Mix to multichannel for effects

This mixes to a 4-channel first-order ambisonics buffer. With ACN ordering and
N3D scaling, this makes it easy to remain compatible with effects that only
care about mono input since channel 0 is an unattenuated mono signal.

1 files changed, 20 insertions, 2 deletions

diff --git a/Alc/panning.c b/Alc/panning.c
index dccb495e..c4eb3f82 100644
--- a/Alc/panning.c
+++ b/Alc/panning.c
@@ -27,8 +27,7 @@
 #include <assert.h>
 
 #include "alMain.h"
-#include "AL/al.h"
-#include "AL/alc.h"
+#include "alAuxEffectSlot.h"
 #include "alu.h"
 #include "bool.h"
 
@@ -569,3 +568,22 @@ ALvoid aluInitPanning(ALCdevice *device)
                   &device->NumChannels, AL_TRUE);
     device->AmbiScale = ambiscale;
 }
+
+void aluInitEffectPanning(ALeffectslot *slot)
+{
+    static const ChannelMap FirstOrderN3D[4] = {
+        { BFormatW, { 1.0f, 0.0f, 0.0f, 0.0f } },
+        { BFormatY, { 0.0f, 1.0f, 0.0f, 0.0f } },
+        { BFormatZ, { 0.0f, 0.0f, 1.0f, 0.0f } },
+        { BFormatX, { 0.0f, 0.0f, 0.0f, 1.0f } },
+    };
+    static const enum Channel AmbiChannels[MAX_OUTPUT_CHANNELS] = {
+        BFormatW, BFormatY, BFormatZ, BFormatX, InvalidChannel
+    };
+
+    memset(slot->AmbiCoeffs, 0, sizeof(slot->AmbiCoeffs));
+    slot->NumChannels = 0;
+
+    SetChannelMap(AmbiChannels, slot->AmbiCoeffs, FirstOrderN3D, COUNTOF(FirstOrderN3D),
+                  &slot->NumChannels, AL_FALSE);
+}