Partially revert "Use a different method for HRTF mixing"

The sound localization with virtual channel mixing was just too poor, so while
it's more costly to do per-source HRTF mixing, it's unavoidable if you want
good localization.

This is only partially reverted because having the virtual channel is still
beneficial, particularly with B-Format rendering and effect mixing which
otherwise skip HRTF processing. As before, the number of virtual channels can
potentially be customized, specifying more or less channels depending on the
system's needs.

1 files changed, 23 insertions, 2 deletions

diff --git a/Alc/mixer.c b/Alc/mixer.c
index 4a98ee8f..3f80434e 100644
--- a/Alc/mixer.c
+++ b/Alc/mixer.c
@@ -41,6 +41,20 @@
 extern inline void InitiatePositionArrays(ALuint frac, ALuint increment, ALuint *frac_arr, ALuint *pos_arr, ALuint size);
 
 
+static inline HrtfMixerFunc SelectHrtfMixer(void)
+{
+#ifdef HAVE_SSE
+    if((CPUCapFlags&CPU_CAP_SSE))
+        return MixHrtf_SSE;
+#endif
+#ifdef HAVE_NEON
+    if((CPUCapFlags&CPU_CAP_NEON))
+        return MixHrtf_Neon;
+#endif
+
+    return MixHrtf_C;
+}
+
 static inline MixerFunc SelectMixer(void)
 {
 #ifdef HAVE_SSE
@@ -165,6 +179,7 @@ static const ALfloat *DoFilters(ALfilterState *lpfilter, ALfilterState *hpfilter
 ALvoid MixSource(ALvoice *voice, ALsource *Source, ALCdevice *Device, ALuint SamplesToDo)
 {
     MixerFunc Mix;
+    HrtfMixerFunc HrtfMix;
     ResamplerFunc Resample;
     ALbufferlistitem *BufferListItem;
     ALuint DataPosInt, DataPosFrac;
@@ -203,6 +218,7 @@ ALvoid MixSource(ALvoice *voice, ALsource *Source, ALCdevice *Device, ALuint Sam
     }
 
     Mix = SelectMixer();
+    HrtfMix = SelectHrtfMixer();
     Resample = ((increment == FRACTIONONE && DataPosFrac == 0) ?
                 Resample_copy32_C : SelectResampler(Resampler));
 
@@ -415,8 +431,13 @@ ALvoid MixSource(ALvoice *voice, ALsource *Source, ALCdevice *Device, ALuint Sam
                     Device->FilteredData, ResampledData, DstBufferSize,
                     parms->Filters[chan].ActiveType
                 );
-                Mix(samples, parms->OutChannels, parms->OutBuffer, parms->Gains[chan],
-                    parms->Counter, OutPos, DstBufferSize);
+                if(!voice->IsHrtf)
+                    Mix(samples, parms->OutChannels, parms->OutBuffer, parms->Gains[chan],
+                        parms->Counter, OutPos, DstBufferSize);
+                else
+                    HrtfMix(parms->OutBuffer, samples, parms->Counter, voice->Offset,
+                            OutPos, parms->Hrtf.IrSize, &parms->Hrtf.Params[chan],
+                            &parms->Hrtf.State[chan], DstBufferSize);
             }
 
             /* Only the first channel for B-Format buffers (W channel) goes to