raycaster/src/algos/maze.cpp

#include <fmt/core.h>
#include <string>
#include "algos/rand.hpp"
#include "constants.hpp"
#include "algos/maze.hpp"

using std::string;
using matrix::Matrix;

namespace maze {
  inline size_t rand(size_t i, size_t j) {
    if(i < j) {
      return Random::uniform(i, j);
    } else if(j < i) {
      return Random::uniform(j, i);
    } else {
      return i;
    }
  }

  inline bool complete(Matrix& maze) {
    size_t width = matrix::width(maze);
    size_t height = matrix::height(maze);

    for(size_t row = 1; row < height; row += 2) {
      for(size_t col = 1; col < width; col += 2) {
        if(maze[row][col] != 0) return false;
      }
    }

    return true;
  }

  std::vector<Point> neighborsAB(Matrix& maze, Point on) {
    std::vector<Point> result;

    std::array<Point, 4> points{{
      {on.x, on.y - 2},
        {on.x, on.y + 2},
        {on.x - 2, on.y},
        {on.x + 2, on.y}
    }};

    for(auto point : points) {
      if(matrix::inbounds(maze, point.x, point.y)) {
        result.push_back(point);
      }
    }

    return result;
  }

  std::vector<Point> neighbors(Matrix& maze, Point on) {
    std::vector<Point> result;

    std::array<Point, 4> points{{
      {on.x, on.y - 2},
        {on.x, on.y + 2},
        {on.x - 2, on.y},
        {on.x + 2, on.y}
    }};

    for(auto point : points) {
      if(matrix::inbounds(maze, point.x, point.y)) {
        if(maze[point.y][point.x] == WALL_VALUE) {
          result.push_back(point);
        }
      }
    }

    return result;
  }

  inline std::pair<Point, Point> find_coord(Matrix& maze) {
    size_t width = matrix::width(maze);
    size_t height = matrix::height(maze);

    for(size_t y = 1; y < height; y += 2) {
      for(size_t x = 1; x < width; x += 2) {
        if(maze[y][x] == WALL_VALUE) {
          auto found = neighborsAB(maze, {x, y});

          for(auto point : found) {
            if(maze[point.y][point.x] == 0) {
              return {{x, y}, point};
            }
          }
        }
      }
    }

    matrix::dump("BAD MAZE", maze);
    dbc::sentinel("failed to find coord?");
  }

  bool Builder::room_should_exist(Room& room, bool allow_dupes) {
    if(!matrix::inbounds($walls, room.x, room.y) ||
      !matrix::inbounds($walls, room.x + room.width, room.y + room.height))
    {
      return false;
    }

    if(room.overlaps($no_rooms_region)) {
      return false;
    }

    for(auto& other : $rooms) {
      bool is_duped = allow_dupes ? room == other : room != other;

      if(is_duped && room.overlaps(other)) {
        return false;
      }
    }

    // it's in the map and doesn't collide with another room
    return true;
  }

  void Builder::randomize_rooms(size_t room_size) {
    // use those dead ends to randomly place rooms
    for(auto at : $dead_ends) {
      // skip 50% of them
      if(Random::uniform(0,1) == 0) continue;

      // get the room corners randomized
      std::array<Point, 4> starts{{
        {at.x, at.y}, // top left
          {at.x - room_size + 1, at.y}, // top right
          {at.x - room_size + 1, at.y - room_size + 1}, // bottom right
          {at.x, at.y - room_size + 1} // bottom left
      }};


      size_t offset = Random::uniform(0, 3);

      // BUG: this still accidentally merges rooms
      for(size_t i = 0; i < starts.size(); i++) {
        size_t index = (i + offset) % starts.size();
        Room cur{starts[index].x, starts[index].y, room_size, room_size};

        // if it's out of bounds skip it
        if(room_should_exist(cur)) {
          $rooms.push_back(cur);
          break;
        }
      }
    }
  }

  void Builder::clear() {
    matrix::assign($walls, WALL_VALUE);
  }

  void Builder::divide(Point start, Point end) {
    for(matrix::line it{start, end}; it.next();) {
      $walls[it.y][it.x] = 0;
      $walls[it.y+1][it.x] = 0;
    }
  }

  void Builder::hunt_and_kill(Point on) {
    if($rooms.size() > 0) place_rooms();

    while(!complete($walls)) {
      auto n = neighbors($walls, on);

