rust-roguelike-tutorial/chapter-28-drunkards-walk/src/map_builders/common.rs

use super::{Map, Rect, TileType};
use std::cmp::{max, min};
use std::collections::HashMap;

pub fn apply_room_to_map(map : &mut Map, room : &Rect) {
    for y in room.y1 +1 ..= room.y2 {
        for x in room.x1 + 1 ..= room.x2 {
            let idx = map.xy_idx(x, y);
            if idx > 0 && idx < ((map.width * map.height)-1) as usize {
                map.tiles[idx] = TileType::Floor;
            }
        }
    }
}

pub fn apply_horizontal_tunnel(map : &mut Map, x1:i32, x2:i32, y:i32) {
    for x in min(x1,x2) ..= max(x1,x2) {
        let idx = map.xy_idx(x, y);
        if idx > 0 && idx < map.width as usize * map.height as usize {
            map.tiles[idx as usize] = TileType::Floor;
        }
    }
}

pub fn apply_vertical_tunnel(map : &mut Map, y1:i32, y2:i32, x:i32) {
    for y in min(y1,y2) ..= max(y1,y2) {
        let idx = map.xy_idx(x, y);
        if idx > 0 && idx < map.width as usize * map.height as usize {
            map.tiles[idx as usize] = TileType::Floor;
        }
    }
}

/// Searches a map, removes unreachable areas and returns the most distant tile.
pub fn remove_unreachable_areas_returning_most_distant(map : &mut Map, start_idx : usize) -> usize {
    map.populate_blocked();
    let map_starts : Vec<i32> = vec![start_idx as i32];
    let dijkstra_map = rltk::DijkstraMap::new(map.width, map.height, &map_starts , map, 200.0);
    let mut exit_tile = (0, 0.0f32);
    for (i, tile) in map.tiles.iter_mut().enumerate() {
        if *tile == TileType::Floor {
            let distance_to_start = dijkstra_map.map[i];
            // We can't get to this tile - so we'll make it a wall
            if distance_to_start == std::f32::MAX {
                *tile = TileType::Wall;
            } else {
                // If it is further away than our current exit candidate, move the exit
                if distance_to_start > exit_tile.1 {
                    exit_tile.0 = i;
                    exit_tile.1 = distance_to_start;
                }
            }
        }
    }

    exit_tile.0
}

/// Generates a Voronoi/cellular noise map of a region, and divides it into spawn regions.
#[allow(clippy::map_entry)]
pub fn generate_voronoi_spawn_regions(map: &Map, rng : &mut rltk::RandomNumberGenerator) -> HashMap<i32, Vec<usize>> {
    let mut noise_areas : HashMap<i32, Vec<usize>> = HashMap::new();
    let mut noise = rltk::FastNoise::seeded(rng.roll_dice(1, 65536) as u64);
    noise.set_noise_type(rltk::NoiseType::Cellular);
    noise.set_frequency(0.08);
    noise.set_cellular_distance_function(rltk::CellularDistanceFunction::Manhattan);

    for y in 1 .. map.height-1 {
        for x in 1 .. map.width-1 {
            let idx = map.xy_idx(x, y);
            if map.tiles[idx] == TileType::Floor {
                let cell_value_f = noise.get_noise(x as f32, y as f32) * 10240.0;
                let cell_value = cell_value_f as i32;

                if noise_areas.contains_key(&cell_value) {
                    noise_areas.get_mut(&cell_value).unwrap().push(idx);
                } else {
                    noise_areas.insert(cell_value, vec![idx]);
                }
            }
        }
    }

    noise_areas
}