Implemented load audio and music files as well the basic audio playback

functionality.

src/AssetManager.c

@@ -171,7 +171,16 @@ AssetID load_asset_to_manager(AssetManager *am, const char *path,
 
   AssetID existing_id =
       get_asset_id_from_id_node(am, &(am->hashed_path_ids[hash_index]), path);
+
   if (existing_id != INVALID_ID) {
+    if (am->assets[existing_id].type != type) {
+      // If the user tries to load an asset that is already loaded, but they
+      // try to load it as a type that doesn't match the asset's actual type,
+      // we return an INVALID_ID to ensure that the user doesn't try using the
+      // asset with functions that work on the wrong type
+      return INVALID_ID;
+    }
+
     ++(am->user_counter[existing_id]);
     return existing_id;
   }
@@ -189,16 +198,25 @@ AssetID load_asset_to_manager(AssetManager *am, const char *path,
     asset.data.texture = load_texture(renderer, path);
 
     if (!(asset.data.texture)) {
-      printf("Error loading %s: %s\n", path, SDL_GetError());
       loaded = false;
     }
 
     break;
   case ASSET_TYPE_AUDIO_FX:
-    // TODO (Abdelrahman): Implement loading audio chunks
+    asset.data.chunk = Mix_LoadWAV(path);
+
+    if (!(asset.data.chunk)) {
+      loaded = false;
+    }
+
     break;
   case ASSET_TYPE_MUSIC:
-    // TODO (Abdelrahman): Implement loading music
+    asset.data.music = Mix_LoadMUS(path);
+
+    if (!(asset.data.music)) {
+      loaded = false;
+    }
+
     break;
   default:
     loaded = false;
@@ -206,6 +224,7 @@ AssetID load_asset_to_manager(AssetManager *am, const char *path,
   }
 
   if (!loaded) {
+    printf("Error loading %s: %s\n", path, SDL_GetError());
     return INVALID_ID;
   }
 
@@ -266,7 +285,7 @@ void remove_asset_from_manager(AssetManager *am, AssetID *id_ptr) {
   remove_id_node(&(am->hashed_path_ids[hash_index]), id);
 
   free(am->assets[id].path);
-  am->assets[id].path = 0;
+  am->assets[id].path = NULL;
 
   switch (am->assets[id].type) {
   case ASSET_TYPE_IMAGE:
@@ -274,10 +293,12 @@ void remove_asset_from_manager(AssetManager *am, AssetID *id_ptr) {
     am->assets[id].data.texture = NULL;
     break;
   case ASSET_TYPE_AUDIO_FX:
-    // TODO (Abdelrahman): Implement closing audio chunk
+    Mix_FreeChunk(am->assets[id].data.chunk);
+    am->assets[id].data.chunk = NULL;
     break;
   case ASSET_TYPE_MUSIC:
-    // TODO (Abdelrahman): Implement closing music
+    Mix_FreeMusic(am->assets[id].data.music);
+    am->assets[id].data.music = NULL;
     break;
   default:
     break;
@@ -289,7 +310,7 @@ void remove_asset_from_manager(AssetManager *am, AssetID *id_ptr) {
 }
 
 SDL_Texture *get_texture(AssetManager *am, AssetID id) {
-  if (am->assets[id].type != ASSET_TYPE_IMAGE) {
+  if (id < 0 || am->assets[id].type != ASSET_TYPE_IMAGE) {
     return NULL;
   }
 
@@ -297,7 +318,7 @@ SDL_Texture *get_texture(AssetManager *am, AssetID id) {
 }
 
 Mix_Chunk *get_audio_chunk(AssetManager *am, AssetID id) {
-  if (am->assets[id].type != ASSET_TYPE_AUDIO_FX) {
+  if (id < 0 || am->assets[id].type != ASSET_TYPE_AUDIO_FX) {
     return NULL;
   }
 
@@ -305,46 +326,48 @@ Mix_Chunk *get_audio_chunk(AssetManager *am, AssetID id) {
 }
 
 Mix_Music *get_music(AssetManager *am, AssetID id) {
-  if (am->assets[id].type != ASSET_TYPE_MUSIC) {
+  if (id < 0 || am->assets[id].type != ASSET_TYPE_MUSIC) {
     return NULL;
   }
 
   return am->assets[id].data.music;
 }
 
-void destroy_asset_manager(AssetManager *am) {
-  if (!am) {
+void destroy_asset_manager(AssetManager **am) {
+  if (!(*am)) {
     return;
   }
 
