punchie-engine/src/GameEngine.c

#include "GameEngine.h"
#include "AssetManager.h"
#include "ObjectStore.h"
#include "Renderer.h"
#include "SDL.h"
#include "SDL_error.h"
#include "SDL_events.h"
#include "SDL_hints.h"
#include "SDL_image.h"
#include "SDL_mixer.h"
#include "SDL_pixels.h"
#include "SDL_platform.h"
#include "SDL_rect.h"
#include "SDL_render.h"
#include "SDL_surface.h"
#include "SDL_timer.h"
#include "SDL_ttf.h"
#include "SDL_video.h"
#include "Window.h"
#include "aliases.h"
#include "constants.h"
#include "engine_build_config.h"
#include "reusable_ids.h"
#include <stdbool.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>

#ifdef DEBUG_ENGINE
#include <stdio.h>
#endif /* DEBUG_ENGINE */

INTERNAL struct game_engine {
  bool running;
  f32 delta;
  u64 last_time;
  Window window;
  SDL_Event event;
  ObjectStore *object_store;
  AssetManager *asset_manager;
} GameEngine;

bool init_engine(const char *game_name, WindowSize window_size,
                 SDL_Color window_background_color, bool full_screen,
                 u8 audio_tracks) {
  bool initialisation_complete = true;
  const char *current_platform = SDL_GetPlatform();

  if (strcmp(current_platform, "Linux") == 0) {
    SDL_SetHint(SDL_HINT_VIDEODRIVER, "wayland,x11");
  }

  if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
#ifdef DEBUG_ENGINE
    printf("Failed to initialise SDL. Error: %s\n", SDL_GetError());
#endif /* DEBUG_ENGINE */

    return false;
  }

  u32 img_flags = IMG_INIT_PNG;
  if (strcmp(current_platform, "Android") != 0) {
    // Apparently, Android devices don't support TIFF images, so we only enable
    // TIFF support when we are not running Android.
    //
    // TODO (Abdelrahman): Check if iOS devices support TIFF images.
    img_flags |= IMG_INIT_TIF;
  }

  if ((IMG_Init(img_flags) & img_flags) != img_flags) {
#ifdef DEBUG_ENGINE
    printf("Failed to initialise SDL_image. Error: %s\n", IMG_GetError());
#endif /* DEBUG_ENGINE */
    initialisation_complete = false;
  }

  if (TTF_Init() < 0) {
#ifdef DEBUG_ENGINE
    printf("Failed to initialise SDL_ttf. Error: %s\n", TTF_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_size,
                   window_background_color, full_screen)) {
#ifdef DEBUG_ENGINE
    printf("Failed to initialise window\n");
#endif /* DEBUG_ENGINE */

    initialisation_complete = false;
  }

  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;
  }

  if (!initialisation_complete) {
    close_engine();

    return false;
  }

  GameEngine.running = true;
  GameEngine.delta = 0.0f;
  GameEngine.last_time = SDL_GetTicks64();

#ifdef DEBUG_ENGINE
  GameEngine.delta = 1.0f / 60.0f;
#endif /* DEBUG_ENGINE */

#ifdef DEBUG_ENGINE
  printf("Game initialised successfully\n");
#endif /* DEBUG_ENGINE */

  return true;
}

bool game_running() { return GameEngine.running; }

void close_engine() {
  destroy_asset_manager(&(GameEngine.asset_manager));

  destroy_object_store(&(GameEngine.object_store));

  destroy_window(&(GameEngine.window));

  GameEngine.last_time = 0.0f;

  GameEngine.delta = 0.0f;

  GameEngine.running = false;

  Mix_CloseAudio();

  Mix_Quit();

  TTF_Quit();

  IMG_Quit();

  SDL_Quit();

