分层/构建器链

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在过去的几章中，我们介绍了程序化生成中一个重要的概念：链式构建器。我们很高兴地构建地图，调用波函数坍缩来改变地图，调用我们的 PrefabBuilder 再次改变它，等等。本章将稍微形式化这个过程，扩展它，并为你留下一个框架，让你能够清晰地通过链式连接概念来构建新地图。

基于构建器的接口

构建器链式调用是程序化生成地图的一种非常深刻的方法，它为我们提供了一个机会来清理我们目前构建的很多代码。我们想要一个类似于我们使用 Specs 构建实体的接口：一个构建器，我们可以在其上不断链式调用构建器，并将其作为“执行器”返回 - 准备好构建地图。我们还希望阻止构建器做超过一件事 - 它们应该只做一件事，并把它做好（这是一个好的设计原则；它使调试更容易，并减少重复）。

构建器主要有两种类型：只生成地图的（并且只运行一次才有意义），以及修改现有地图的。我们将分别将它们命名为 InitialMapBuilder 和 MetaMapBuilder。

这给了我们一个想要采用的语法概念：

我们的 Builder 应该有：
- 一个初始构建器 (Initial Builder)。
- n 个元构建器 (Meta Builder)，按顺序运行。

那么，构建器应该有一个接受第一个地图的 start_with 方法，以及用于链式连接构建器的额外的 with 方法，这是有道理的。构建器应该存储在一个容器中，该容器保留它们被添加的顺序 - 向量是显而易见的选择。

不再让单个构建器负责设置它们的前置组件也是有道理的；理想情况下，除了它所做的事情之外，构建器不应该必须知道任何关于过程的事情。因此，我们需要抽象这个过程，并支持快照（以便您可以查看程序化生成过程）。

共享地图状态 - `BuilderMap`

与其让每个构建器定义它们自己的共享数据副本，不如将共享数据放在一个地方 - 并在需要时在链中传递它，这将更有意义。因此，我们将首先在 map_builders/mod.rs 中定义一些新的结构和接口。首先，我们将创建 BuilderMap：

#![allow(unused)]
fn main() {
pub struct BuilderMap {
    pub spawn_list : Vec<(usize, String)>,
    pub map : Map,
    pub starting_position : Option<Position>,
    pub rooms: Option<Vec<Rect>>,
    pub history : Vec<Map>
}
}

你会注意到，这包含了我们一直在构建到每个地图构建器中的所有数据 - 仅此而已。它是有意通用的 - 我们将把它传递给构建器，并让他们处理它。请注意，所有字段都是 公共的 - 这是因为我们正在传递它，并且很有可能任何接触它的东西都需要访问它的全部或部分内容。

BuilderMap 还需要方便进行快照的任务，以便调试器查看我们处理算法时的地图。我们将在 BuilderMap 中放入一个函数 - 用于处理快照开发：

#![allow(unused)]
fn main() {
impl BuilderMap {
    fn take_snapshot(&mut self) {
        if SHOW_MAPGEN_VISUALIZER {
            let mut snapshot = self.map.clone();
            for v in snapshot.revealed_tiles.iter_mut() {
                *v = true;
            }
            self.history.push(snapshot);
        }
    }
}
}

这与我们一直在混入构建器的 take_snapshot 代码相同。由于我们正在使用地图构建知识的中央存储库，我们可以提升它以应用于所有我们的构建器。

`BuilderChain` - 管理地图创建的主构建器

以前，我们传递了 MapBuilder 类，每个类都能够构建之前的地图。由于我们已经得出结论，这是一个糟糕的想法，并定义了我们想要的语法，我们将创建一个替代品。BuilderChain 是一个主构建器 - 它控制整个构建过程。为此，我们将添加 BuilderChain 类型：

#![allow(unused)]
fn main() {
pub struct BuilderChain {
    starter: Option<Box<dyn InitialMapBuilder>>,
    builders: Vec<Box<dyn MetaMapBuilder>>,
    pub build_data : BuilderMap
}
}

这是一个更复杂的结构，所以让我们过一遍：

starter 是一个 Option，所以我们知道是否存在一个。没有第一步（不引用其他地图的地图）将是一个错误条件，因此我们将跟踪它。我们正在引用一个新的 trait，InitialMapBuilder；我们稍后会介绍它。
builders 是 MetaMapBuilders 的向量，另一个新的 trait（同样 - 我们稍后会介绍它）。这些是操作先前地图结果的构建器。
build_data 是一个公共变量（任何人都可以读/写它），包含我们刚刚创建的 BuilderMap。

我们将实现一些函数来支持它。首先，一个 构造函数：

#![allow(unused)]
fn main() {
impl BuilderChain {
    pub fn new(new_depth : i32) -> BuilderChain {
        BuilderChain{
            starter: None,
            builders: Vec::new(),
            build_data : BuilderMap {
                spawn_list: Vec::new(),
                map: Map::new(new_depth),
                starting_position: None,
                rooms: None,
                history : Vec::new()
            }
        }
    }
    ...
}

这非常简单：它创建了一个新的 BuilderChain，所有内容都使用默认值。现在，让我们允许我们的用户向链中添加 起始地图。（起始地图是不需要先前地图作为输入的第一步，并生成可用的地图结构，我们可以对其进行修改）：

#![allow(unused)]
fn main() {
...
pub fn start_with(&mut self, starter : Box<dyn InitialMapBuilder>) {
    match self.starter {
        None => self.starter = Some(starter),
        Some(_) => panic!("You can only have one starting builder.")
    };
}
...
}

这里有一个新概念：panic!。如果用户尝试添加第二个起始构建器，我们将崩溃 - 因为这没有任何意义。你只是简单地覆盖你之前的步骤，这是一个巨大的时间浪费！我们还将允许用户添加元构建器：

#![allow(unused)]
fn main() {
...
pub fn with(&mut self, metabuilder : Box<dyn MetaMapBuilder>) {
    self.builders.push(metabuilder);
}
...
}

这非常简单：我们只需将元构建器添加到构建器向量中。由于向量保持您添加到它们的顺序，因此您的操作将保持适当的排序。最后，我们将实现一个实际构建地图的函数：

#![allow(unused)]
fn main() {
pub fn build_map(&mut self, rng : &mut rltk::RandomNumberGenerator) {
    match &mut self.starter {
        None => panic!("Cannot run a map builder chain without a starting build system"),
        Some(starter) => {
            // 构建起始地图
            starter.build_map(rng, &mut self.build_data);
        }
    }

    // 依次构建额外的层
    for metabuilder in self.builders.iter_mut() {
        metabuilder.build_map(rng, &mut self.build_data);
    }
}
}

让我们在这里逐步了解一下：

我们 match 了我们的起始地图。如果没有起始地图，我们会 panic - 并崩溃程序，并显示一条消息，提示您必须设置一个起始构建器。
我们在起始地图上调用 build_map。
对于每个元构建器，我们在其上调用 build_map - 按照指定的顺序。

这不是一个糟糕的语法！它应该使我们能够将构建器链接在一起，并为构建复杂的分层地图提供所需的概览。

新的 Traits - `InitialMapBuilder` 和 `MetaMapBuilder`

让我们看一下我们定义的两个 trait 接口，InitialMapBuilder 和 MetaMapBuilder。我们将它们设为单独的类型，以强制用户只选择一个起始构建器，而不是尝试将任何起始构建器放入修改层列表中。它们的实现是相同的：

#![allow(unused)]
fn main() {
pub trait InitialMapBuilder {
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap);
}

pub trait MetaMapBuilder {
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap);
}
}

build_map 接受一个随机数生成器（这样我们就不会到处创建新的生成器了！），以及我们正在处理的 BuilderMap 的可变引用。因此，我们不是让每个构建器可选地调用前一个构建器，而是在处理状态时传递状态。

生成函数

我们还需要实现我们的生成系统：

#![allow(unused)]
fn main() {
pub fn spawn_entities(&mut self, ecs : &mut World) {
    for entity in self.build_data.spawn_list.iter() {
        spawner::spawn_entity(ecs, &(&entity.0, &entity.1));
    }
}
}

这几乎与我们之前在 MapBuilder 中的生成器代码相同，但我们是从 build_data 结构中的 spawn_list 中生成的。否则，它是相同的。

随机构建器 - 第一步

最后，我们将修改 random_builder 以使用我们的 SimpleMapBuilder 和一些新类型来分解创建步骤：

#![allow(unused)]
fn main() {
pub fn random_builder(new_depth: i32, rng: &mut rltk::RandomNumberGenerator) -> BuilderChain {
    let mut builder = BuilderChain::new(new_depth);
    builder.start_with(SimpleMapBuilder::new());
    builder.with(RoomBasedSpawner::new());
    builder.with(RoomBasedStartingPosition::new());
    builder.with(RoomBasedStairs::new());
    builder
}
}

请注意，我们现在正在使用 RandomNumberGenerator 参数。这是因为我们想使用全局 RNG，而不是一直创建新的 RNG。这样，如果调用者设置了“种子” - 它将应用于世界生成。这计划成为未来章节的主题。我们现在还返回 BuilderChain 而不是 boxed trait - 我们将 messy boxing/dynamic dispatch 隐藏在实现内部，因此调用者不必担心它。这里还有两个新类型：RoomBasedSpawner 和 RoomBasedStartingPosition - 以及 SimpleMapBuilder 的更改后的构造函数（它不再接受深度参数）。我们稍后会介绍这一点 - 但首先，让我们处理由于新接口而导致的主程序更改。

看起来不错的界面 - 但你破坏了东西！

我们现在拥有了我们想要的接口 - 系统如何与世界交互的良好地图。不幸的是，世界仍然期望我们之前的设置 - 所以我们需要修复它。在 main.rs 中，我们需要更新我们的 generate_world_map 函数以使用新接口：