-  for (size_t i = 0; i < am->count; ++i) {
-    am->user_counter[i] = 0;
+  for (size_t i = 0; i < (*am)->count; ++i) {
+    (*am)->user_counter[i] = 0;
 
-    size_t hash_index = hash_path(am->assets[i].path);
-    remove_id_node(&(am->hashed_path_ids[hash_index]), i);
+    size_t hash_index = hash_path((*am)->assets[i].path);
+    remove_id_node(&((*am)->hashed_path_ids[hash_index]), i);
 
-    free(am->assets[i].path);
-    am->assets[i].path = NULL;
+    free((*am)->assets[i].path);
+    (*am)->assets[i].path = NULL;
 
-    switch (am->assets[i].type) {
+    switch ((*am)->assets[i].type) {
     case ASSET_TYPE_IMAGE:
-      SDL_DestroyTexture(am->assets[i].data.texture);
-      am->assets[i].data.texture = NULL;
+      SDL_DestroyTexture((*am)->assets[i].data.texture);
+      (*am)->assets[i].data.texture = NULL;
       break;
     case ASSET_TYPE_AUDIO_FX:
-      // TODO (Abdelrahman): Implement closing audio chunk
+      Mix_FreeChunk((*am)->assets[i].data.chunk);
+      (*am)->assets[i].data.chunk = NULL;
       break;
     case ASSET_TYPE_MUSIC:
-      // TODO (Abdelrahman): Implement closing music
+      Mix_FreeMusic((*am)->assets[i].data.music);
+      (*am)->assets[i].data.music = NULL;
       break;
     default:
       break;
     }
   }
 
-  am->count = 0;
-  am->deleted_count = 0;
+  (*am)->count = 0;
+  (*am)->deleted_count = 0;
 
-  free(am);
-  am = NULL;
+  free(*am);
+  *am = NULL;
 }

src/GameEngine.c

@@ -6,6 +6,7 @@
 #include "SDL_error.h"
 #include "SDL_events.h"
 #include "SDL_image.h"
+#include "SDL_mixer.h"
 #include "SDL_pixels.h"
 #include "SDL_render.h"
 #include "SDL_timer.h"
@@ -13,8 +14,8 @@
 #include "constants.h"
 #include "engine_build_config.h"
 #include "reusable_ids.h"
-#include <SDL2/SDL_mixer.h>
 #include <stdbool.h>
+#include <stddef.h>
 #include <stdint.h>
 #include <stdlib.h>
 
@@ -32,8 +33,9 @@ INTERNAL struct game_engine {
   AssetManager *asset_manager;
 } GameEngine;
 
-bool init_game(const char *game_name, int window_width, int window_height,
-               SDL_Color window_background_color, bool full_screen) {
+bool init_game(const char *game_name, uint32_t window_width,
+               uint32_t window_height, SDL_Color window_background_color,
+               bool full_screen, uint8_t audio_tracks) {
   bool initialisation_complete = true;
 
   if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
@@ -47,11 +49,36 @@ bool init_game(const char *game_name, int window_width, int window_height,
   uint32_t img_flags = IMG_INIT_PNG | IMG_INIT_TIF;
   if ((IMG_Init(img_flags) & img_flags) != img_flags) {
 #ifdef DEBUG_ENGINE
-    printf("Failed to initialise SDL. Error: %s\n", IMG_GetError());
+    printf("Failed to initialise SDL_image. Error: %s\n", IMG_GetError());
 #endif /* DEBUG_ENGINE */
     initialisation_complete = false;
   }
 
+  // We're only interested in initialising SDL_mixer with WAVE files, so no
+  // need to pass any flags
+  if (Mix_Init(0) != 0) {
+#ifdef DEBUG_ENGINE
+    printf("Failed to initialise SDL_mixer. Error: %s\n", Mix_GetError());
+#endif /* DEBUG_ENGINE */
+    initialisation_complete = false;
+  }
+
+  if (Mix_OpenAudio(48000, MIX_DEFAULT_FORMAT, 2, 2048) < 0) {
+#ifdef DEBUG_ENGINE
+    printf("Failed to open audio device. Error: %s\n", Mix_GetError());
+#endif /* DEBUG_ENGINE */
+    initialisation_complete = false;
+  }
+
+  if (audio_tracks > 0) {
+    if (Mix_AllocateChannels(audio_tracks) != audio_tracks) {
+#ifdef DEBUG_ENGINE
+      printf("Failed to allocate the required tracks.\n");
+#endif /* DEBUG_ENGINE */
+      initialisation_complete = false;
+    }
+  }
+
   if (!init_window(&(GameEngine.window), game_name, window_width, window_height,
                    window_background_color, full_screen)) {
 #ifdef DEBUG_ENGINE
@@ -62,13 +89,11 @@ bool init_game(const char *game_name, int window_width, int window_height,
   }
 