#ifdef DEBUG_ENGINE
  printf("Game closed successfully\n");
#endif /* DEBUG_ENGINE */
}

i64 get_time() { return SDL_GetTicks64(); }

ObjectID add_object(void *object, EventHandlerPtr event_handler,
                    UpdateFuncPtr update_func, RenderFuncPtr render_func) {
  if (!(GameEngine.running) || !(GameEngine.object_store)) {
    return -1;
  }

  return add_object_to_store(GameEngine.object_store, object, event_handler,
                             update_func, render_func);
}

void remove_object(ObjectID *id) {
  if (!(GameEngine.running) || !(GameEngine.object_store)) {
    return;
  }

  remove_object_from_store(GameEngine.object_store, id);
}

AssetID load_asset(const char *path, AssetType type) {
  return type == ASSET_TYPE_IMAGE
             ? load_asset_to_manager(GameEngine.asset_manager, path, type,
                                     GameEngine.window.renderer)
             : load_asset_to_manager(GameEngine.asset_manager, path, type,
                                     NULL);
}

void close_asset(AssetID *id) {
  if (*id < 0) {
    return;
  }

  remove_asset_from_manager(GameEngine.asset_manager, id);
}

WindowSize get_window_defined_size() { return GameEngine.window.defined_size; }

WindowSize get_window_real_size() { return GameEngine.window.real_size; }

WindowDrawingArea get_window_drawing_area() {
  return GameEngine.window.drawing_area;
}

void draw_rectangle(RenderRect rect, SDL_Color color) {
  draw_rect(GameEngine.window.renderer, color, rect.x, rect.y, rect.width,
            rect.height);
}

void fill_rectangle(RenderRect rect, SDL_Color color) {
  fill_rect(GameEngine.window.renderer, color, rect.x, rect.y, rect.width,
            rect.height);
}

void clip_render_rects_to_drawing_area(RenderRect *src, RenderRect *dest) {
  if (!dest) {
    return;
  }

  WindowDrawingArea area = get_window_drawing_area();

  // If the rectangle is completely out of bounds, set its width and height to 0
  if (dest->x > area.x + area.width || dest->x + dest->width < area.x ||
      dest->y > area.y + area.height || dest->y + dest->height < area.y) {
    if (src) {
      src->width = 0.0f;
      src->height = 0.0f;
    }

    dest->width = 0.0f;
    dest->height = 0.0f;

    return;
  }

  f32 x_offset = 0.0f;
  f32 y_offset = 0.0f;
  f32 x_clip = 0.0f;
  f32 y_clip = 0.0f;

  // If the rectangle is partially out of the horizontal bounds of the drawing
  // area, calculate how much of its width will be clipped
  if (dest->x < area.x) {
    // When an object goes out of the left border of the screen, we need to both
    // clip and offset the source and destination rectangles to ensure that the
    // object is rendered properly
    x_clip = x_offset = area.x - dest->x;
  } else if (dest->x + dest->width > area.x + area.width) {
    x_clip = (dest->x + dest->width) - (area.x + area.width);
  }

  // If the rectangle is partially out of the vertical bounds of the drawing
  // area, calculate how much of its height will be clipped
  if (dest->y < area.y) {
    // When an object goes out of the top border of the screen, we need to both
    // clip and offset the source and destination rectangles to ensure that the
    // object is rendered properly
    y_clip = y_offset = area.y - dest->y;
  } else if (dest->y + dest->height > area.y + area.height) {
    y_clip = (dest->y + dest->height) - (area.y + area.height);
  }

  if (src) {
    // Offset and clipping of source rectangle needs to be calculated based on
    // the ratio of the x_clip and y_clip variables to the width and height of
    // the destination rectangle respectively. This is because the source
    // rectangle's width and height might be different from the destination's
    src->x += ((x_offset / dest->width) * src->width);
    src->y += ((y_offset / dest->height) * src->height);
    src->width *= 1 - (x_clip / dest->width);
    src->height *= 1 - (y_clip / dest->height);
  }

  dest->x += x_offset;
  dest->y += y_offset;
  dest->width -= x_clip;
  dest->height -= y_clip;
}

RenderRect get_texture_asset_rect(AssetID id) {
  RenderRect rect = {0.0f, 0.0f, 0.0f, 0.0f};

  SDL_Texture *texture = get_texture(GameEngine.asset_manager, id);

  if (texture) {
    i32 w = 0;
    i32 h = 0;
    if (SDL_QueryTexture(texture, NULL, NULL, &w, &h) == 0) {
      rect.width = w;
      rect.height = h;
    }
  }

  return rect;
}

void render_texture_asset(AssetID id, RenderRect *src, RenderRect *dest) {
  if (id < 0) {
    return;
  }

