From 0e04346b8c7aedf55b3acfb7dd9301abbc3358c5 Mon Sep 17 00:00:00 2001
From: cosmonaut <evan@moonside.games>
Date: Tue, 9 Nov 2021 15:32:22 -0800
Subject: [PATCH] fix effect chains making sounds mono

---
 src/FAudioGMS.c | 119 +++++++++++++++++++++++++-----------------------
 1 file changed, 63 insertions(+), 56 deletions(-)

diff --git a/src/FAudioGMS.c b/src/FAudioGMS.c
index d8de43f..09a7b7c 100644
--- a/src/FAudioGMS.c
+++ b/src/FAudioGMS.c
@@ -506,6 +506,57 @@ void FAudioGMS_Init(double spatialDistanceScale, double timestep)
     fflush(stdout);
 }
 
+double FAudioGMS_StaticSound_LoadWAV(char *filePath)
+{
+    RETURN_ON_NULL_DEVICE(-1.0)
+    drwav_uint64 frameCount;
+
+    FAudioGMS_StaticSound *sound = SDL_malloc(sizeof(FAudioGMS_StaticSound));
+    float *pSampleData = drwav_open_file_and_read_pcm_frames_f32(
+        filePath,
+        &sound->channels,
+        &sound->samplesPerSecond,
+        &frameCount,
+        NULL);
+    if (pSampleData == NULL)
+    {
+        Log("Error opening WAV file: ");
+        Log(filePath);
+        SDL_free(sound);
+        return -1;
+    }
+
+    sound->buffer.AudioBytes = (uint32_t)(frameCount * sound->channels * sizeof(float));
+    sound->buffer.Flags = 0;
+    sound->buffer.LoopBegin = 0;
+    sound->buffer.LoopCount = 0;
+    sound->buffer.LoopLength = 0;
+    sound->buffer.PlayBegin = 0;
+    sound->buffer.PlayLength = frameCount;
+    sound->buffer.pAudioData = (uint8_t *)pSampleData;
+    sound->buffer.pContext = NULL;
+
+    sound->lengthInSeconds = frameCount / sound->samplesPerSecond;
+
+    if (device->staticSoundIndexStack.count > 0)
+    {
+        sound->id = IdStack_Pop(&device->staticSoundIndexStack);
+    }
+    else
+    {
+        sound->id = device->staticSoundCount;
+
+        device->staticSounds = SDL_realloc(
+            device->staticSounds,
+            (device->staticSoundCount + 1) * sizeof(FAudioGMS_StaticSound *));
+        device->staticSoundCount += 1;
+    }
+
+    device->staticSounds[sound->id] = sound;
+
+    return (double)sound->id;
+}
+
 /* Taken from
  * https://github.com/FNA-XNA/FNA/blob/master/src/Audio/SoundEffectInstance.cs
  */
@@ -563,61 +614,8 @@ static void SetPanMatrixCoefficients(FAudioGMS_SoundInstance *instance)
     }
 }
 
-double FAudioGMS_StaticSound_LoadWAV(char *filePath)
+static void FAudioGMS_INTERNAl_SoundInstance_ApplyPan(FAudioGMS_SoundInstance* instance) 
 {
-    RETURN_ON_NULL_DEVICE(-1.0)
-    drwav_uint64 frameCount;
-
-    FAudioGMS_StaticSound *sound = SDL_malloc(sizeof(FAudioGMS_StaticSound));
-    float *pSampleData = drwav_open_file_and_read_pcm_frames_f32(
-        filePath,
-        &sound->channels,
-        &sound->samplesPerSecond,
-        &frameCount,
-        NULL);
-    if (pSampleData == NULL)
-    {
-        Log("Error opening WAV file: ");
-        Log(filePath);
-        SDL_free(sound);
-        return -1;
-    }
-
-    sound->buffer.AudioBytes = (uint32_t)(frameCount * sound->channels * sizeof(float));
-    sound->buffer.Flags = 0;
-    sound->buffer.LoopBegin = 0;
-    sound->buffer.LoopCount = 0;
-    sound->buffer.LoopLength = 0;
-    sound->buffer.PlayBegin = 0;
-    sound->buffer.PlayLength = frameCount;
-    sound->buffer.pAudioData = (uint8_t *)pSampleData;
-    sound->buffer.pContext = NULL;
-
-    sound->lengthInSeconds = frameCount / sound->samplesPerSecond;
-
-    if (device->staticSoundIndexStack.count > 0)
-    {
-        sound->id = IdStack_Pop(&device->staticSoundIndexStack);
-    }
-    else
-    {
-        sound->id = device->staticSoundCount;
-
-        device->staticSounds = SDL_realloc(
-            device->staticSounds,
-            (device->staticSoundCount + 1) * sizeof(FAudioGMS_StaticSound *));
-        device->staticSoundCount += 1;
-    }
-
-    device->staticSounds[sound->id] = sound;
-
-    return (double)sound->id;
-}
-
-static void FAudioGMS_INTERNAL_SoundInstance_SetPan(FAudioGMS_SoundInstance *instance, float pan)
-{
-    pan = SDL_max(-1.0, SDL_min(1.0, pan));
-    instance->pan = pan;
     SetPanMatrixCoefficients(instance);
 
     FAudioVoice_SetOutputMatrix(
@@ -629,6 +627,13 @@ static void FAudioGMS_INTERNAL_SoundInstance_SetPan(FAudioGMS_SoundInstance *ins
         0);
 }
 
+static void FAudioGMS_INTERNAL_SoundInstance_SetPan(FAudioGMS_SoundInstance *instance, float pan)
+{
+    pan = SDL_max(-1.0, SDL_min(1.0, pan));
+    instance->pan = pan;
+    FAudioGMS_INTERNAl_SoundInstance_ApplyPan(instance);
+}
+
 static void FAudioGMS_INTERNAL_SoundInstance_UpdatePitch(FAudioGMS_SoundInstance *instance)
 {
     float doppler = 1.0f;
@@ -1750,7 +1755,7 @@ static void FAudioGMS_INTERNAL_Voice_SetEffectGain(FAudioGMS_Voice *voice, float
         float *outputMatrix = SDL_stack_alloc(float, voice->effectSends.SendCount);
 
         outputMatrix[0] = effectGain;
-        if (voice->effectSends.SendCount == 2)
+        if (voice->handle->outputChannels == 2)
         {
             outputMatrix[1] = effectGain;
         }
@@ -1758,7 +1763,7 @@ static void FAudioGMS_INTERNAL_Voice_SetEffectGain(FAudioGMS_Voice *voice, float
         FAudioVoice_SetOutputMatrix(
             voice->handle,
             voice->effectVoice,
-            voice->effectSends.SendCount,
+            voice->handle->outputChannels,
             1,
             outputMatrix,
             0);
@@ -1926,6 +1931,8 @@ void FAudioGMS_SoundInstance_SetEffectChain(
     if (instance != NULL && effectChain != NULL)
     {
         FAudioGMS_INTERNAL_SetEffectChain(&instance->voice, effectChain, effectGain);
+        /* re-apply pan after setting chain because sends may have changed */
+        FAudioGMS_INTERNAl_SoundInstance_ApplyPan(instance);
     }
 }