   GameEngine.object_store = create_object_store();
-
   if (!(GameEngine.object_store)) {
     initialisation_complete = false;
   }
 
   GameEngine.asset_manager = create_asset_manager();
-
   if (!(GameEngine.asset_manager)) {
     initialisation_complete = false;
   }
@@ -125,10 +150,333 @@ void render_texture_asset(AssetID id, float x, float y, float w, float h) {
 
   SDL_Texture *texture = get_texture(GameEngine.asset_manager, id);
 
+  if (!texture) {
+    return;
+  }
+
   render_texture(GameEngine.window.renderer, texture, x, y, w, h);
 }
 
+int8_t play_audio_asset(AssetID id, int16_t loops, bool fade_in,
+                        uint32_t fade_length_in_ms) {
+  if (id < 0) {
+    return -1;
+  }
+
+  Mix_Chunk *chunk = get_audio_chunk(GameEngine.asset_manager, id);
+  if (!chunk) {
+    return -1;
+  }
+
+  if (fade_in) {
+    return Mix_FadeInChannel(-1, chunk, loops, fade_length_in_ms);
+  } else {
+    return Mix_PlayChannel(-1, chunk, loops);
+  }
+}
+
+void pause_audio_asset_on_track(AssetID id, uint8_t track) {
+  if (id < 0) {
+    return;
+  }
+
+  Mix_Chunk *chunk = get_audio_chunk(GameEngine.asset_manager, id);
+  if (!chunk || chunk != Mix_GetChunk(track)) {
+    return;
+  }
+
+  Mix_Pause(track);
+}
+
+void resume_audio_asset_on_track(AssetID id, uint8_t track) {
+  if (id < 0) {
+    return;
+  }
+
+  Mix_Chunk *chunk = get_audio_chunk(GameEngine.asset_manager, id);
+  if (!chunk || chunk != Mix_GetChunk(track)) {
+    return;
+  }
+
+  Mix_Resume(track);
+}
+
+void stop_audio_asset_on_track(AssetID id, uint8_t track) {
+  if (id < 0) {
+    return;
+  }
+
+  Mix_Chunk *chunk = get_audio_chunk(GameEngine.asset_manager, id);
+  if (!chunk || chunk != Mix_GetChunk(track)) {
+    return;
+  }
+
+  Mix_HaltChannel(track);
+}
+
+void fade_out_audio_asset_on_track(AssetID id, uint8_t track,
+                                   uint32_t fade_length_in_ms) {
+  if (id < 0) {
+    return;
+  }
+
+  Mix_Chunk *chunk = get_audio_chunk(GameEngine.asset_manager, id);
+  if (!chunk || chunk != Mix_GetChunk(track)) {
+    return;
+  }
+
+  Mix_FadeOutChannel(track, fade_length_in_ms);
+}
+
+void pause_all_instances_of_audio_asset(AssetID id) {
+  if (id < 0) {
+    return;
+  }
+
+  Mix_Chunk *chunk = get_audio_chunk(GameEngine.asset_manager, id);
+  if (!chunk) {
+    return;
+  }
+
+  size_t channel_count = Mix_AllocateChannels(-1);
+
+  for (size_t i = 0; i < channel_count; ++i) {
+    if (chunk == Mix_GetChunk(i)) {
+      Mix_Pause(i);
+    }
+  }
+}
+
+void resume_all_instances_of_audio_asset(AssetID id) {
+  if (id < 0) {
+    return;
+  }
+
+  Mix_Chunk *chunk = get_audio_chunk(GameEngine.asset_manager, id);
+  if (!chunk) {
+    return;
+  }
+
+  size_t channel_count = Mix_AllocateChannels(-1);
+
+  for (size_t i = 0; i < channel_count; ++i) {
+    if (chunk == Mix_GetChunk(i)) {
+      Mix_Resume(i);
+    }
+  }
+}
+
+void stop_all_instances_of_audio_asset(AssetID id) {
+  if (id < 0) {
+    return;
+  }
+
+  Mix_Chunk *chunk = get_audio_chunk(GameEngine.asset_manager, id);
+  if (!chunk) {
+    return;
+  }
+
+  size_t channel_count = Mix_AllocateChannels(-1);
+
+  for (size_t i = 0; i < channel_count; ++i) {
+    if (chunk == Mix_GetChunk(i)) {
+      Mix_HaltChannel(i);
+    }
+  }
+}
+
+void fade_out_all_instances_of_audio_asset(AssetID id,
+                                           uint32_t fade_length_in_ms) {
+  if (id < 0) {
+    return;
+  }
+
+  Mix_Chunk *chunk = get_audio_chunk(GameEngine.asset_manager, id);
+  if (!chunk) {
+    return;
+  }
+
+  size_t channel_count = Mix_AllocateChannels(-1);
+
+  for (size_t i = 0; i < channel_count; ++i) {
+    if (chunk == Mix_GetChunk(i)) {
+      Mix_FadeOutChannel(i, fade_length_in_ms);
+    }
+  }
+}
+
+int8_t get_audio_asset_volume(AssetID id) {
+  if (id < 0) {
+    return -1;
+  }
+
