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.

3 files changed, 22 insertions, 1 deletions

diff --git a/OpenAL32/Include/alMain.h b/OpenAL32/Include/alMain.h
index 56df4db3..1afeb1e6 100644
--- a/OpenAL32/Include/alMain.h
+++ b/OpenAL32/Include/alMain.h
@@ -617,7 +617,9 @@ typedef struct HrtfState {
 
 typedef struct HrtfParams {
     alignas(16) ALfloat Coeffs[HRIR_LENGTH][2];
+    alignas(16) ALfloat CoeffStep[HRIR_LENGTH][2];
     ALuint Delay[2];
+    ALint DelayStep[2];
 } HrtfParams;
 
 
diff --git a/OpenAL32/Include/alu.h b/OpenAL32/Include/alu.h
index 56c37fe8..0462fda8 100644
--- a/OpenAL32/Include/alu.h
+++ b/OpenAL32/Include/alu.h
@@ -71,6 +71,13 @@ typedef struct DirectParams {
         ALfilterState HighPass;
     } Filters[MAX_INPUT_CHANNELS];
 
+    struct {
+        HrtfParams Params[MAX_INPUT_CHANNELS];
+        HrtfState State[MAX_INPUT_CHANNELS];
+        ALuint IrSize;
+        ALfloat Gain;
+        ALfloat Dir[3];
+    } Hrtf;
     MixGains Gains[MAX_INPUT_CHANNELS][MAX_OUTPUT_CHANNELS];
 } DirectParams;
 
@@ -99,7 +106,8 @@ typedef void (*MixerFunc)(const ALfloat *data, ALuint OutChans,
                           ALfloat (*restrict OutBuffer)[BUFFERSIZE], struct MixGains *Gains,
                           ALuint Counter, ALuint OutPos, ALuint BufferSize);
 typedef void (*HrtfMixerFunc)(ALfloat (*restrict OutBuffer)[BUFFERSIZE], const ALfloat *data,
-                              ALuint Offset, const ALuint IrSize, const HrtfParams *hrtfparams,
+                              ALuint Counter, ALuint Offset, ALuint OutPos,
+                              const ALuint IrSize, const HrtfParams *hrtfparams,
                               HrtfState *hrtfstate, ALuint BufferSize);
 
 
diff --git a/OpenAL32/alSource.c b/OpenAL32/alSource.c
index 12bd9436..be3768f3 100644
--- a/OpenAL32/alSource.c
+++ b/OpenAL32/alSource.c
@@ -2599,6 +2599,17 @@ ALvoid SetSourceState(ALsource *Source, ALCcontext *Context, ALenum state)
 
         voice->Direct.Moving  = AL_FALSE;
         voice->Direct.Counter = 0;
+        for(i = 0;i < MAX_INPUT_CHANNELS;i++)
+        {
+            ALsizei j;
+            for(j = 0;j < HRTF_HISTORY_LENGTH;j++)
+                voice->Direct.Hrtf.State[i].History[j] = 0.0f;
+            for(j = 0;j < HRIR_LENGTH;j++)
+            {
+                voice->Direct.Hrtf.State[i].Values[j][0] = 0.0f;
+                voice->Direct.Hrtf.State[i].Values[j][1] = 0.0f;
+            }
+        }
         for(i = 0;i < (ALsizei)device->NumAuxSends;i++)
         {
             voice->Send[i].Moving  = AL_FALSE;