snakePlus/source/game_logic.cpp

#include "game_logic.h"

#include <algorithm>
#include <cstdlib>

#include <nds.h>
#include <consts.h>

void update_snake(GameState &state) {
  std::array<int, 3> headpos = state.snake.front();
  std::array<int, 3> newHead = headpos;

  if (state.snakeDirection == 0) {
    newHead = {headpos[0], headpos[1] - 1, state.snakeDirection};
  } else if (state.snakeDirection == 1) {
    newHead = {headpos[0] + 1, headpos[1], state.snakeDirection};
  } else if (state.snakeDirection == 2) {
    newHead = {headpos[0], headpos[1] + 1, state.snakeDirection};
  } else if (state.snakeDirection == 3) {
    newHead = {headpos[0] - 1, headpos[1], state.snakeDirection};
  }

  if (newHead[0] > X_MAX) {
    newHead[0] = 0;
  }
  if (newHead[1] > Y_MAX) {
    newHead[1] = 0;
  }
  if (newHead[0] < 0) {
    newHead[0] = X_MAX;
  }
  if (newHead[1] < 0) {
    newHead[1] = Y_MAX;
  }

  state.snake.push_front(newHead);
  state.snake.resize(state.snakelength);
}

bool check_collision_self(GameState &state) {
  if (state.snake.size() < 2 || state.gameOver) {
    return false;
  }

  const std::array<int, 3> headpos = state.snake.front();

  for (auto it = state.snake.begin() + 1; it != state.snake.end(); ++it) {
    if ((*it)[0] == headpos[0] && (*it)[1] == headpos[1]) {
      state.gameOver = true;
      return true;
    }
  }

  return false;
}

bool check_collision_apples(GameState &state) {
  const std::array<int, 3> headpos = state.snake.front();

  auto it =
      std::find_if(state.apples.begin(), state.apples.end(),
                   [&](const std::array<int, 2> &apple) {
                     return apple[0] == headpos[0] && apple[1] == headpos[1];
                   });

  if (it == state.apples.end()) {
    return false;
  }

  state.score += APPLE_SCORE;
  state.snakelength++;
  state.applesEaten++;
  state.apples.erase(it);
  return true;
}

bool check_collision_apples_rotten(GameState &state) {
  const std::array<int, 3> headpos = state.snake.front();

  auto it =
      std::find_if(state.bad_apples.begin(), state.bad_apples.end(),
                   [&](const std::array<int, 2> &apple) {
                     return apple[0] == headpos[0] && apple[1] == headpos[1];
                   });

  if (it == state.bad_apples.end()) {
    return false;
  }

  state.snakelength--;
  state.bad_apples.erase(it);
  if (state.snakelength < 2) {
    state.gameOver = true;
  }
  return true;
}

bool check_collision_apples_cursed(GameState &state) {
  const std::array<int, 3> headpos = state.snake.front();

  auto it =
      std::find_if(state.cursed_apples.begin(), state.cursed_apples.end(),
                   [&](const std::array<int, 2> &apple) {
                     return apple[0] == headpos[0] && apple[1] == headpos[1];
                   });

  if (it == state.cursed_apples.end()) {
    return false;
  }

  state.cursed_apples.erase(it);
  state.curseTicksRemaining = CURSE_DURATION_TICKS;
  return true;
}

void spawn_apples(GameState &state) {
  if (state.apples.size() < 1) {
    std::array<int, 2> apple = {rand() % (X_MAX + 1), rand() % (Y_MAX + 1)};
    state.apples.push_back(apple);
  }
}

void spawn_apples_rotten(GameState &state) {
  if ((state.ticks % 10 == 0) && state.hardMode && ((rand() % 10) < 10) &&
      (state.bad_apples.size() < 20)) {
    std::array<int, 2> badApple = {rand() % (X_MAX + 1), rand() % (Y_MAX + 1)};
    state.bad_apples.push_back(badApple);
  }
}

void spawn_apples_cursed(GameState &state) {
  if (state.cursed_apples.empty() && (state.ticks % 20 == 0) &&
      ((rand() % 5) == 0)) {
    std::array<int, 2> cursedApple = {rand() % (X_MAX + 1),
                                      rand() % (Y_MAX + 1)};
    state.cursed_apples.push_back(cursedApple);
  }
}

void tick_status_effects(GameState &state) {
  if (state.curseTicksRemaining > 0) {
    state.curseTicksRemaining--;
  }
}

uint8_t calculate_intensity_31(const GameState &state) {
  const uint16_t current_apples = state.applesEaten;
  const uint16_t apples =
      std::min<uint16_t>(current_apples, static_cast<uint16_t>(SPEED_APPLES_CAP));
  return static_cast<uint8_t>((static_cast<uint32_t>(apples) * 31U) /
                              static_cast<uint32_t>(SPEED_APPLES_CAP));
}

uint16_t calculate_timer_freq_mhz(const GameState &state) {
  const uint16_t base_mhz =
      state.hardMode ? SPEED_BASE_HARD_MHZ : SPEED_BASE_NORMAL_MHZ;
  const uint16_t max_mhz =
      state.hardMode ? SPEED_MAX_HARD_MHZ : SPEED_MAX_NORMAL_MHZ;
  const uint16_t current_apples = state.applesEaten;
  const uint16_t apples =
      std::min<uint16_t>(current_apples, static_cast<uint16_t>(SPEED_APPLES_CAP));
  const uint32_t diff = static_cast<uint32_t>(max_mhz - base_mhz);
  return static_cast<uint16_t>(
      base_mhz + ((static_cast<uint32_t>(apples) * diff) /
                  static_cast<uint32_t>(SPEED_APPLES_CAP)));
}

uint16_t calculate_timer_reload(const GameState &state) {
  const uint32_t freq_mhz = calculate_timer_freq_mhz(state);
  // Timer clock with ClockDivider_1024 is BUS_CLOCK >> 10 (32728 Hz)
  const uint32_t timer_clock_mhz = (BUS_CLOCK >> 10U) * 1000U;
  const uint32_t period_ticks = timer_clock_mhz / freq_mhz;
  return static_cast<uint16_t>(-static_cast<int32_t>(period_ticks));
}