lovr.audio.get/setAbsorption;

I HOPE THIS LETS US DO UNDERWATER EFFECT

src/api/l_audio.c

@@ -199,6 +199,24 @@ static int l_lovrAudioGetCaptureStream(lua_State* L) {
   return 1;
 }
 
+static int l_lovrAudioGetAbsorption(lua_State* L) {
+  float absorption[3];
+  lovrAudioGetAbsorption(absorption);
+  lua_pushnumber(L, absorption[0]);
+  lua_pushnumber(L, absorption[1]);
+  lua_pushnumber(L, absorption[2]);
+  return 3;
+}
+
+static int l_lovrAudioSetAbsorption(lua_State* L) {
+  float absorption[3];
+  absorption[0] = luax_checkfloat(L, 1);
+  absorption[1] = luax_checkfloat(L, 2);
+  absorption[2] = luax_checkfloat(L, 3);
+  lovrAudioSetAbsorption(absorption);
+  return 0;
+}
+
 static int l_lovrAudioNewSource(lua_State* L) {
   Sound* sound = luax_totype(L, 1, Sound);
 
@@ -246,6 +264,8 @@ static const luaL_Reg lovrAudio[] = {
   { "setGeometry", l_lovrAudioSetGeometry },
   { "getSpatializer", l_lovrAudioGetSpatializer },
   { "getCaptureStream", l_lovrAudioGetCaptureStream },
+  { "getAbsorption", l_lovrAudioGetAbsorption },
+  { "setAbsorption", l_lovrAudioSetAbsorption },
   { "newSource", l_lovrAudioNewSource },
   { NULL, NULL }
 };

src/modules/audio/audio.c

@@ -58,6 +58,7 @@ static struct {
   uint32_t leftoverOffset;
   uint32_t leftoverFrames;
   float leftovers[BUFFER_SIZE * 2];
+  float absorption[3];
 } state;
 
 // Device callbacks
@@ -217,6 +218,11 @@ bool lovrAudioInit(const char* spatializer) {
   }
   lovrAssert(state.spatializer, "Must have at least one spatializer");
 
+  // SteamAudio's default frequency-dependent absorption coefficients for air
+  state.absorption[0] = .0002f;
+  state.absorption[1] = .0017f;
+  state.absorption[1] = .0182f;
+
   arr_init(&state.converters, realloc);
   return state.initialized = true;
 }
@@ -340,6 +346,16 @@ Sound* lovrAudioGetCaptureStream() {
   return state.captureStream;
 }
 
+void lovrAudioGetAbsorption(float absorption[3]) {
+  memcpy(absorption, state.absorption, 3 * sizeof(float));
+}
+
+void lovrAudioSetAbsorption(float absorption[3]) {
+  ma_mutex_lock(&state.lock);
+  memcpy(state.absorption, absorption, 3 * sizeof(float));
+  ma_mutex_unlock(&state.lock);
+}
+
 // Source
 
 Source* lovrSourceCreate(Sound* sound, bool spatial) {

src/modules/audio/audio.h

@@ -65,6 +65,8 @@ void lovrAudioSetPose(float position[4], float orientation[4]);
 bool lovrAudioSetGeometry(float* vertices, uint32_t* indices, uint32_t vertexCount, uint32_t indexCount, AudioMaterial material);
 const char* lovrAudioGetSpatializer(void);
 struct Sound* lovrAudioGetCaptureStream(void);
+void lovrAudioGetAbsorption(float absorption[3]);
+void lovrAudioSetAbsorption(float absorption[3]);
 
 // Source
 

src/modules/audio/spatializer_phonon.c

@@ -219,10 +219,13 @@ uint32_t phonon_apply(Source* source, const float* input, float* output, uint32_
     .ahead = (IPLVector3) { z[0], z[1], z[2] },
     .up = (IPLVector3) { y[0], y[1], y[2] },
     .right = (IPLVector3) { x[0], x[1], x[2] },
+    .airAbsorptionModel.type = IPL_AIRABSORPTION_EXPONENTIAL,
     .directivity.dipoleWeight = weight,
     .directivity.dipolePower = power
   };
 
+  lovrAudioGetAirAbsorption(iplSource.airAbsorptionModel.coefficients);
+
   IPLDirectOcclusionMode occlusion = IPL_DIRECTOCCLUSION_NONE;
   IPLDirectOcclusionMethod volumetric = IPL_DIRECTOCCLUSION_RAYCAST;
   float radius = 0.f;