      if(n.size() == 0) {
        // no neighbors, must be dead end
        add_dead_end(on);
        auto t = find_coord($walls);
        on = t.first;
        $walls[on.y][on.x] = 0;
        size_t row = (on.y + t.second.y) / 2;
        size_t col = (on.x + t.second.x) / 2;
        $walls[row][col] = 0;
      } else {
        // found neighbors, pick random one
        auto nb = n[rand(size_t(0), n.size() - 1)];
        $walls[nb.y][nb.x] = 0;

        size_t row = (nb.y + on.y) / 2;
        size_t col = (nb.x + on.x) / 2;
        $walls[row][col] = 0;
        on = nb;
      }
    }
  }

  void Builder::place_rooms() {
    for(auto& room : $rooms) {
      for(matrix::rectangle it{$walls, room.x, room.y, room.width, room.height}; it.next();) {
        $walls[it.y][it.x] = 0;
      }
    }
  }

  void Builder::inner_donut(float outer_rad, float inner_rad) {
    size_t x = matrix::width($walls) / 2;
    size_t y = matrix::height($walls) / 2;

    for(matrix::circle it{$walls, {x, y}, outer_rad}; it.next();)
    {
      for(int x = it.left; x < it.right; x++) {
        $walls[it.y][x] = 0;
      }
    }

    for(matrix::circle it{$walls, {x, y}, inner_rad}; it.next();)
    {
      for(int x = it.left; x < it.right; x++) {
        $walls[it.y][x] = 1;
      }
    }
  }

  void Builder::remove_dead_ends() {
    dbc::check($dead_ends.size() > 0, "you have to run an algo first, no dead_ends to remove");

    for(auto at : $dead_ends) {
      for(matrix::compass it{$walls, at.x, at.y}; it.next();) {
        if($walls[it.y][it.x] == SPACE_VALUE) {
          punch_dead_end(at.x, at.y, it.x, it.y);
          break;
        }
      }
    }
  }

  void Builder::dump(const std::string& msg) {
    auto wall_copy = $walls;

    // mark the rooms too
    for(auto& room : $rooms) {
      for(matrix::rectangle it{wall_copy, room.x, room.y, room.width, room.height};
          it.next();)
      {
        if(wall_copy[it.y][it.x] == 0 && wall_copy[it.y][it.x] != 3) {
          wall_copy[it.y][it.x] = WALL_PATH_LIMIT;
        }
      }
    }

    // mark dead ends
    for(auto at : $dead_ends) {
      // don't mark dead ends if there's something else there
      wall_copy[at.y][at.x] = 32;
    }

    for(auto [at, _] : $doors) {
      wall_copy[at.y][at.x] = 0xd;
    }

    matrix::dump(msg, wall_copy);
  }

  void Builder::enclose() {
    size_t width = matrix::width($walls);
    size_t height = matrix::height($walls);

    for(matrix::perimeter it{0, 0, width, height}; it.next();) {
      $walls[it.y][it.x] = WALL_VALUE;
      Point at{it.x,it.y};
      if($doors.contains(at)) $doors.erase(at);
    }
  }

  void Builder::open_box(size_t outer_size) {
    size_t center_x = matrix::width($walls) / 2;
    size_t center_y = matrix::height($walls) / 2;

    // compensate for the box's border now
    outer_size++;

    // this can't be right but for now it's working
    size_t x = center_x - outer_size;
    size_t y = center_y - outer_size;
    // BUG: is the + 1 here because the bug in perimeter
    size_t width = (outer_size * 2) + 1;
    size_t height = (outer_size * 2) + 1;

    for(matrix::perimeter p{x, y, width, height}; p.next();) {
      for(matrix::compass it{$walls, p.x, p.y}; it.next();) {
        if($ends_map.contains({it.x, it.y})) {
          $walls[y][x] = 0;
          break;
        }
      }
    }
  }

  void Builder::make_doors() {
    for(auto room : $rooms) {
      // walk the outer wall looking for an emergent door
      int possible_doors = 0;
      Point last_door{0,0};

      matrix::perimeter it{room.x - 1, room.y - 1, room.width + 2, room.height + 2};

      while(it.next()) {
        if($walls[it.y][it.x] == SPACE_VALUE) {
          last_door = {it.x, it.y};
          possible_doors++;
        }
      }

      // if only found one then make that an actual door
      if(possible_doors == 1) {
        $doors.insert_or_assign(last_door, true);
        continue;
      }