+  Mix_Chunk *chunk = get_audio_chunk(GameEngine.asset_manager, id);
+  if (!chunk) {
+    return -1;
+  }
+
+  return chunk->volume;
+}
+
+void set_audio_asset_volume(AssetID id, int8_t volume) {
+  if (id < 0) {
+    return;
+  }
+
+  Mix_Chunk *chunk = get_audio_chunk(GameEngine.asset_manager, id);
+  if (!chunk) {
+    return;
+  }
+
+  Mix_VolumeChunk(chunk, volume);
+}
+
+void play_music_asset(AssetID id, int16_t loops, bool fade_in,
+                      uint32_t fade_length_in_ms) {
+  if (id < 0 || is_music_asset_playing(id)) {
+    return;
+  }
+
+  Mix_Music *music = get_music(GameEngine.asset_manager, id);
+  if (!music) {
+    return;
+  }
+
+  if (fade_in) {
+    Mix_FadeInMusic(music, loops, fade_length_in_ms);
+  } else {
+    Mix_PlayMusic(music, loops);
+  }
+}
+
+void pause_music_asset(AssetID id) {
+  if (id < 0 || !is_music_asset_playing(id)) {
+    return;
+  }
+
+  Mix_Music *music = get_music(GameEngine.asset_manager, id);
+  if (!music) {
+    return;
+  }
+
+  Mix_PauseMusic();
+}
+
+void resume_music_asset(AssetID id) {
+  if (id < 0 || !is_music_asset_playing(id)) {
+    return;
+  }
+
+  Mix_Music *music = get_music(GameEngine.asset_manager, id);
+  if (!music) {
+    return;
+  }
+
+  Mix_ResumeMusic();
+}
+
+void stop_music_asset(AssetID id) {
+  if (id < 0 || !is_music_asset_playing(id)) {
+    return;
+  }
+
+  Mix_Music *music = get_music(GameEngine.asset_manager, id);
+  if (!music) {
+    return;
+  }
+
+  Mix_HaltMusic();
+}
+
+void fade_out_music_asset(AssetID id, uint32_t fade_length_in_ms) {
+  if (id < 0 || !is_music_asset_playing(id)) {
+    return;
+  }
+
+  Mix_Music *music = get_music(GameEngine.asset_manager, id);
+  if (!music) {
+    return;
+  }
+
+  Mix_FadeOutMusic(fade_length_in_ms);
+}
+
+int8_t get_music_asset_volume(AssetID id) {
+  if (id < 0) {
+    return -1;
+  }
+
+  Mix_Music *music = get_music(GameEngine.asset_manager, id);
+  if (!music) {
+    return -1;
+  }
+
+  return Mix_GetMusicVolume(music);
+}
+
+void set_music_asset_volume(AssetID id, int8_t volume) {
+  if (id < 0 || !is_music_asset_playing(id)) {
+    return;
+  }
+
+  Mix_Music *music = get_music(GameEngine.asset_manager, id);
+  if (!music) {
+    return;
+  }
+
+  Mix_VolumeMusic(volume);
+}
+
+bool is_music_object_playing(Mix_Music *music) {
+  if (!Mix_PlayingMusic()) {
+    return false;
+  }
+
+  // The Mix_GetMusic* functions used here all return the result for the
+  // currently playing music when passed a NULL pointer. We use that to compare
+  // the data of the Mix_Music object passed to the function to the data of the
+  // currently playing music.
+  //
+  // TODO (Abdelrahman): This is a bit of a hack. Figure out if there is
+  // a better alternative to check if a Mix_Music object is currently playing.
+  return Mix_GetMusicType(music) == Mix_GetMusicType(NULL) &&
+         Mix_GetMusicTitle(music) == Mix_GetMusicTitle(NULL) &&
+         Mix_GetMusicArtistTag(music) == Mix_GetMusicArtistTag(NULL) &&
+         Mix_GetMusicAlbumTag(music) == Mix_GetMusicAlbumTag(NULL);
+}
+
+bool is_music_asset_playing(AssetID id) {
+  if (id < 0) {
+    return false;
+  }
+
+  Mix_Music *music = get_music(GameEngine.asset_manager, id);
+  if (!music) {
+    return false;
+  }
+
+  return is_music_object_playing(music);
+}
+
+void pause_playing_music() { Mix_PauseMusic(); }
+
+void resume_playing_music() { Mix_ResumeMusic(); }
+
+void stop_playing_music() { Mix_HaltMusic(); }
+
+void fade_out_playing_music(uint32_t fade_length_in_ms) {
+  Mix_FadeOutMusic(fade_length_in_ms);
+}
+
+void set_playing_music_volume(int8_t volume) { Mix_VolumeMusic(volume); }
+
+bool is_music_playing() { return Mix_PlayingMusic(); }
+
 void close_asset(AssetID *id) {
+  if (*id < 0) {
+    return;
+  }
+
   remove_asset_from_manager(GameEngine.asset_manager, id);
 }
 