#![allow(unused)]
fn main() {
fn generate_world_map(&mut self, new_depth : i32) {
    self.mapgen_index = 0;
    self.mapgen_timer = 0.0;
    self.mapgen_history.clear();
    let mut rng = self.ecs.write_resource::<rltk::RandomNumberGenerator>();
    let mut builder = map_builders::random_builder(new_depth, &mut rng);
    builder.build_map(&mut rng);
    std::mem::drop(rng);
    self.mapgen_history = builder.build_data.history.clone();
    let player_start;
    {
        let mut worldmap_resource = self.ecs.write_resource::<Map>();
        *worldmap_resource = builder.build_data.map.clone();
        player_start = builder.build_data.starting_position.as_mut().unwrap().clone();
    }

    // 生成坏人
    builder.spawn_entities(&mut self.ecs);
}

我们重置 mapgen_index、mapgen_timer 和 mapgen_history，以便进度查看器从头开始运行。
我们从 ECS World 获取 RNG。
我们使用新接口创建一个新的 random_builder，并传递随机数生成器。
我们告诉它从链中构建新地图，也利用 RNG。
我们在 RNG 上调用 std::mem::drop。这停止了对它的“借用” - 因此我们也不再借用 self。这防止了代码的后续阶段出现借用检查器错误。
我们将地图构建器历史记录克隆到我们自己的世界历史记录副本中。我们复制它，这样我们就不会破坏构建器。
我们将 player_start 设置为构建器确定的起始位置的克隆。请注意，我们正在调用 unwrap - 因此起始位置的 Option 必须在此时有一个值，否则我们将崩溃。这是故意的：我们宁愿崩溃，知道我们忘记设置起始点，也不愿程序在未知/混乱的状态下运行。
我们调用 spawn_entities 来填充地图。

修改 SimpleMapBuilder

我们可以大大简化 SimpleMapBuilder（使其名副其实！）。这是新代码：

#![allow(unused)]
fn main() {
use super::{InitialMapBuilder, BuilderMap, Rect, apply_room_to_map,
    apply_horizontal_tunnel, apply_vertical_tunnel };
use rltk::RandomNumberGenerator;

pub struct SimpleMapBuilder {}

impl InitialMapBuilder for SimpleMapBuilder {
    #[allow(dead_code)]
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap) {
        self.rooms_and_corridors(rng, build_data);
    }
}

impl SimpleMapBuilder {
    #[allow(dead_code)]
    pub fn new() -> Box<SimpleMapBuilder> {
        Box::new(SimpleMapBuilder{})
    }

    fn rooms_and_corridors(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        const MAX_ROOMS : i32 = 30;
        const MIN_SIZE : i32 = 6;
        const MAX_SIZE : i32 = 10;
        let mut rooms : Vec<Rect> = Vec::new();

        for i in 0..MAX_ROOMS {
            let w = rng.range(MIN_SIZE, MAX_SIZE);
            let h = rng.range(MIN_SIZE, MAX_SIZE);
            let x = rng.roll_dice(1, build_data.map.width - w - 1) - 1;
            let y = rng.roll_dice(1, build_data.map.height - h - 1) - 1;
            let new_room = Rect::new(x, y, w, h);
            let mut ok = true;
            for other_room in rooms.iter() {
                if new_room.intersect(other_room) { ok = false }
            }
            if ok {
                apply_room_to_map(&mut build_data.map, &new_room);
                build_data.take_snapshot();

                if !rooms.is_empty() {
                    let (new_x, new_y) = new_room.center();
                    let (prev_x, prev_y) = rooms[i as usize -1].center();
                    if rng.range(0,2) == 1 {
                        apply_horizontal_tunnel(&mut build_data.map, prev_x, new_x, prev_y);
                        apply_vertical_tunnel(&mut build_data.map, prev_y, new_y, new_x);
                    } else {
                        apply_vertical_tunnel(&mut build_data.map, prev_y, new_y, prev_x);
                        apply_horizontal_tunnel(&mut build_data.map, prev_x, new_x, new_y);
                    }
                }

                rooms.push(new_room);
                build_data.take_snapshot();
            }
        }
        build_data.rooms = Some(rooms);
    }
}
}

这基本上与旧的 SimpleMapBuilder 相同，但有一些更改：

请注意，我们只应用了 InitialMapBuilder trait - MapBuilder 不复存在了。
我们也没有设置起始位置或生成实体 - 这些现在是链中其他构建器的职权范围。我们基本上将其提炼为仅房间构建算法。
我们将 build_data.rooms 设置为 Some(rooms)。并非所有算法都支持房间 - 因此我们的 trait 将 Option 设置为 None，直到我们填充它为止。由于 SimpleMapBuilder 完全是关于房间的 - 我们填充它。

基于房间的生成

在 map_builders 目录中创建一个新文件 room_based_spawner.rs。我们将在这里应用旧 SimpleMapBuilder 中的仅房间填充系统：

#![allow(unused)]
fn main() {
use super::{MetaMapBuilder, BuilderMap, spawner};
use rltk::RandomNumberGenerator;

pub struct RoomBasedSpawner {}

impl MetaMapBuilder for RoomBasedSpawner {
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap)  {
        self.build(rng, build_data);
    }
}

impl RoomBasedSpawner {
    #[allow(dead_code)]
    pub fn new() -> Box<RoomBasedSpawner> {
        Box::new(RoomBasedSpawner{})
    }

    fn build(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        if let Some(rooms) = &build_data.rooms {
            for room in rooms.iter().skip(1) {
                spawner::spawn_room(&build_data.map, rng, room, build_data.map.depth, &mut build_data.spawn_list);
            }
        } else {
            panic!("Room Based Spawning only works after rooms have been created");
        }
    }
}
}

在这个子模块中，我们正在实现 MetaMapBuilder：这个构建器要求您已经有一个地图。在 build 中，我们从 SimpleMapBuilder 中复制了旧的基于房间的生成代码，并对其进行了修改以在构建器的 rooms 结构上运行。为此，我们使用 if let 来获取 Option 的内部值；如果没有，那么我们 panic!，程序退出，并声明基于房间的生成仅在您有房间的情况下才有效。

我们将功能减少到仅一个任务：如果有房间，我们在其中生成怪物。

基于房间的起始位置

这与基于房间的生成非常相似，但将玩家放置在第一个房间中 - 就像以前在 SimpleMapBuilder 中一样。在 map_builders 中创建一个新文件 room_based_starting_position：

#![allow(unused)]
fn main() {
use super::{MetaMapBuilder, BuilderMap, Position};
use rltk::RandomNumberGenerator;

pub struct RoomBasedStartingPosition {}

impl MetaMapBuilder for RoomBasedStartingPosition {
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap)  {
        self.build(rng, build_data);
    }
}

impl RoomBasedStartingPosition {
    #[allow(dead_code)]
    pub fn new() -> Box<RoomBasedStartingPosition> {
        Box::new(RoomBasedStartingPosition{})
    }

    fn build(&mut self, _rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        if let Some(rooms) = &build_data.rooms {
            let start_pos = rooms[0].center();
            build_data.starting_position = Some(Position{ x: start_pos.0, y: start_pos.1 });
        } else {
            panic!("Room Based Staring Position only works after rooms have been created");
        }
    }
}
}

基于房间的楼梯

这也非常类似于我们在 SimpleMapBuilder 中生成出口楼梯的方式。创建一个新文件 room_based_stairs.rs：

#![allow(unused)]
fn main() {
use super::{MetaMapBuilder, BuilderMap, TileType};
use rltk::RandomNumberGenerator;

pub struct RoomBasedStairs {}

impl MetaMapBuilder for RoomBasedStairs {
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap)  {
        self.build(rng, build_data);
    }
}

impl RoomBasedStairs {
    #[allow(dead_code)]
    pub fn new() -> Box<RoomBasedStairs> {
        Box::new(RoomBasedStairs{})
    }

    fn build(&mut self, _rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        if let Some(rooms) = &build_data.rooms {
            let stairs_position = rooms[rooms.len()-1].center();
            let stairs_idx = build_data.map.xy_idx(stairs_position.0, stairs_position.1);
            build_data.map.tiles[stairs_idx] = TileType::DownStairs;
            build_data.take_snapshot();
        } else {
            panic!("Room Based Stairs only works after rooms have been created");
        }
    }
}
}

将它们放在一起，用新框架制作一个简单的地图

让我们再次看一下 random_builder：

#![allow(unused)]
fn main() {
let mut builder = BuilderChain::new(new_depth);
builder.start_with(SimpleMapBuilder::new());
builder.with(RoomBasedSpawner::new());
builder.with(RoomBasedStartingPosition::new());
builder.with(RoomBasedStairs::new());
builder
}

既然我们已经完成了所有步骤，这应该是有意义的：

我们从使用 SimpleMapBuilder 生成器生成的地图开始。
我们使用 元构建器 RoomBasedSpawner 修改地图，以在房间中生成实体。
我们再次使用 元构建器 RoomBasedStartingPosition 修改地图，以便从第一个房间开始。
再次，我们使用 元构建器 RoomBasedStairs 修改地图，以在最后一个房间中放置向下楼梯。

如果你现在 cargo run 项目，你将看到很多关于未使用代码的警告 - 但游戏应该可以玩，只有我们第一节中的简单地图。您可能想知道 为什么 我们付出了这么多努力来保持事物相同；希望随着我们清理更多构建器，这一点会变得清晰！

清理 BSP 地牢构建器

再次，我们可以认真清理地图构建器！这是新版本的 bsp_dungeon.rs：

#![allow(unused)]
fn main() {
use super::{InitialMapBuilder, BuilderMap, Map, Rect, apply_room_to_map,
    TileType, draw_corridor};
use rltk::RandomNumberGenerator;

pub struct BspDungeonBuilder {
    rects: Vec<Rect>,
}

impl InitialMapBuilder for BspDungeonBuilder {
    #[allow(dead_code)]
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap) {
        self.build(rng, build_data);
    }
}

impl BspDungeonBuilder {
    #[allow(dead_code)]
    pub fn new() -> Box<BspDungeonBuilder> {
        Box::new(BspDungeonBuilder{
            rects: Vec::new(),
        })
    }

    fn build(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        let mut rooms : Vec<Rect> = Vec::new();
        self.rects.clear();
        self.rects.push( Rect::new(2, 2, build_data.map.width-5, build_data.map.height-5) ); // 从单个地图大小的矩形开始
        let first_room = self.rects[0];
        self.add_subrects(first_room); // 划分第一个房间

