits<float>::epsilon())
+            if(SendSlots[i]->AirAbsorptionGainHF < 1.0f
+                && absorb > std::numeric_limits<float>::epsilon())
                 WetGain[i].HF *= std::pow(SendSlots[i]->AirAbsorptionGainHF, absorb);
 
             const float DecayDistance{SendSlots[i]->DecayTime * SpeedOfSoundMetersPerSec};