@@ -183,11 +531,9 @@ void render() {
 }
 
 void close_game() {
-  destroy_asset_manager(GameEngine.asset_manager);
-  GameEngine.asset_manager = NULL;
+  destroy_asset_manager(&(GameEngine.asset_manager));
 
-  destroy_object_store(GameEngine.object_store);
-  GameEngine.object_store = NULL;
+  destroy_object_store(&(GameEngine.object_store));
 
   destroy_window(&(GameEngine.window));
 
@@ -197,6 +543,10 @@ void close_game() {
 
   GameEngine.running = false;
 
+  Mix_CloseAudio();
+
+  Mix_Quit();
+
   IMG_Quit();
 
   SDL_Quit();

src/ObjectStore.c

@@ -136,23 +136,23 @@ void render_all_objects(ObjectStore *os) {
   }
 }
 
-void destroy_object_store(ObjectStore *os) {
-  if (!os) {
+void destroy_object_store(ObjectStore **os) {
+  if (!(*os)) {
     return;
   }
 
-  for (size_t i = 0; i < os->count; ++i) {
-    os->object_ptrs[i] = NULL;
-    os->event_handlers[i] = NULL;
-    os->update_funcs[i] = NULL;
-    os->render_funcs[i] = NULL;
+  for (size_t i = 0; i < (*os)->count; ++i) {
+    (*os)->object_ptrs[i] = NULL;
+    (*os)->event_handlers[i] = NULL;
+    (*os)->update_funcs[i] = NULL;
+    (*os)->render_funcs[i] = NULL;
   }
 
-  os->count = 0;
-  os->deleted_count = 0;
+  (*os)->count = 0;
+  (*os)->deleted_count = 0;
 
-  free(os);
-  os = NULL;
+  free(*os);
+  *os = NULL;
 }
 
 #ifdef DEBUG_ENGINE

src/Renderer.c

@@ -68,15 +68,15 @@ SDL_Texture *load_texture(const Renderer *renderer, const char *path) {
   return IMG_LoadTexture(renderer->SDL_base_renderer, path);
 }
 
-void destroy_renderer(Renderer *renderer) {
-  if (renderer) {
-    if (renderer->SDL_base_renderer) {
-      SDL_DestroyRenderer(renderer->SDL_base_renderer);
-      renderer->SDL_base_renderer = NULL;
+void destroy_renderer(Renderer **renderer) {
+  if (*renderer) {
+    if ((*renderer)->SDL_base_renderer) {
+      SDL_DestroyRenderer((*renderer)->SDL_base_renderer);
+      (*renderer)->SDL_base_renderer = NULL;
     }
 
-    free(renderer);
-    renderer = NULL;
+    free(*renderer);
+    *renderer = NULL;
 
 #ifdef DEBUG_ENGINE
     printf("Renderer destroyed successfully\n");

src/Window.c

@@ -71,8 +71,7 @@ void destroy_window(Window *wnd) {
 
   if (wnd->SDL_base_window) {
     if (wnd->renderer) {
-      destroy_renderer(wnd->renderer);
-      wnd->renderer = NULL;
+      destroy_renderer(&(wnd->renderer));
     }
 
     SDL_DestroyWindow(wnd->SDL_base_window);