SnakeDL3/src/main.c

#define SDL_MAIN_USE_CALLBACKS 1
#include <SDL3/SDL.h>
#include <SDL3/SDL_main.h>

#define FPS 60

static SDL_Window *window = NULL;
static SDL_Renderer *renderer = NULL;

static int window_width = 640;
static int window_height = 480;
static int grid_width = 32;
static int grid_height = 24;

static Uint64 last;

enum TILES { EMPTY, SNAKE, FRUIT };
enum PARTS { TAIL, HEAD, BODY };

typedef enum DIRECTION { LEFT, RIGHT, UP, DOWN } DIRECTION;

typedef struct State {
  int *grid;
  DIRECTION player_face;
  SDL_FRect *r;
} State;

void log_game_grid(int *game_grid) {
  char *buf = SDL_malloc(sizeof(char) * grid_width * 2);
  for (int i = 0; i < grid_height; i++) {
    for (int j = 0; j < grid_width; j++) {
      buf[2 * j] = '0' + game_grid[i * grid_width + j];
      buf[2 * j + 1] = ' ';
    }
    buf[2 * grid_width] = '\0';
    SDL_Log("%s", buf);
  }
  SDL_free(buf);
}

void set_grid_at(int *grid, int row, int col, int value) { grid[row * grid_width + col] = value; }

int get_grid_at(int *grid, int row, int col) { return grid[row * grid_width + col]; }

SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[]) {
  if (!SDL_Init(SDL_INIT_VIDEO)) {
    SDL_Log("Couldn't initialize SDL: %s", SDL_GetError());
    return SDL_APP_FAILURE;
  }

  if (!SDL_CreateWindowAndRenderer("examples/renderer/clear", window_width, window_height, 0,
                                   &window, &renderer)) {
    SDL_Log("Couldn't create window/renderer: %s", SDL_GetError());
    return SDL_APP_FAILURE;
  }

  int *game_grid = SDL_malloc(sizeof(int) * grid_width * grid_height);
  for (int i = 0; i < grid_height; i++) {
    for (int j = 0; j < grid_width; j++) {
      set_grid_at(game_grid, i, j, EMPTY);
    }
  }

  set_grid_at(game_grid, 12, 16, SNAKE);
  set_grid_at(game_grid, 4, 12, FRUIT);
  set_grid_at(game_grid, 18, 5, FRUIT);

  SDL_FRect *rect2 = SDL_malloc(sizeof(SDL_FRect));
  rect2->y = 240;
  rect2->x = 0;
  rect2->w = 100;
  rect2->h = 100;

  State *state = SDL_malloc(sizeof(State));
  state->grid = game_grid;
  state->player_face = UP;
  state->r = rect2;
  *appstate = state;

  last = SDL_GetTicksNS();

  return SDL_APP_CONTINUE;
}

SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event) {
  if ((event->type == SDL_EVENT_KEY_UP && event->key.scancode == SDL_SCANCODE_ESCAPE) ||
      event->type == SDL_EVENT_QUIT) {
    return SDL_APP_SUCCESS;
  }
  return SDL_APP_CONTINUE;
}

SDL_AppResult SDL_AppIterate(void *appstate) {
  State *stateptr = appstate;
  int *game_grid = stateptr->grid;
  Uint64 delta = SDL_GetTicksNS() - last;
  double duration = (double)delta / (FPS * 1000);

  SDL_SetRenderDrawColorFloat(renderer, 0, 0, 0, SDL_ALPHA_OPAQUE_FLOAT);
  SDL_RenderClear(renderer);

  SDL_FRect rect;
  rect.w = (float)window_width / grid_width;
  rect.h = (float)window_height / grid_height;
  for (int i = 0; i < grid_height; i++) {
    for (int j = 0; j < grid_width; j++) {
      switch (get_grid_at(game_grid, i, j)) {
      case EMPTY:
        SDL_SetRenderDrawColorFloat(renderer, 0, 0, 0, SDL_ALPHA_OPAQUE_FLOAT);
        break;
      case SNAKE:
        SDL_SetRenderDrawColorFloat(renderer, 255, 255, 255, SDL_ALPHA_OPAQUE_FLOAT);
        break;
      case FRUIT:
        SDL_SetRenderDrawColorFloat(renderer, 255, 0, 0, SDL_ALPHA_OPAQUE_FLOAT);
        break;
      }
      rect.x = j * rect.w;
      rect.y = i * rect.h;
      SDL_RenderFillRect(renderer, &rect);
    }
  }

  SDL_FRect *rect2 = stateptr->r;
  rect2->x += 5 * (double)delta / 1000000;
  SDL_Log("%f %f %f %f", rect2->x, rect2->y, rect2->w, rect2->h);
  SDL_SetRenderDrawColorFloat(renderer, 0, 255, 0, SDL_ALPHA_OPAQUE_FLOAT);
  SDL_RenderFillRect(renderer, rect2);

  SDL_RenderPresent(renderer);

  last = SDL_GetTicksNS();

  return SDL_APP_CONTINUE;
}

void SDL_AppQuit(void *appstate, SDL_AppResult result) {
  /* SDL will clean up the window/renderer for us. */
}