VERY hacky positional audio

code/core/impl/math.c

@@ -47,6 +47,11 @@ V3f V3f_Sub(V3f a, V3f b) {
 	return result;
 }
 
+F32 V2f_Dot(V2f a, V2f b) {
+	F32 result = (a.x * b.x) + (a.y * b.y);
+	return result;
+}
+
 F32 V3f_Dot(V3f a, V3f b) {
 	F32 result = (a.x * b.x) + (a.y * b.y) + (a.z * b.z);
 	return result;

code/core/math.h

@@ -118,6 +118,7 @@ function V3f V3f_Neg(V3f x);
 function V3f V3f_Scale(V3f x, F32 s);
 function V3f V3f_Sub(V3f a, V3f b);
 
+function F32 V2f_Dot(V2f a, V2f b);
 function F32 V3f_Dot(V3f a, V3f b);
 function F32 V4f_Dot(V4f a, V4f b);
 

code/first.c

@@ -25,8 +25,6 @@
 #include "game/impl/npc.c"
 #include "game/impl/bandit.c"
 
-
-
 int main(int argc, char **argv)
 {
 	(void) argc;
@@ -64,7 +62,8 @@ int main(int argc, char **argv)
 		Audio_Context *audio = M_ArenaPush(game->arena, Audio_Context);
 		Audio_Init(game->arena, audio, 0.15f);
 
-		Audio_Play(audio, 1);
+		U32 bgm = Audio_Play(audio, 0);
+		U32 saloon_music = Audio_Play(audio, 1);
 
 		SDL_ResumeAudioStreamDevice(audio->stream);
 
@@ -84,6 +83,11 @@ int main(int argc, char **argv)
 		World *world = M_ArenaPush(arena, World);
     LoadWorld(arena, world);
     game->world = world;
+
+		world->audio = audio;
+		world->audio_handles[0] = bgm;
+		world->audio_handles[1] = saloon_music;
+
     world->arena = arena;
     world->random = Random_Seed(29237489723847);
     world->npcCount = 127;
@@ -333,7 +337,7 @@ int main(int argc, char **argv)
 		}
 
     if(!game->editor.enabled) {
-		  UpdateWorld(1.0f / 60.0f, game->world);
+		  UpdateWorld(1.0f / 250.0f, game->world);
 
       game->camera.p.x = game->world->player.collision.pos.x;
       game->camera.p.y = game->world->player.collision.pos.y;

code/game/impl/player.c

@@ -164,6 +164,16 @@ void PlayerUpdate(F32 delta, Player *player) {
   dir = V2f_Scale(NormaliseV2F(dir), PLAYER_SPEED*delta);
   player->collision.pos.x += dir.x;
   player->collision.pos.y += dir.y;
+
+	V2f test;
+	test.x = player->collision.pos.x - 14;
+	test.y = player->collision.pos.y - 14;
+
+	F32 len = V2f_Dot(test, test);
+	F32 vol = Max(0.0f, 1.0f - (len / 25.0f));
+
+	Audio_ChangeVolume(player->world->audio, player->world->audio_handles[1], vol);
+	Audio_ChangeVolume(player->world->audio, player->world->audio_handles[0], 1.0f - vol);
 }
 
 void PlayerDraw(D_Context *draw, Player *player) {

code/game/world.h

@@ -59,6 +59,9 @@ struct World {
   U32 propCount;
   U32 hitboxCount;
 
+	Audio_Context *audio;
+	U32 audio_handles[2];
+
   //// Player
   Player player;
 

code/os/audio.h

@@ -13,6 +13,8 @@ struct Audio_Track {
 
 	Audio_Data *data;
 
+	F32 volume;
+
 	U32 n_played;
 	U32 next; // to play if playing, free otherwise
 };
@@ -34,6 +36,8 @@ struct Audio_Context {
 };
 
 function void Audio_Init(M_Arena *arena, Audio_Context *audio, F32 volume);
-function void Audio_Play(Audio_Context *audio, U32 index);
+function U32  Audio_Play(Audio_Context *audio, U32 index);
+
+function void Audio_ChangeVolume(Audio_Context *audio, U32 handle, F32 volume);
 
 #endif  // LD_OS_AUDIO_H_

code/os/core.c

@@ -48,8 +48,8 @@ internal void SDL_SubmitAudio(void *user, SDL_AudioStream *stream, int needed, i
 			U32 off    = track->n_played << 1; // played n frames, thus double to n samples
 
 			for (U32 f = 0; f < play; ++f) {
-				*l0++ += cast(F32) (track->data->samples[off + (2 * f) + 0]) * audio->volume;
+				*l0++ += cast(F32) (track->data->samples[off + (2 * f) + 0]) * track->volume * audio->volume;
-				*r0++ += cast(F32) (track->data->samples[off + (2 * f) + 1]) * audio->volume;
+				*r0++ += cast(F32) (track->data->samples[off + (2 * f) + 1]) * track->volume * audio->volume;
 			}
 
 			track->n_played += play;
@@ -136,7 +136,6 @@ void Audio_Init(M_Arena *arena, Audio_Context *audio, F32 volume) {
 			}
 
 			audio->n_tracks = 16;
-			//audio->tracks   = M_ArenaPush(arena, Audio_Track, audio->n_tracks);
 
 			for (U32 it = 1; it < audio->n_tracks; ++it) {
 				audio->tracks[it].next = it + 1;
@@ -153,19 +152,30 @@ void Audio_Init(M_Arena *arena, Audio_Context *audio, F32 volume) {
 	}
 }
 
-void Audio_Play(Audio_Context *audio, U32 index) {
+U32 Audio_Play(Audio_Context *audio, U32 index) {
+	U32 result = 0;
 	if (audio->free != 0 && SDL_LockAudioStream(audio->stream)) {
-		U32 idx = audio->free;
+		result = audio->free;
 
-		Audio_Track *track = &audio->tracks[idx];
+		Audio_Track *track = &audio->tracks[result];
 		audio->free = track->next;
 
 		track->playing  = true;
 		track->data     = &audio->sounds[index];
 		track->n_played = 0;
+		track->volume   = 1.0f;
 		track->next     = audio->head;
-		audio->head     = idx;
+		audio->head     = result;
 
 		SDL_UnlockAudioStream(audio->stream);
 	}
+
+	return result;
+}
+
+void Audio_ChangeVolume(Audio_Context *audio, U32 handle, F32 volume) {
+	if (SDL_LockAudioStream(audio->stream)) {
+		audio->tracks[handle].volume = volume;
+		SDL_UnlockAudioStream(audio->stream);
+	}
 }