        // 最多 240 次，我们获得一个随机矩形并划分它。如果有可能在那里挤出一个房间，
        // 我们放置它并将其添加到房间列表。
        let mut n_rooms = 0;
        while n_rooms < 240 {
            let rect = self.get_random_rect(rng);
            let candidate = self.get_random_sub_rect(rect, rng);

            if self.is_possible(candidate, &build_data.map) {
                apply_room_to_map(&mut build_data.map, &candidate);
                rooms.push(candidate);
                self.add_subrects(rect);
                build_data.take_snapshot();
            }

            n_rooms += 1;
        }

        // 现在我们对房间进行排序
        rooms.sort_by(|a,b| a.x1.cmp(&b.x1) );

        // 现在我们需要走廊
        for i in 0..rooms.len()-1 {
            let room = rooms[i];
            let next_room = rooms[i+1];
            let start_x = room.x1 + (rng.roll_dice(1, i32::abs(room.x1 - room.x2))-1);
            let start_y = room.y1 + (rng.roll_dice(1, i32::abs(room.y1 - room.y2))-1);
            let end_x = next_room.x1 + (rng.roll_dice(1, i32::abs(next_room.x1 - next_room.x2))-1);
            let end_y = next_room.y1 + (rng.roll_dice(1, i32::abs(next_room.y1 - next_room.y2))-1);
            draw_corridor(&mut build_data.map, start_x, start_y, end_x, end_y);
            build_data.take_snapshot();
        }
        build_data.rooms = Some(rooms);
    }

    fn add_subrects(&mut self, rect : Rect) {
        let width = i32::abs(rect.x1 - rect.x2);
        let height = i32::abs(rect.y1 - rect.y2);
        let half_width = i32::max(width / 2, 1);
        let half_height = i32::max(height / 2, 1);

        self.rects.push(Rect::new( rect.x1, rect.y1, half_width, half_height ));
        self.rects.push(Rect::new( rect.x1, rect.y1 + half_height, half_width, half_height ));
        self.rects.push(Rect::new( rect.x1 + half_width, rect.y1, half_width, half_height ));
        self.rects.push(Rect::new( rect.x1 + half_width, rect.y1 + half_height, half_width, half_height ));
    }

    fn get_random_rect(&mut self, rng : &mut RandomNumberGenerator) -> Rect {
        if self.rects.len() == 1 { return self.rects[0]; }
        let idx = (rng.roll_dice(1, self.rects.len() as i32)-1) as usize;
        self.rects[idx]
    }

    fn get_random_sub_rect(&self, rect : Rect, rng : &mut RandomNumberGenerator) -> Rect {
        let mut result = rect;
        let rect_width = i32::abs(rect.x1 - rect.x2);
        let rect_height = i32::abs(rect.y1 - rect.y2);

        let w = i32::max(3, rng.roll_dice(1, i32::min(rect_width, 10))-1) + 1;
        let h = i32::max(3, rng.roll_dice(1, i32::min(rect_height, 10))-1) + 1;

        result.x1 += rng.roll_dice(1, 6)-1;
        result.y1 += rng.roll_dice(1, 6)-1;
        result.x2 = result.x1 + w;
        result.y2 = result.y1 + h;

        result
    }

    fn is_possible(&self, rect : Rect, map : &Map) -> bool {
        let mut expanded = rect;
        expanded.x1 -= 2;
        expanded.x2 += 2;
        expanded.y1 -= 2;
        expanded.y2 += 2;

        let mut can_build = true;

        for y in expanded.y1 ..= expanded.y2 {
            for x in expanded.x1 ..= expanded.x2 {
                if x > map.width-2 { can_build = false; }
                if y > map.height-2 { can_build = false; }
                if x < 1 { can_build = false; }
                if y < 1 { can_build = false; }
                if can_build {
                    let idx = map.xy_idx(x, y);
                    if map.tiles[idx] != TileType::Wall {
                        can_build = false;
                    }
                }
            }
        }

        can_build
    }
}
}

就像 SimpleMapBuilder 一样，我们已经剥离了所有非房间构建代码，使其成为更简洁的代码。我们正在引用构建器的 build_data 结构，而不是制作我们自己的所有内容的副本 - 代码的核心部分在很大程度上是相同的。

现在您可以修改 random_builder 以制作此地图类型：

#![allow(unused)]
fn main() {
let mut builder = BuilderChain::new(new_depth);
builder.start_with(BspDungeonBuilder::new());
builder.with(RoomBasedSpawner::new());
builder.with(RoomBasedStartingPosition::new());
builder.with(RoomBasedStairs::new());
builder
}

如果你现在 cargo run，你将获得一个基于 BspDungeonBuilder 的地牢。看看你是如何重用生成器、起始位置和楼梯代码的？这绝对比旧版本有所改进 - 如果您更改一个，它现在可以帮助多个构建器！

再次针对 BSP 内部

再次，我们可以极大地清理构建器 - 这次是 BspInteriorBuilder。这是 bsp_interior.rs 的代码：

#![allow(unused)]
fn main() {
use super::{InitialMapBuilder, BuilderMap, Rect, TileType, draw_corridor};
use rltk::RandomNumberGenerator;

const MIN_ROOM_SIZE : i32 = 8;

pub struct BspInteriorBuilder {
    rects: Vec<Rect>
}

impl InitialMapBuilder for BspInteriorBuilder {
    #[allow(dead_code)]
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap) {
        self.build(rng, build_data);
    }
}

impl BspInteriorBuilder {
    #[allow(dead_code)]
    pub fn new() -> Box<BspInteriorBuilder> {
        Box::new(BspInteriorBuilder{
            rects: Vec::new()
        })
    }

    fn build(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        let mut rooms : Vec<Rect> = Vec::new();
        self.rects.clear();
        self.rects.push( Rect::new(1, 1, build_data.map.width-2, build_data.map.height-2) ); // 从单个地图大小的矩形开始
        let first_room = self.rects[0];
        self.add_subrects(first_room, rng); // 划分第一个房间

        let rooms_copy = self.rects.clone();
        for r in rooms_copy.iter() {
            let room = *r;
            //room.x2 -= 1;
            //room.y2 -= 1;
            rooms.push(room);
            for y in room.y1 .. room.y2 {
                for x in room.x1 .. room.x2 {
                    let idx = build_data.map.xy_idx(x, y);
                    if idx > 0 && idx < ((build_data.map.width * build_data.map.height)-1) as usize {
                        build_data.map.tiles[idx] = TileType::Floor;
                    }
                }
            }
            build_data.take_snapshot();
        }

        // 现在我们需要走廊
        for i in 0..rooms.len()-1 {
            let room = rooms[i];
            let next_room = rooms[i+1];
            let start_x = room.x1 + (rng.roll_dice(1, i32::abs(room.x1 - room.x2))-1);
            let start_y = room.y1 + (rng.roll_dice(1, i32::abs(room.y1 - room.y2))-1);
            let end_x = next_room.x1 + (rng.roll_dice(1, i32::abs(next_room.x1 - next_room.x2))-1);
            let end_y = next_room.y1 + (rng.roll_dice(1, i32::abs(next_room.y1 - next_room.y2))-1);
            draw_corridor(&mut build_data.map, start_x, start_y, end_x, end_y);
            build_data.take_snapshot();
        }

        build_data.rooms = Some(rooms);
    }

    fn add_subrects(&mut self, rect : Rect, rng : &mut RandomNumberGenerator) {
        // 从列表中删除最后一个矩形
        if !self.rects.is_empty() {
            self.rects.remove(self.rects.len() - 1);
        }

        // 计算边界
        let width  = rect.x2 - rect.x1;
        let height = rect.y2 - rect.y1;
        let half_width = width / 2;
        let half_height = height / 2;

        let split = rng.roll_dice(1, 4);

        if split <= 2 {
            // 水平分割
            let h1 = Rect::new( rect.x1, rect.y1, half_width-1, height );
            self.rects.push( h1 );
            if half_width > MIN_ROOM_SIZE { self.add_subrects(h1, rng); }
            let h2 = Rect::new( rect.x1 + half_width, rect.y1, half_width, height );
            self.rects.push( h2 );
            if half_width > MIN_ROOM_SIZE { self.add_subrects(h2, rng); }
        } else {
            // 垂直分割
            let v1 = Rect::new( rect.x1, rect.y1, width, half_height-1 );
            self.rects.push(v1);
            if half_height > MIN_ROOM_SIZE { self.add_subrects(v1, rng); }
            let v2 = Rect::new( rect.x1, rect.y1 + half_height, width, half_height );
            self.rects.push(v2);
            if half_height > MIN_ROOM_SIZE { self.add_subrects(v2, rng); }
        }
    }
}
}

您可以通过修改 random_builder 来测试它：

#![allow(unused)]
fn main() {
let mut builder = BuilderChain::new(new_depth);
builder.start_with(BspInteriorBuilder::new());
builder.with(RoomBasedSpawner::new());
builder.with(RoomBasedStartingPosition::new());
builder.with(RoomBasedStairs::new());
builder
}

cargo run 现在将带您进入一个内部构建器。

细胞自动机

您现在应该理解这里的基本思想了 - 我们正在将构建器分解为小块，并为地图类型实现适当的 traits。查看细胞自动机地图，您会发现我们做事的方式略有不同：

我们像往常一样制作地图。这显然属于 CellularAutomataBuilder。
我们搜索靠近中间的起始点。这看起来应该是一个单独的步骤。
我们搜索地图中无法到达的区域并剔除它们。这看起来也是一个单独的步骤。
我们将出口放置在远离起始位置的地方。这也是一个不同的算法步骤。

好消息是，其中最后三个步骤在许多其他构建器中使用 - 因此实现它们将使我们能够重用代码，而不会不断重复自己。坏消息是，如果我们使用现有的基于房间的步骤运行我们的细胞自动机构建器，它将崩溃 - 我们没有房间！