  SDL_Texture *texture = get_texture(GameEngine.asset_manager, id);

  if (!texture) {
    return;
  }

  render_texture(GameEngine.window.renderer, texture, src, dest);
}

void modulate_texture_color(AssetID id, SDL_Color color) {
  if (id < 0) {
    return;
  }

  SDL_Texture *texture = get_texture(GameEngine.asset_manager, id);

  if (!texture) {
    return;
  }

  set_texture_color_modulation(texture, color);
}

void modulate_texture_alpha(AssetID id, u8 alpha) {
  if (id < 0) {
    return;
  }

  SDL_Texture *texture = get_texture(GameEngine.asset_manager, id);

  if (!texture) {
    return;
  }

  set_texture_alpha_modulation(texture, alpha);
}

TextSize get_text_size_from_font_asset(AssetID id, const char *text) {
  TextSize output = {};

  if (id < 0) {
    return output;
  }

  TTF_Font *font = get_font(GameEngine.asset_manager, id);
  if (!font) {
    return output;
  }

  TTF_SizeText(font, text, &(output.width), &(output.height));

  return output;
}

void render_text_with_font_asset(AssetID id, const char *text, f32 x, f32 y,
                                 SDL_Color color) {
  if (id < 0) {
    return;
  }

  TTF_Font *font = get_font(GameEngine.asset_manager, id);
  if (!font) {
    return;
  }

  SDL_Surface *surface = TTF_RenderText_Solid(font, text, color);
  if (!surface) {
    return;
  }

  // Get the width and height, in pixels, of the text rendered using the font
  i32 w = 0;
  i32 h = 0;
  TTF_SizeText(font, text, &w, &h);

  RenderRect rect = {x, y, w, h};

  render_surface(GameEngine.window.renderer, surface, &rect);

  SDL_FreeSurface(surface);
  surface = NULL;
}

void set_font_asset_size(AssetID id, u32 size) {
  if (id < 0) {
    return;
  }

  TTF_Font *font = get_font(GameEngine.asset_manager, id);
  if (!font) {
    return;
  }

  TTF_SetFontSize(font, size);
}

i8 play_audio_asset(AssetID id, i16 loops, bool fade_in,
                    u32 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, u8 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, u8 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, u8 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, u8 track,
                                   u32 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;
  }

  u64 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;
  }

  u64 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;
  }

  u64 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, u32 fade_length_in_ms) {
  if (id < 0) {
    return;
  }

  Mix_Chunk *chunk = get_audio_chunk(GameEngine.asset_manager, id);
  if (!chunk) {
    return;
  }

  u64 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);
    }
  }
}

i8 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, i8 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, i16 loops, bool fade_in,
                      u32 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, u32 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);
}

i8 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, i8 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(u32 fade_length_in_ms) {
  Mix_FadeOutMusic(fade_length_in_ms);
}

void set_playing_music_volume(i8 volume) { Mix_VolumeMusic(volume); }

bool is_music_playing() { return Mix_PlayingMusic(); }

void handle_events() {
  if (!(GameEngine.running)) {
    return;
  }

  while (SDL_PollEvent(&(GameEngine.event))) {
    switch (GameEngine.event.type) {
    case SDL_QUIT:
      GameEngine.running = false;
      break;
    }

    if (!GameEngine.object_store) {
      break;
    }

    handle_all_objects_events(GameEngine.object_store, &(GameEngine.event));
  }
}

void update() {
  if (!(GameEngine.running) || !(GameEngine.object_store)) {
    return;
  }

  u64 current_time = SDL_GetTicks64();

#ifndef DEBUG_ENGINE
  // Get the delta time in seconds since the SDL_GetTicks64() returns the
  // time in milliseconds
  GameEngine.delta = (current_time - GameEngine.last_time) / 1000.0f;
#endif /* !DEBUG_ENGINE */

  update_all_objects(GameEngine.object_store, GameEngine.delta);

  GameEngine.last_time = current_time;
}

void render() {
  if (!(GameEngine.running)) {
    return;
  }

  clear_window(&(GameEngine.window));

  if (GameEngine.object_store) {
    render_all_objects(GameEngine.object_store);
  }

  swap_render_buffers(&(GameEngine.window));
}