      // no natural door found, need to make one
      it = {room.x - 1, room.y - 1, room.width + 2, room.height + 2};
      last_door = {0,0};
      bool found_door = false;

      while(it.next()) {
        for(matrix::compass near_door{$walls, it.x, it.y}; near_door.next();) {
          // skip the wall parts
          if($walls[near_door.y][near_door.x] == WALL_VALUE) continue;

          if($ends_map.contains({near_door.x, near_door.y})) {
            if(room.contains({near_door.x, near_door.y})) {
              // last ditch effort is use the internal dead end
              last_door = {it.x, it.y};
            } else {
              $walls[it.y][it.x] = SPACE_VALUE;
              $doors.insert_or_assign({it.x, it.y}, true);
              found_door = true;
              break;
            }
          }
        }
      }

      if(!found_door && last_door.x != 0) {
        // didn't find an external door so punch one at the dead end
        $walls[last_door.y][last_door.x] = SPACE_VALUE;
        $doors.insert_or_assign({last_door.x, last_door.y}, true);
      }
    }
  }

  void Builder::inner_box(size_t outer_size, size_t inner_size) {
    size_t x = matrix::width($walls) / 2;
    size_t y = matrix::height($walls) / 2;

    for(matrix::box it{$walls, x, y, outer_size}; it.next();)
    {
      $walls[it.y][it.x] = 0;
    }

    for(matrix::box it{$walls, x, y, inner_size}; it.next();)
    {
      $walls[it.y][it.x] = 1;
    }

    // make a fake room that blocks others
    $no_rooms_region = {x - outer_size, y - outer_size, outer_size * 2 + 1, outer_size * 2 + 1};
  }

  void Builder::add_dead_end(Point at) {
    // doing this ensures no dupes, if it's !inserted then it already existed
    auto [_, inserted] = $ends_map.insert_or_assign(at, true);

    // so skip it, it isn't new
    if(inserted) {
      $dead_ends.push_back(at);
    }
  }

  bool Builder::validate() {
    size_t width = matrix::width($walls);
    size_t height = matrix::height($walls);

    // no rooms can overlap
    for(auto& room : $rooms) {
      if(!room_should_exist(room)) return false;
    }

    for(matrix::perimeter it{0, 0, width, height}; it.next();) {
      if($ends_map.contains({it.x, it.y})) return false;
      if($doors.contains({it.x, it.y})) return false;
    }

    if($rooms.size() == 1) return true;

    // initial path test can just use one room then look for
    // any cells that are empty in the walls map but unpathed in the paths
    Room test_room = $rooms.at(0);
    Point test{test_room.x, test_room.y};
    $paths.set_target(test);
    $paths.compute_paths($walls);
    // $paths.dump("AFTER COMPUTE");
    $paths.clear_target(test);

    for(matrix::each_cell it{$walls}; it.next();) {
      if($walls[it.y][it.x] == SPACE_VALUE &&
          $paths.$paths[it.y][it.x] == WALL_PATH_LIMIT) {
        return false;
      }
    }

    return true;
  }

  void Builder::punch_dead_end(size_t at_x, size_t at_y, size_t x, size_t y) {
    int diff_x = at_x - x;
    int diff_y = at_y - y;
    $walls[at_y + diff_y][at_x + diff_x] = SPACE_VALUE;
  }

  bool Builder::repair() {
    // possible fixes
    // go through each dead end and remove until it works
    // go through each room and add a door until it works
    // only find rooms that are unpathable and fix them
    // walk the path deleting dead ends at the end of the path
    std::vector<Point> removed_ends;
    bool now_valid = false;

    for(auto& at : $dead_ends) {
      // punch a hole for this dead end
      for(matrix::compass it{$walls, at.x, at.y}; it.next();) {
        if($walls[it.y][it.x] == SPACE_VALUE) {
          punch_dead_end(at.x, at.y, it.x, it.y);
          removed_ends.push_back({it.x, it.y});
          break;
        }
      }

      // if that validates it then done
      if(validate()) {
        now_valid = true;
        fmt::println("MID dead_end removed={}, total={}, %={}",
          removed_ends.size(), $dead_ends.size(),
          float(removed_ends.size()) / float($dead_ends.size()));
        break;
      }
    }

    // now go back and see if we can add any back
    int added_back = 0;
    for(auto& at : removed_ends) {
      $walls[at.y][at.x] = WALL_VALUE;

      if(!validate()) {
        $walls[at.y][at.x] = SPACE_VALUE;
      } else {
        added_back++;
      }
    }

    enclose();
    now_valid = validate();

    fmt::println("FINAL now_valid={} added_back={} removed={}, total={}, %={}",
        now_valid, added_back, removed_ends.size() - added_back, $dead_ends.size(),
        float(removed_ends.size() - added_back) / float($dead_ends.size()));

    // didn't find a way to make it valid
    return now_valid;
  }
}