因此，我们将从构建基本的地图构建器开始。像其他构建器一样，这主要只是重新排列代码以适应新的 trait 方案。这是新的 cellular_automata.rs 文件：

#![allow(unused)]
fn main() {
use super::{InitialMapBuilder, BuilderMap, TileType};
use rltk::RandomNumberGenerator;

pub struct CellularAutomataBuilder {}

impl InitialMapBuilder for CellularAutomataBuilder {
    #[allow(dead_code)]
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap) {
        self.build(rng, build_data);
    }
}

impl CellularAutomataBuilder {
    #[allow(dead_code)]
    pub fn new() -> Box<CellularAutomataBuilder> {
        Box::new(CellularAutomataBuilder{})
    }

    #[allow(clippy::map_entry)]
    fn build(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        // 首先，我们完全随机化地图，将其 55% 设置为地板。
        for y in 1..build_data.map.height-1 {
            for x in 1..build_data.map.width-1 {
                let roll = rng.roll_dice(1, 100);
                let idx = build_data.map.xy_idx(x, y);
                if roll > 55 { build_data.map.tiles[idx] = TileType::Floor }
                else { build_data.map.tiles[idx] = TileType::Wall }
            }
        }
        build_data.take_snapshot();

        // 现在我们迭代地应用细胞自动机规则
        for _i in 0..15 {
            let mut newtiles = build_data.map.tiles.clone();

            for y in 1..build_data.map.height-1 {
                for x in 1..build_data.map.width-1 {
                    let idx = build_data.map.xy_idx(x, y);
                    let mut neighbors = 0;
                    if build_data.map.tiles[idx - 1] == TileType::Wall { neighbors += 1; }
                    if build_data.map.tiles[idx + 1] == TileType::Wall { neighbors += 1; }
                    if build_data.map.tiles[idx - build_data.map.width as usize] == TileType::Wall { neighbors += 1; }
                    if build_data.map.tiles[idx + build_data.map.width as usize] == TileType::Wall { neighbors += 1; }
                    if build_data.map.tiles[idx - (build_data.map.width as usize - 1)] == TileType::Wall { neighbors += 1; }
                    if build_data.map.tiles[idx - (build_data.map.width as usize + 1)] == TileType::Wall { neighbors += 1; }
                    if build_data.map.tiles[idx + (build_data.map.width as usize - 1)] == TileType::Wall { neighbors += 1; }
                    if build_data.map.tiles[idx + (build_data.map.width as usize + 1)] == TileType::Wall { neighbors += 1; }

                    if neighbors > 4 || neighbors == 0 {
                        newtiles[idx] = TileType::Wall;
                    }
                    else {
                        newtiles[idx] = TileType::Floor;
                    }
                }
            }

            build_data.map.tiles = newtiles.clone();
            build_data.take_snapshot();
        }
    }
}
}

非房间起始点

我们完全有可能实际上并不想从地图中间开始。这样做提供了很多机会（并有助于确保连通性），但也许您宁愿玩家跋涉穿过很多地图，而减少选择错误方向的机会。如果玩家到达地图的一端并从另一端离开，也许您的故事更有意义。让我们实现一个起始位置系统，该系统采用 首选的 起始点，并选择最近的有效瓦片。创建 area_starting_points.rs：

#![allow(unused)]
fn main() {
use super::{MetaMapBuilder, BuilderMap, Position, TileType};
use rltk::RandomNumberGenerator;

#[allow(dead_code)]
pub enum XStart { LEFT, CENTER, RIGHT }

#[allow(dead_code)]
pub enum YStart { TOP, CENTER, BOTTOM }

pub struct AreaStartingPosition {
    x : XStart,
    y : YStart
}

impl MetaMapBuilder for AreaStartingPosition {
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap)  {
        self.build(rng, build_data);
    }
}

impl AreaStartingPosition {
    #[allow(dead_code)]
    pub fn new(x : XStart, y : YStart) -> Box<AreaStartingPosition> {
        Box::new(AreaStartingPosition{
            x, y
        })
    }

    fn build(&mut self, _rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        let seed_x;
        let seed_y;

        match self.x {
            XStart::LEFT => seed_x = 1,
            XStart::CENTER => seed_x = build_data.map.width / 2,
            XStart::RIGHT => seed_x = build_data.map.width - 2
        }

        match self.y {
            YStart::TOP => seed_y = 1,
            YStart::CENTER => seed_y = build_data.map.height / 2,
            YStart::BOTTOM => seed_y = build_data.map.height - 2
        }

        let mut available_floors : Vec<(usize, f32)> = Vec::new();
        for (idx, tiletype) in build_data.map.tiles.iter().enumerate() {
            if *tiletype == TileType::Floor {
                available_floors.push(
                    (
                        idx,
                        rltk::DistanceAlg::PythagorasSquared.distance2d(
                            rltk::Point::new(idx as i32 % build_data.map.width, idx as i32 / build_data.map.width),
                            rltk::Point::new(seed_x, seed_y)
                        )
                    )
                );
            }
        }
        if available_floors.is_empty() {
            panic!("No valid floors to start on");
        }

        available_floors.sort_by(|a,b| a.1.partial_cmp(&b.1).unwrap());

        let start_x = available_floors[0].0 as i32 % build_data.map.width;
        let start_y = available_floors[0].0 as i32 / build_data.map.width;

        build_data.starting_position = Some(Position{x : start_x, y: start_y});
    }
}
}

我们已经介绍了足够的样板代码，不需要再次介绍了 - 所以让我们逐步了解 build 函数：

我们接受几个 enum 类型：X 轴和 Y 轴上的首选位置。
因此，我们将 seed_x 和 seed_y 设置为最接近指定位置的点。
我们遍历整个地图，将地板瓦片添加到 available_floors - 并计算到首选起始点的距离。
我们对可用瓦片列表进行排序，以便距离较小的瓦片排在前面。
我们选择列表中的第一个。

请注意，如果没有地板，我们也会 panic!。

这里最棒的部分是，这将适用于任何地图类型 - 它搜索可以站立的地板，并尝试找到最近的起始点。

剔除无法到达的区域

我们之前在剔除无法从起始点到达的区域方面取得了不错的成功。因此，让我们将其形式化为自己的元构建器。创建 cull_unreachable.rs：

#![allow(unused)]
fn main() {
use super::{MetaMapBuilder, BuilderMap, TileType};
use rltk::RandomNumberGenerator;

pub struct CullUnreachable {}

impl MetaMapBuilder for CullUnreachable {
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap)  {
        self.build(rng, build_data);
    }
}

impl CullUnreachable {
    #[allow(dead_code)]
    pub fn new() -> Box<CullUnreachable> {
        Box::new(CullUnreachable{})
    }

    fn build(&mut self, _rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        let starting_pos = build_data.starting_position.as_ref().unwrap().clone();
        let start_idx = build_data.map.xy_idx(
            starting_pos.x,
            starting_pos.y
        );
        build_data.map.populate_blocked();
        let map_starts : Vec<usize> = vec![start_idx];
        let dijkstra_map = rltk::DijkstraMap::new(build_data.map.width as usize, build_data.map.height as usize, &map_starts , &build_data.map, 1000.0);
        for (i, tile) in build_data.map.tiles.iter_mut().enumerate() {
            if *tile == TileType::Floor {
                let distance_to_start = dijkstra_map.map[i];
                // 我们无法到达此瓦片 - 因此我们将其设为墙壁
                if distance_to_start == std::f32::MAX {
                    *tile = TileType::Wall;
                }
            }
        }
    }
}
}

您会注意到这几乎与 common.rs 中的 remove_unreachable_areas_returning_most_distant 相同，但没有返回 Dijkstra 地图。这就是意图：我们删除玩家无法到达的区域，并且只做这件事。

基于 Voronoi 的生成

我们还需要复制基于 Voronoi 的生成的功能。创建 voronoi_spawning.rs：

#![allow(unused)]
fn main() {
use super::{MetaMapBuilder, BuilderMap, TileType, spawner};
use rltk::RandomNumberGenerator;
use std::collections::HashMap;

pub struct VoronoiSpawning {}

impl MetaMapBuilder for VoronoiSpawning {
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap)  {
        self.build(rng, build_data);
    }
}

impl VoronoiSpawning {
    #[allow(dead_code)]
    pub fn new() -> Box<VoronoiSpawning> {
        Box::new(VoronoiSpawning{})
    }

    #[allow(clippy::map_entry)]
    fn build(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        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 .. build_data.map.height-1 {
            for x in 1 .. build_data.map.width-1 {
                let idx = build_data.map.xy_idx(x, y);
                if build_data.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]);
                    }
                }
            }
        }

        // 生成实体
        for area in noise_areas.iter() {
            spawner::spawn_region(&build_data.map, rng, area.1, build_data.map.depth, &mut build_data.spawn_list);
        }
    }
}
}

这几乎与我们在各种构建器中调用的 common.rs 中的代码相同，只是进行了修改以在构建器链/构建器地图框架内工作。

生成一个遥远的出口

另一个常用的代码片段生成了关卡的 Dijkstra 地图，从玩家的入口点开始 - 并使用该地图将出口放置在离玩家最远的位置。这在 common.rs 中，我们经常调用它。我们将把这个变成地图构建步骤；创建 map_builders/distant_exit.rs：

#![allow(unused)]
fn main() {
use super::{MetaMapBuilder, BuilderMap, TileType};
use rltk::RandomNumberGenerator;

pub struct DistantExit {}

impl MetaMapBuilder for DistantExit {
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap)  {
        self.build(rng, build_data);
    }
}

impl DistantExit {
    #[allow(dead_code)]
    pub fn new() -> Box<DistantExit> {
        Box::new(DistantExit{})
    }

    fn build(&mut self, _rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        let starting_pos = build_data.starting_position.as_ref().unwrap().clone();
        let start_idx = build_data.map.xy_idx(
            starting_pos.x,
            starting_pos.y
        );
        build_data.map.populate_blocked();
        let map_starts : Vec<usize> = vec![start_idx];
        let dijkstra_map = rltk::DijkstraMap::new(build_data.map.width as usize, build_data.map.height as usize, &map_starts , &build_data.map, 1000.0);
        let mut exit_tile = (0, 0.0f32);
        for (i, tile) in build_data.map.tiles.iter_mut().enumerate() {
            if *tile == TileType::Floor {
                let distance_to_start = dijkstra_map.map[i];
                if distance_to_start != std::f32::MAX {
                    // 如果它比我们当前的出口候选更远，则移动出口
                    if distance_to_start > exit_tile.1 {
                        exit_tile.0 = i;
                        exit_tile.1 = distance_to_start;
                    }
                }
            }
        }

