Portable Retro Game Console

#include <Arduino.h>
#include <SPI.h>
#include <Adafruit_GFX.h>
#include <Adafruit_ST7789.h>

constexpr int TFT_CS = 19;
constexpr int TFT_DC = 16;
constexpr int TFT_RST = 17;
constexpr int BTN_UP = 13;
constexpr int BTN_DOWN = 14;
constexpr int BTN_LEFT = 25;
constexpr int BTN_RIGHT = 26;
constexpr int BTN_A = 27;
constexpr int BTN_B = 32;
constexpr int BTN_START = 33;
constexpr int BUZZER_PIN = 22;

constexpr int SCREEN_W = 320;
constexpr int SCREEN_H = 240;
constexpr int CELL = 10;
constexpr int FIELD_X = 10;
constexpr int FIELD_Y = 30;
constexpr int FIELD_W = 300;
constexpr int FIELD_H = 200;
constexpr int COLS = FIELD_W / CELL;
constexpr int ROWS = FIELD_H / CELL;
constexpr int MAX_SNAKE = COLS * ROWS;
constexpr uint16_t BG = ST77XX_BLACK;
constexpr uint16_t SNAKE = ST77XX_GREEN;
constexpr uint16_t FOOD = ST77XX_RED;

Adafruit_ST7789 tft(TFT_CS, TFT_DC, TFT_RST);

struct Cell { int8_t x; int8_t y; };
Cell snake[MAX_SNAKE];
Cell food;
int snakeLength = 4;
int dx = 1;
int dy = 0;
int score = 0;
bool paused = false;
bool gameOver = false;
unsigned long lastMove = 0;
const unsigned long MOVE_MS = 120;

bool wasPressed(int pin) {
  static bool previous[40] = {false};
  bool now = digitalRead(pin) == LOW;
  bool pressed = now && !previous[pin];
  previous[pin] = now;
  return pressed;
}

void beep(uint16_t frequency, uint16_t duration) {
  tone(BUZZER_PIN, frequency, duration);
}

void drawCell(const Cell &c, uint16_t color) {
  tft.fillRect(FIELD_X + c.x * CELL + 1, FIELD_Y + c.y * CELL + 1, CELL - 2, CELL - 2, color);
}

bool snakeContains(int x, int y) {
  for (int i = 0; i < snakeLength; ++i) {
    if (snake[i].x == x && snake[i].y == y) return true;
  }
  return false;
}

void placeFood() {
  do {
    food.x = random(COLS);
    food.y = random(ROWS);
  } while (snakeContains(food.x, food.y));
  drawCell(food, FOOD);
}

void drawScore() {
  tft.fillRect(0, 0, SCREEN_W, 28, ST77XX_BLACK);
  tft.setTextColor(ST77XX_CYAN, ST77XX_BLACK);
  tft.setTextSize(2);
  tft.setCursor(10, 6);
  tft.print("RETRO SNAKE  ");
  tft.print(score);
}

void resetGame() {
  tft.fillScreen(BG);
  tft.drawRect(FIELD_X - 1, FIELD_Y - 1, FIELD_W + 2, FIELD_H + 2, ST77XX_BLUE);
  snakeLength = 4;
  score = 0;
  dx = 1;
  dy = 0;
  paused = false;
  gameOver = false;
  for (int i = 0; i < snakeLength; ++i) {
    snake[i] = {static_cast<int8_t>(12 - i), 10};
    drawCell(snake[i], SNAKE);
  }
  drawScore();
  placeFood();
  beep(880, 80);
}

void showGameOver() {
  tft.fillRect(55, 92, 210, 58, ST77XX_BLACK);
  tft.drawRect(55, 92, 210, 58, ST77XX_RED);
  tft.setTextColor(ST77XX_RED, ST77XX_BLACK);
  tft.setTextSize(2);
  tft.setCursor(82, 103);
  tft.print("GAME OVER");
  tft.setTextColor(ST77XX_WHITE, ST77XX_BLACK);
  tft.setTextSize(1);
  tft.setCursor(77, 130);
  tft.print("START pour rejouer");
  beep(180, 280);
}

void handleControls() {
  if (wasPressed(BTN_START)) {
    if (gameOver) resetGame();
    else {
      paused = !paused;
      beep(paused ? 400 : 700, 50);
    }
  }
  if (wasPressed(BTN_UP) && dy != 1) { dx = 0; dy = -1; }
  if (wasPressed(BTN_DOWN) && dy != -1) { dx = 0; dy = 1; }
  if (wasPressed(BTN_LEFT) && dx != 1) { dx = -1; dy = 0; }
  if (wasPressed(BTN_RIGHT) && dx != -1) { dx = 1; dy = 0; }
  if (wasPressed(BTN_A)) { paused = false; beep(1000, 35); }
  if (wasPressed(BTN_B)) { paused = true; beep(400, 35); }
}

void moveSnake() {
  Cell next = {static_cast<int8_t>(snake[0].x + dx), static_cast<int8_t>(snake[0].y + dy)};
  if (next.x < 0 || next.x >= COLS || next.y < 0 || next.y >= ROWS || snakeContains(next.x, next.y)) {
    gameOver = true;
    showGameOver();
    return;
  }
  bool ate = next.x == food.x && next.y == food.y;
  Cell tail = snake[snakeLength - 1];
  if (ate && snakeLength < MAX_SNAKE) {
    for (int i = snakeLength; i > 0; --i) snake[i] = snake[i - 1];
    ++snakeLength;
  } else {
    for (int i = snakeLength - 1; i > 0; --i) snake[i] = snake[i - 1];
  }
  snake[0] = next;
  if (ate) {
    ++score;
    drawScore();
    beep(1200, 55);
    placeFood();
  } else {
    drawCell(tail, BG);
  }
  drawCell(snake[0], SNAKE);
}

void setup() {
  const int buttons[] = {BTN_UP, BTN_DOWN, BTN_LEFT, BTN_RIGHT, BTN_A, BTN_B, BTN_START};
  for (int pin : buttons) pinMode(pin, INPUT_PULLUP);
  pinMode(BUZZER_PIN, OUTPUT);
  randomSeed(esp_random());
  tft.init(240, 320);
  tft.setRotation(1);
  resetGame();
}

void loop() {
  handleControls();
  unsigned long now = millis();
  if (!paused && !gameOver && now - lastMove >= MOVE_MS) {
    lastMove = now;
    moveSnake();
  }
  delay(5);
}