        // 放置楼梯
        let stairs_idx = exit_tile.0;
        build_data.map.tiles[stairs_idx] = TileType::DownStairs;
        build_data.take_snapshot();
    }
}
}

同样，这是我们之前使用过的相同代码 - 只是进行了调整以匹配新接口，因此我们不会详细介绍。

测试细胞自动机

我们终于把所有部件都放在一起了，让我们测试一下。在 random_builder 中，我们将使用新的构建器链：

#![allow(unused)]
fn main() {
let mut builder = BuilderChain::new(new_depth);
builder.start_with(CellularAutomataBuilder::new());
builder.with(AreaStartingPosition::new(XStart::CENTER, YStart::CENTER));
builder.with(CullUnreachable::new());
builder.with(VoronoiSpawning::new());
builder.with(DistantExit::new());
builder
}

如果您现在 cargo run，您将可以在细胞自动机生成的地图中玩游戏。

更新醉汉漫步

您应该对我们现在正在做的事情有一个很好的了解，因此我们将略过对 drunkard.rs 的更改：

#![allow(unused)]
fn main() {
use super::{InitialMapBuilder, BuilderMap, TileType, Position, paint, Symmetry};
use rltk::RandomNumberGenerator;

#[derive(PartialEq, Copy, Clone)]
#[allow(dead_code)]
pub enum DrunkSpawnMode { StartingPoint, Random }

pub struct DrunkardSettings {
    pub spawn_mode : DrunkSpawnMode,
    pub drunken_lifetime : i32,
    pub floor_percent: f32,
    pub brush_size: i32,
    pub symmetry: Symmetry
}

pub struct DrunkardsWalkBuilder {
    settings : DrunkardSettings
}

impl InitialMapBuilder for DrunkardsWalkBuilder {
    #[allow(dead_code)]
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap) {
        self.build(rng, build_data);
    }
}

impl DrunkardsWalkBuilder {
    #[allow(dead_code)]
    pub fn new(settings: DrunkardSettings) -> DrunkardsWalkBuilder {
        DrunkardsWalkBuilder{
            settings
        }
    }

    #[allow(dead_code)]
    pub fn open_area() -> Box<DrunkardsWalkBuilder> {
        Box::new(DrunkardsWalkBuilder{
            settings : DrunkardSettings{
                spawn_mode: DrunkSpawnMode::StartingPoint,
                drunken_lifetime: 400,
                floor_percent: 0.5,
                brush_size: 1,
                symmetry: Symmetry::None
            }
        })
    }

    #[allow(dead_code)]
    pub fn open_halls() -> Box<DrunkardsWalkBuilder> {
        Box::new(DrunkardsWalkBuilder{
            settings : DrunkardSettings{
                spawn_mode: DrunkSpawnMode::Random,
                drunken_lifetime: 400,
                floor_percent: 0.5,
                brush_size: 1,
                symmetry: Symmetry::None
            },
        })
    }

    #[allow(dead_code)]
    pub fn winding_passages() -> Box<DrunkardsWalkBuilder> {
        Box::new(DrunkardsWalkBuilder{
            settings : DrunkardSettings{
                spawn_mode: DrunkSpawnMode::Random,
                drunken_lifetime: 100,
                floor_percent: 0.4,
                brush_size: 1,
                symmetry: Symmetry::None
            },
        })
    }

    #[allow(dead_code)]
    pub fn fat_passages() -> Box<DrunkardsWalkBuilder> {
        Box::new(DrunkardsWalkBuilder{
            settings : DrunkardSettings{
                spawn_mode: DrunkSpawnMode::Random,
                drunken_lifetime: 100,
                floor_percent: 0.4,
                brush_size: 2,
                symmetry: Symmetry::None
            },
        })
    }

    #[allow(dead_code)]
    pub fn fearful_symmetry() -> Box<DrunkardsWalkBuilder> {
        Box::new(DrunkardsWalkBuilder{
            settings : DrunkardSettings{
                spawn_mode: DrunkSpawnMode::Random,
                drunken_lifetime: 100,
                floor_percent: 0.4,
                brush_size: 1,
                symmetry: Symmetry::Both
            },
        })
    }

    fn build(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        // 设置中心起始点
        let starting_position = Position{ x: build_data.map.width / 2, y: build_data.map.height / 2 };
        let start_idx = build_data.map.xy_idx(starting_position.x, starting_position.y);
        build_data.map.tiles[start_idx] = TileType::Floor;

        let total_tiles = build_data.map.width * build_data.map.height;
        let desired_floor_tiles = (self.settings.floor_percent * total_tiles as f32) as usize;
        let mut floor_tile_count = build_data.map.tiles.iter().filter(|a| **a == TileType::Floor).count();
        let mut digger_count = 0;
        while floor_tile_count  < desired_floor_tiles {
            let mut did_something = false;
            let mut drunk_x;
            let mut drunk_y;
            match self.settings.spawn_mode {
                DrunkSpawnMode::StartingPoint => {
                    drunk_x = starting_position.x;
                    drunk_y = starting_position.y;
                }
                DrunkSpawnMode::Random => {
                    if digger_count == 0 {
                        drunk_x = starting_position.x;
                        drunk_y = starting_position.y;
                    } else {
                        drunk_x = rng.roll_dice(1, build_data.map.width - 3) + 1;
                        drunk_y = rng.roll_dice(1, build_data.map.height - 3) + 1;
                    }
                }
            }
            let mut drunk_life = self.settings.drunken_lifetime;

            while drunk_life > 0 {
                let drunk_idx = build_data.map.xy_idx(drunk_x, drunk_y);
                if build_data.map.tiles[drunk_idx] == TileType::Wall {
                    did_something = true;
                }
                paint(&mut build_data.map, self.settings.symmetry, self.settings.brush_size, drunk_x, drunk_y);
                build_data.map.tiles[drunk_idx] = TileType::DownStairs;

                let stagger_direction = rng.roll_dice(1, 4);
                match stagger_direction {
                    1 => { if drunk_x > 2 { drunk_x -= 1; } }
                    2 => { if drunk_x < build_data.map.width-2 { drunk_x += 1; } }
                    3 => { if drunk_y > 2 { drunk_y -=1; } }
                    _ => { if drunk_y < build_data.map.height-2 { drunk_y += 1; } }
                }

                drunk_life -= 1;
            }
            if did_something {
                build_data.take_snapshot();
            }

            digger_count += 1;
            for t in build_data.map.tiles.iter_mut() {
                if *t == TileType::DownStairs {
                    *t = TileType::Floor;
                }
            }
            floor_tile_count = build_data.map.tiles.iter().filter(|a| **a == TileType::Floor).count();
        }
    }
}
}

再次，您可以通过调整 random_builder 来测试它：

#![allow(unused)]
fn main() {
let mut builder = BuilderChain::new(new_depth);
builder.start_with(DrunkardsWalkBuilder::fearful_symmetry());
builder.with(AreaStartingPosition::new(XStart::CENTER, YStart::CENTER));
builder.with(CullUnreachable::new());
builder.with(VoronoiSpawning::new());
builder.with(DistantExit::new());
builder
}

您可以 cargo run 并查看它的运行情况。

更新扩散限制聚集

这与之前的类似，因此我们将再次仅提供 dla.rs 的代码：

#![allow(unused)]
fn main() {
use super::{InitialMapBuilder, BuilderMap, TileType, Position, Symmetry, paint};
use rltk::RandomNumberGenerator;

#[derive(PartialEq, Copy, Clone)]
#[allow(dead_code)]
pub enum DLAAlgorithm { WalkInwards, WalkOutwards, CentralAttractor }

pub struct DLABuilder {
    algorithm : DLAAlgorithm,
    brush_size: i32,
    symmetry: Symmetry,
    floor_percent: f32,
}


impl InitialMapBuilder for DLABuilder {
    #[allow(dead_code)]
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap) {
        self.build(rng, build_data);
    }
}

impl DLABuilder {
    #[allow(dead_code)]
    pub fn new() -> Box<DLABuilder> {
        Box::new(DLABuilder{
            algorithm: DLAAlgorithm::WalkInwards,
            brush_size: 2,
            symmetry: Symmetry::None,
            floor_percent: 0.25,
        })
    }

    #[allow(dead_code)]
    pub fn walk_inwards() -> Box<DLABuilder> {
        Box::new(DLABuilder{
            algorithm: DLAAlgorithm::WalkInwards,
            brush_size: 1,
            symmetry: Symmetry::None,
            floor_percent: 0.25,
        })
    }

    #[allow(dead_code)]
    pub fn walk_outwards() -> Box<DLABuilder> {
        Box::new(DLABuilder{
            algorithm: DLAAlgorithm::WalkOutwards,
            brush_size: 2,
            symmetry: Symmetry::None,
            floor_percent: 0.25,
        })
    }

    #[allow(dead_code)]
    pub fn central_attractor() -> Box<DLABuilder> {
        Box::new(DLABuilder{
            algorithm: DLAAlgorithm::CentralAttractor,
            brush_size: 2,
            symmetry: Symmetry::None,
            floor_percent: 0.25,
        })
    }

    #[allow(dead_code)]
    pub fn insectoid() -> Box<DLABuilder> {
        Box::new(DLABuilder{
            algorithm: DLAAlgorithm::CentralAttractor,
            brush_size: 2,
            symmetry: Symmetry::Horizontal,
            floor_percent: 0.25,
        })
    }

    #[allow(clippy::map_entry)]
    fn build(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        // 雕刻起始种子
        let starting_position = Position{ x: build_data.map.width/2, y : build_data.map.height/2 };
        let start_idx = build_data.map.xy_idx(starting_position.x, starting_position.y);
        build_data.take_snapshot();
        build_data.map.tiles[start_idx] = TileType::Floor;
        build_data.map.tiles[start_idx-1] = TileType::Floor;
        build_data.map.tiles[start_idx+1] = TileType::Floor;
        build_data.map.tiles[start_idx-build_data.map.width as usize] = TileType::Floor;
        build_data.map.tiles[start_idx+build_data.map.width as usize] = TileType::Floor;

        // 随机游走者
        let total_tiles = build_data.map.width * build_data.map.height;
        let desired_floor_tiles = (self.floor_percent * total_tiles as f32) as usize;
        let mut floor_tile_count = build_data.map.tiles.iter().filter(|a| **a == TileType::Floor).count();
        while floor_tile_count  < desired_floor_tiles {

            match self.algorithm {
                DLAAlgorithm::WalkInwards => {
                    let mut digger_x = rng.roll_dice(1, build_data.map.width - 3) + 1;
                    let mut digger_y = rng.roll_dice(1, build_data.map.height - 3) + 1;
                    let mut prev_x = digger_x;
                    let mut prev_y = digger_y;
                    let mut digger_idx = build_data.map.xy_idx(digger_x, digger_y);
                    while build_data.map.tiles[digger_idx] == TileType::Wall {
                        prev_x = digger_x;
                        prev_y = digger_y;
                        let stagger_direction = rng.roll_dice(1, 4);
                        match stagger_direction {
                            1 => { if digger_x > 2 { digger_x -= 1; } }
                            2 => { if digger_x < build_data.map.width-2 { digger_x += 1; } }
                            3 => { if digger_y > 2 { digger_y -=1; } }
                            _ => { if digger_y < build_data.map.height-2 { digger_y += 1; } }
                        }
                        digger_idx = build_data.map.xy_idx(digger_x, digger_y);
                    }
                    paint(&mut build_data.map, self.symmetry, self.brush_size, prev_x, prev_y);
                }

                DLAAlgorithm::WalkOutwards => {
                    let mut digger_x = starting_position.x;
                    let mut digger_y = starting_position.y;
                    let mut digger_idx = build_data.map.xy_idx(digger_x, digger_y);
                    while build_data.map.tiles[digger_idx] == TileType::Floor {
                        let stagger_direction = rng.roll_dice(1, 4);
                        match stagger_direction {
                            1 => { if digger_x > 2 { digger_x -= 1; } }
                            2 => { if digger_x < build_data.map.width-2 { digger_x += 1; } }
                            3 => { if digger_y > 2 { digger_y -=1; } }
                            _ => { if digger_y < build_data.map.height-2 { digger_y += 1; } }
                        }
                        digger_idx = build_data.map.xy_idx(digger_x, digger_y);
                    }
                    paint(&mut build_data.map, self.symmetry, self.brush_size, digger_x, digger_y);
                }

                DLAAlgorithm::CentralAttractor => {
                    let mut digger_x = rng.roll_dice(1, build_data.map.width - 3) + 1;
                    let mut digger_y = rng.roll_dice(1, build_data.map.height - 3) + 1;
                    let mut prev_x = digger_x;
                    let mut prev_y = digger_y;
                    let mut digger_idx = build_data.map.xy_idx(digger_x, digger_y);

                    let mut path = rltk::line2d(
                        rltk::LineAlg::Bresenham,
                        rltk::Point::new( digger_x, digger_y ),
                        rltk::Point::new( starting_position.x, starting_position.y )
                    );

                    while build_data.map.tiles[digger_idx] == TileType::Wall && !path.is_empty() {
                        prev_x = digger_x;
                        prev_y = digger_y;
                        digger_x = path[0].x;
                        digger_y = path[0].y;
                        path.remove(0);
                        digger_idx = build_data.map.xy_idx(digger_x, digger_y);
                    }
                    paint(&mut build_data.map, self.symmetry, self.brush_size, prev_x, prev_y);
                }
            }

            build_data.take_snapshot();

            floor_tile_count = build_data.map.tiles.iter().filter(|a| **a == TileType::Floor).count();
        }
    }
}
}

更新迷宫构建器

再次，这是 maze.rs 的代码：

#![allow(unused)]
fn main() {
use super::{Map,  InitialMapBuilder, BuilderMap, TileType};
use rltk::RandomNumberGenerator;

pub struct MazeBuilder {}

impl InitialMapBuilder for MazeBuilder {
    #[allow(dead_code)]
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap) {
        self.build(rng, build_data);
    }
}

impl MazeBuilder {
    #[allow(dead_code)]
    pub fn new() -> Box<MazeBuilder> {
        Box::new(MazeBuilder{})
    }

    #[allow(clippy::map_entry)]
    fn build(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        // 迷宫生成
        let mut maze = Grid::new((build_data.map.width / 2)-2, (build_data.map.height / 2)-2, rng);
        maze.generate_maze(build_data);
    }
}

/* 迷宫代码根据 MIT 许可取自 https://github.com/cyucelen/mazeGenerator/ */

const TOP : usize = 0;
const RIGHT : usize = 1;
const BOTTOM : usize = 2;
const LEFT : usize = 3;

#[derive(Copy, Clone)]
struct Cell {
    row: i32,
    column: i32,
    walls: [bool; 4],
    visited: bool,
}

impl Cell {
    fn new(row: i32, column: i32) -> Cell {
        Cell{
            row,
            column,
            walls: [true, true, true, true],
            visited: false
        }
    }

    fn remove_walls(&mut self, next : &mut Cell) {
        let x = self.column - next.column;
        let y = self.row - next.row;

        if x == 1 {
            self.walls[LEFT] = false;
            next.walls[RIGHT] = false;
        }
        else if x == -1 {
            self.walls[RIGHT] = false;
            next.walls[LEFT] = false;
        }
        else if y == 1 {
            self.walls[TOP] = false;
            next.walls[BOTTOM] = false;
        }
        else if y == -1 {
            self.walls[BOTTOM] = false;
            next.walls[TOP] = false;
        }
    }
}

struct Grid<'a> {
    width: i32,
    height: i32,
    cells: Vec<Cell>,
    backtrace: Vec<usize>,
    current: usize,
    rng : &'a mut RandomNumberGenerator
}

impl<'a> Grid<'a> {
    fn new(width: i32, height:i32, rng: &mut RandomNumberGenerator) -> Grid {
        let mut grid = Grid{
            width,
            height,
            cells: Vec::new(),
            backtrace: Vec::new(),
            current: 0,
            rng
        };

        for row in 0..height {
            for column in 0..width {
                grid.cells.push(Cell::new(row, column));
            }
        }

        grid
    }

    fn calculate_index(&self, row: i32, column: i32) -> i32 {
        if row < 0 || column < 0 || column > self.width-1 || row > self.height-1 {
            -1
        } else {
            column + (row * self.width)
        }
    }

    fn get_available_neighbors(&self) -> Vec<usize> {
        let mut neighbors : Vec<usize> = Vec::new();

        let current_row = self.cells[self.current].row;
        let current_column = self.cells[self.current].column;

        let neighbor_indices : [i32; 4] = [
            self.calculate_index(current_row -1, current_column),
            self.calculate_index(current_row, current_column + 1),
            self.calculate_index(current_row + 1, current_column),
            self.calculate_index(current_row, current_column - 1)
        ];

        for i in neighbor_indices.iter() {
            if *i != -1 && !self.cells[*i as usize].visited {
                neighbors.push(*i as usize);
            }
        }

        neighbors
    }

    fn find_next_cell(&mut self) -> Option<usize> {
        let neighbors = self.get_available_neighbors();
        if !neighbors.is_empty() {
            if neighbors.len() == 1 {
                return Some(neighbors[0]);
            } else {
                return Some(neighbors[(self.rng.roll_dice(1, neighbors.len() as i32)-1) as usize]);
            }
        }
        None
    }

    fn generate_maze(&mut self, build_data : &mut BuilderMap) {
        let mut i = 0;
        loop {
            self.cells[self.current].visited = true;
            let next = self.find_next_cell();

            match next {
                Some(next) => {
                    self.cells[next].visited = true;
                    self.backtrace.push(self.current);
                    //   __lower_part__      __higher_part_
                    //   /            \      /            \
                    // --------cell1------ | cell2-----------
                    let (lower_part, higher_part) =
                        self.cells.split_at_mut(std::cmp::max(self.current, next));
                    let cell1 = &mut lower_part[std::cmp::min(self.current, next)];
                    let cell2 = &mut higher_part[0];
                    cell1.remove_walls(cell2);
                    self.current = next;
                }
                None => {
                    if !self.backtrace.is_empty() {
                        self.current = self.backtrace[0];
                        self.backtrace.remove(0);
                    } else {
                        break;
                    }
                }
            }

            if i % 50 == 0 {
                self.copy_to_map(&mut build_data.map);
                build_data.take_snapshot();
            }
            i += 1;
        }
    }

    fn copy_to_map(&self, map : &mut Map) {
        // 清空地图
        for i in map.tiles.iter_mut() { *i = TileType::Wall; }

        for cell in self.cells.iter() {
            let x = cell.column + 1;
            let y = cell.row + 1;
            let idx = map.xy_idx(x * 2, y * 2);

            map.tiles[idx] = TileType::Floor;
            if !cell.walls[TOP] { map.tiles[idx - map.width as usize] = TileType::Floor }
            if !cell.walls[RIGHT] { map.tiles[idx + 1] = TileType::Floor }
            if !cell.walls[BOTTOM] { map.tiles[idx + map.width as usize] = TileType::Floor }
            if !cell.walls[LEFT] { map.tiles[idx - 1] = TileType::Floor }
        }
    }
}
}

更新 Voronoi 地图

这是 Voronoi 构建器（在 voronoi.rs 中）的更新代码：

#![allow(unused)]
fn main() {
use super::{InitialMapBuilder, BuilderMap, TileType};
use rltk::RandomNumberGenerator;

#[derive(PartialEq, Copy, Clone)]
#[allow(dead_code)]
pub enum DistanceAlgorithm { Pythagoras, Manhattan, Chebyshev }

pub struct VoronoiCellBuilder {
    n_seeds: usize,
    distance_algorithm: DistanceAlgorithm
}


impl InitialMapBuilder for VoronoiCellBuilder {
    #[allow(dead_code)]
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap) {
        self.build(rng, build_data);
    }
}

impl VoronoiCellBuilder {
    #[allow(dead_code)]
    pub fn new() -> Box<VoronoiCellBuilder> {
        Box::new(VoronoiCellBuilder{
            n_seeds: 64,
            distance_algorithm: DistanceAlgorithm::Pythagoras,
        })
    }

    #[allow(dead_code)]
    pub fn pythagoras() -> Box<VoronoiCellBuilder> {
        Box::new(VoronoiCellBuilder{
            n_seeds: 64,
            distance_algorithm: DistanceAlgorithm::Pythagoras,
        })
    }

    #[allow(dead_code)]
    pub fn manhattan() -> Box<VoronoiCellBuilder> {
        Box::new(VoronoiCellBuilder{
            n_seeds: 64,
            distance_algorithm: DistanceAlgorithm::Manhattan,
        })
    }

    #[allow(clippy::map_entry)]
    fn build(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        // 制作 Voronoi 图。我们将以困难的方式做到这一点，以了解这项技术！
        let mut voronoi_seeds : Vec<(usize, rltk::Point)> = Vec::new();

        while voronoi_seeds.len() < self.n_seeds {
            let vx = rng.roll_dice(1, build_data.map.width-1);
            let vy = rng.roll_dice(1, build_data.map.height-1);
            let vidx = build_data.map.xy_idx(vx, vy);
            let candidate = (vidx, rltk::Point::new(vx, vy));
            if !voronoi_seeds.contains(&candidate) {
                voronoi_seeds.push(candidate);
            }
        }

        let mut voronoi_distance = vec![(0, 0.0f32) ; self.n_seeds];
        let mut voronoi_membership : Vec<i32> = vec![0 ; build_data.map.width as usize * build_data.map.height as usize];
        for (i, vid) in voronoi_membership.iter_mut().enumerate() {
            let x = i as i32 % build_data.map.width;
            let y = i as i32 / build_data.map.width;

            for (seed, pos) in voronoi_seeds.iter().enumerate() {
                let distance;
                match self.distance_algorithm {
                    DistanceAlgorithm::Pythagoras => {
                        distance = rltk::DistanceAlg::PythagorasSquared.distance2d(
                            rltk::Point::new(x, y),
                            pos.1
                        );
                    }
                    DistanceAlgorithm::Manhattan => {
                        distance = rltk::DistanceAlg::Manhattan.distance2d(
                            rltk::Point::new(x, y),
                            pos.1
                        );
                    }
                    DistanceAlgorithm::Chebyshev => {
                        distance = rltk::DistanceAlg::Chebyshev.distance2d(
                            rltk::Point::new(x, y),
                            pos.1
                        );
                    }
                }
                voronoi_distance[seed] = (seed, distance);
            }

            voronoi_distance.sort_by(|a,b| a.1.partial_cmp(&b.1).unwrap());

            *vid = voronoi_distance[0].0 as i32;
        }

        for y in 1..build_data.map.height-1 {
            for x in 1..build_data.map.width-1 {
                let mut neighbors = 0;
                let my_idx = build_data.map.xy_idx(x, y);
                let my_seed = voronoi_membership[my_idx];
                if voronoi_membership[build_data.map.xy_idx(x-1, y)] != my_seed { neighbors += 1; }
                if voronoi_membership[build_data.map.xy_idx(x+1, y)] != my_seed { neighbors += 1; }
                if voronoi_membership[build_data.map.xy_idx(x, y-1)] != my_seed { neighbors += 1; }
                if voronoi_membership[build_data.map.xy_idx(x, y+1)] != my_seed { neighbors += 1; }

                if neighbors < 2 {
                    build_data.map.tiles[my_idx] = TileType::Floor;
                }
            }
            build_data.take_snapshot();
        }
    }
}
}

更新波函数坍缩

波函数坍缩是一个略有不同的端口，因为它已经有了“前一个构建器”的概念。现在这个概念已经消失了（链式调用是自动的），因此需要更新更多内容。波函数坍缩是一个元构建器，因此它实现了该 trait，而不是初始地图构建器。总的来说，这些更改使它简单得多！所有更改都在 waveform_collapse/mod.rs 中进行：

#![allow(unused)]
fn main() {
use super::{MetaMapBuilder, BuilderMap, Map, TileType};
use rltk::RandomNumberGenerator;
mod common;
use common::*;
mod constraints;
use constraints::*;
mod solver;
use solver::*;

/// 提供一个使用波函数坍缩算法的地图构建器。
pub struct WaveformCollapseBuilder {}

impl MetaMapBuilder for WaveformCollapseBuilder {
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap)  {
        self.build(rng, build_data);
    }
}

impl WaveformCollapseBuilder {
    /// 波函数坍缩的构造函数。
    #[allow(dead_code)]
    pub fn new() -> Box<WaveformCollapseBuilder> {
        Box::new(WaveformCollapseBuilder{})
    }

    fn build(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        const CHUNK_SIZE :i32 = 8;
        build_data.take_snapshot();

        let patterns = build_patterns(&build_data.map, CHUNK_SIZE, true, true);
        let constraints = patterns_to_constraints(patterns, CHUNK_SIZE);
        self.render_tile_gallery(&constraints, CHUNK_SIZE, build_data);

        build_data.map = Map::new(build_data.map.depth);
        loop {
            let mut solver = Solver::new(constraints.clone(), CHUNK_SIZE, &build_data.map);
            while !solver.iteration(&mut build_data.map, rng) {
                build_data.take_snapshot();
            }
            build_data.take_snapshot();
            if solver.possible { break; } // 如果它遇到了不可能的条件，请重试
        }
        build_data.spawn_list.clear();
    }

    fn render_tile_gallery(&mut self, constraints: &[MapChunk], chunk_size: i32, build_data : &mut BuilderMap) {
        build_data.map = Map::new(0);
        let mut counter = 0;
        let mut x = 1;
        let mut y = 1;
        while counter < constraints.len() {
            render_pattern_to_map(&mut build_data.map, &constraints[counter], chunk_size, x, y);

            x += chunk_size + 1;
            if x + chunk_size > build_data.map.width {
                // 移动到下一行
                x = 1;
                y += chunk_size + 1;

                if y + chunk_size > build_data.map.height {
                    // 移动到下一页
                    build_data.take_snapshot();
                    build_data.map = Map::new(0);

                    x = 1;
                    y = 1;
                }
            }

            counter += 1;
        }
        build_data.take_snapshot();
    }
}
}

您可以使用以下代码进行测试：

#![allow(unused)]
fn main() {
let mut builder = BuilderChain::new(new_depth);
builder.start_with(VoronoiCellBuilder::pythagoras());
builder.with(WaveformCollapseBuilder::new());
builder.with(AreaStartingPosition::new(XStart::CENTER, YStart::CENTER));
builder.with(CullUnreachable::new());
builder.with(VoronoiSpawning::new());
builder.with(DistantExit::new());
builder
}

更新预制件构建器

这是一个有趣的东西。PrefabBuilder 既是 InitialMapBuilder 又是 MetaMapBuilder - 两者之间共享代码。幸运的是，这些 traits 是相同的 - 因此我们可以同时实现它们，并从每个 trait 调用到主 build 函数中！Rust 足够智能，可以根据我们存储的 trait 找出我们正在调用哪个 trait - 因此 PrefabBuilder 可以放置在初始或元地图构建器中。

所有更改都在 prefab_builder/mod.rs 中进行：

#![allow(unused)]
fn main() {
use super::{InitialMapBuilder, MetaMapBuilder, BuilderMap, TileType, Position};
use rltk::RandomNumberGenerator;
pub mod prefab_levels;
pub mod prefab_sections;
pub mod prefab_rooms;
use std::collections::HashSet;

#[derive(PartialEq, Copy, Clone)]
#[allow(dead_code)]
pub enum PrefabMode {
    RexLevel{ template : &'static str },
    Constant{ level : prefab_levels::PrefabLevel },
    Sectional{ section : prefab_sections::PrefabSection },
    RoomVaults
}

#[allow(dead_code)]
pub struct PrefabBuilder {
    mode: PrefabMode
}

impl MetaMapBuilder for PrefabBuilder {
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap)  {
        self.build(rng, build_data);
    }
}

impl InitialMapBuilder for PrefabBuilder {
    #[allow(dead_code)]
    fn build_map(&mut self, rng: &mut rltk::RandomNumberGenerator, build_data : &mut BuilderMap) {
        self.build(rng, build_data);
    }
}

impl PrefabBuilder {
    #[allow(dead_code)]
    pub fn new() -> Box<PrefabBuilder> {
        Box::new(PrefabBuilder{
            mode : PrefabMode::RoomVaults,
        })
    }

    #[allow(dead_code)]
    pub fn rex_level(template : &'static str) -> Box<PrefabBuilder> {
        Box::new(PrefabBuilder{
            mode : PrefabMode::RexLevel{ template },
        })
    }

    #[allow(dead_code)]
    pub fn constant(level : prefab_levels::PrefabLevel) -> Box<PrefabBuilder> {
        Box::new(PrefabBuilder{
            mode : PrefabMode::Constant{ level },
        })
    }

    #[allow(dead_code)]
    pub fn sectional(section : prefab_sections::PrefabSection) -> Box<PrefabBuilder> {
        Box::new(PrefabBuilder{
            mode : PrefabMode::Sectional{ section },
        })
    }

    #[allow(dead_code)]
    pub fn vaults() -> Box<PrefabBuilder> {
        Box::new(PrefabBuilder{
            mode : PrefabMode::RoomVaults,
        })
    }

    fn build(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        match self.mode {
            PrefabMode::RexLevel{template} => self.load_rex_map(&template, build_data),
            PrefabMode::Constant{level} => self.load_ascii_map(&level, build_data),
            PrefabMode::Sectional{section} => self.apply_sectional(&section, rng, build_data),
            PrefabMode::RoomVaults => self.apply_room_vaults(rng, build_data)
        }
        build_data.take_snapshot();
    }

    fn char_to_map(&mut self, ch : char, idx: usize, build_data : &mut BuilderMap) {
        match ch {
            ' ' => build_data.map.tiles[idx] = TileType::Floor,
            '#' => build_data.map.tiles[idx] = TileType::Wall,
            '@' => {
                let x = idx as i32 % build_data.map.width;
                let y = idx as i32 / build_data.map.width;
                build_data.map.tiles[idx] = TileType::Floor;
                build_data.starting_position = Some(Position{ x:x as i32, y:y as i32 });
            }
            '>' => build_data.map.tiles[idx] = TileType::DownStairs,
            'g' => {
                build_data.map.tiles[idx] = TileType::Floor;
                build_data.spawn_list.push((idx, "Goblin".to_string()));
            }
            'o' => {
                build_data.map.tiles[idx] = TileType::Floor;
                build_data.spawn_list.push((idx, "Orc".to_string()));
            }
            '^' => {
                build_data.map.tiles[idx] = TileType::Floor;
                build_data.spawn_list.push((idx, "Bear Trap".to_string()));
            }
            '%' => {
                build_data.map.tiles[idx] = TileType::Floor;
                build_data.spawn_list.push((idx, "Rations".to_string()));
            }
            '!' => {
                build_data.map.tiles[idx] = TileType::Floor;
                build_data.spawn_list.push((idx, "Health Potion".to_string()));
            }
            _ => {
                rltk::console::log(format!("Unknown glyph loading map: {}", (ch as u8) as char));
            }
        }
    }

    #[allow(dead_code)]
    fn load_rex_map(&mut self, path: &str, build_data : &mut BuilderMap) {
        let xp_file = rltk::rex::XpFile::from_resource(path).unwrap();

        for layer in &xp_file.layers {
            for y in 0..layer.height {
                for x in 0..layer.width {
                    let cell = layer.get(x, y).unwrap();
                    if x < build_data.map.width as usize && y < build_data.map.height as usize {
                        let idx = build_data.map.xy_idx(x as i32, y as i32);
                        // 我们正在做一些令人讨厌的类型转换，以便更容易在 match 中键入诸如 '#' 之类的东西
                        self.char_to_map(cell.ch as u8 as char, idx, build_data);
                    }
                }
            }
        }
    }

    fn read_ascii_to_vec(template : &str) -> Vec<char> {
        let mut string_vec : Vec<char> = template.chars().filter(|a| *a != '\r' && *a !='\n').collect();
        for c in string_vec.iter_mut() { if *c as u8 == 160u8 { *c = ' '; } }
        string_vec
    }

    #[allow(dead_code)]
    fn load_ascii_map(&mut self, level: &prefab_levels::PrefabLevel, build_data : &mut BuilderMap) {
        let string_vec = PrefabBuilder::read_ascii_to_vec(level.template);

        let mut i = 0;
        for ty in 0..level.height {
            for tx in 0..level.width {
                if tx < build_data.map.width as usize && ty < build_data.map.height as usize {
                    let idx = build_data.map.xy_idx(tx as i32, ty as i32);
                    if i < string_vec.len() { self.char_to_map(string_vec[i], idx, build_data); }
                }
                i += 1;
            }
        }
    }

    fn apply_previous_iteration<F>(&mut self, mut filter: F, _rng: &mut RandomNumberGenerator, build_data : &mut BuilderMap)
        where F : FnMut(i32, i32) -> bool
    {
        let width = build_data.map.width;
        build_data.spawn_list.retain(|(idx, _name)| {
            let x = *idx as i32 % width;
            let y = *idx as i32 / width;
            filter(x, y)
        });
        build_data.take_snapshot();
    }

    #[allow(dead_code)]
    fn apply_sectional(&mut self, section : &prefab_sections::PrefabSection, rng: &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        use prefab_sections::*;

        let string_vec = PrefabBuilder::read_ascii_to_vec(section.template);

        // 放置新 section
        let chunk_x;
        match section.placement.0 {
            HorizontalPlacement::Left => chunk_x = 0,
            HorizontalPlacement::Center => chunk_x = (build_data.map.width / 2) - (section.width as i32 / 2),
            HorizontalPlacement::Right => chunk_x = (build_data.map.width-1) - section.width as i32
        }

        let chunk_y;
        match section.placement.1 {
            VerticalPlacement::Top => chunk_y = 0,
            VerticalPlacement::Center => chunk_y = (build_data.map.height / 2) - (section.height as i32 / 2),
            VerticalPlacement::Bottom => chunk_y = (build_data.map.height-1) - section.height as i32
        }

        // 构建地图
        self.apply_previous_iteration(|x,y| {
            x < chunk_x || x > (chunk_x + section.width as i32) || y < chunk_y || y > (chunk_y + section.height as i32)
        }, rng, build_data);

        let mut i = 0;
        for ty in 0..section.height {
            for tx in 0..section.width {
                if tx > 0 && tx < build_data.map.width as usize -1 && ty < build_data.map.height as usize -1 && ty > 0 {
                    let idx = build_data.map.xy_idx(tx as i32 + chunk_x, ty as i32 + chunk_y);
                    if i < string_vec.len() { self.char_to_map(string_vec[i], idx, build_data); }
                }
                i += 1;
            }
        }
        build_data.take_snapshot();
    }

    fn apply_room_vaults(&mut self, rng : &mut RandomNumberGenerator, build_data : &mut BuilderMap) {
        use prefab_rooms::*;

        // 应用之前的构建器，并保留它生成的所有实体（目前）
        self.apply_previous_iteration(|_x,_y| true, rng, build_data);

        // 我们想要 vault 吗？
        let vault_roll = rng.roll_dice(1, 6) + build_data.map.depth;
        if vault_roll < 4 { return; }

        // 请注意，这是一个占位符，将被移出此函数
        let master_vault_list = vec![TOTALLY_NOT_A_TRAP, CHECKERBOARD, SILLY_SMILE];

        // 将 vault 列表过滤到适用于当前深度的 vault
        let mut possible_vaults : Vec<&PrefabRoom> = master_vault_list
            .iter()
            .filter(|v| { build_data.map.depth >= v.first_depth && build_data.map.depth <= v.last_depth })
            .collect();

        if possible_vaults.is_empty() { return; } // 如果没有什么可构建的，则退出

        let n_vaults = i32::min(rng.roll_dice(1, 3), possible_vaults.len() as i32);
        let mut used_tiles : HashSet<usize> = HashSet::new();

        for _i in 0..n_vaults {

            let vault_index = if possible_vaults.len() == 1 { 0 } else { (rng.roll_dice(1, possible_vaults.len() as i32)-1) as usize };
            let vault = possible_vaults[vault_index];

            // 我们将创建一个 vault 可能适合的位置列表
            let mut vault_positions : Vec<Position> = Vec::new();

            let mut idx = 0usize;
            loop {
                let x = (idx % build_data.map.width as usize) as i32;
                let y = (idx / build_data.map.width as usize) as i32;

                // 检查我们是否不会溢出地图
                if x > 1
                    && (x+vault.width as i32) < build_data.map.width-2
                    && y > 1
                    && (y+vault.height as i32) < build_data.map.height-2
                {

                    let mut possible = true;
                    for ty in 0..vault.height as i32 {
                        for tx in 0..vault.width as i32 {

                            let idx = build_data.map.xy_idx(tx + x, ty + y);
                            if build_data.map.tiles[idx] != TileType::Floor {
                                possible = false;
                            }
                            if used_tiles.contains(&idx) {
                                possible = false;
                            }
                        }
                    }

                    if possible {
                        vault_positions.push(Position{ x,y });
                        break;
                    }

                }

                idx += 1;
                if idx >= build_data.map.tiles.len()-1 { break; }
            }

            if !vault_positions.is_empty() {
                let pos_idx = if vault_positions.len()==1 { 0 } else { (rng.roll_dice(1, vault_positions.len() as i32)-1) as usize };
                let pos = &vault_positions[pos_idx];

                let chunk_x = pos.x;
                let chunk_y = pos.y;

                let width = build_data.map.width; // 当我们在 `retain` 内部访问 `self` 时，借用检查器真的不喜欢这样
                let height = build_data.map.height; //
                build_data.spawn_list.retain(|e| {
                    let idx = e.0 as i32;
                    let x = idx % width;
                    let y = idx / height;
                    x < chunk_x || x > chunk_x + vault.width as i32 || y < chunk_y || y > chunk_y + vault.height as i32
                });

                let string_vec = PrefabBuilder::read_ascii_to_vec(vault.template);
                let mut i = 0;
                for ty in 0..vault.height {
                    for tx in 0..vault.width {
                        let idx = build_data.map.xy_idx(tx as i32 + chunk_x, ty as i32 + chunk_y);
                        if i < string_vec.len() { self.char_to_map(string_vec[i], idx, build_data); }
                        used_tiles.insert(idx);
                        i += 1;
                    }
                }
                build_data.take_snapshot();

                possible_vaults.remove(vault_index);
            }
        }
    }
}
}

您可以使用 random_builder 中的以下代码测试我们最近的更改（在 map_builders/mod.rs 中）：

#![allow(unused)]
fn main() {
let mut builder = BuilderChain::new(new_depth);
builder.start_with(VoronoiCellBuilder::pythagoras());
builder.with(WaveformCollapseBuilder::new());
builder.with(PrefabBuilder::vaults());
builder.with(AreaStartingPosition::new(XStart::CENTER, YStart::CENTER));
builder.with(CullUnreachable::new());
builder.with(VoronoiSpawning::new());
builder.with(PrefabBuilder::sectional(prefab_builder::prefab_sections::UNDERGROUND_FORT));
builder.with(DistantExit::new());
builder
}

这演示了我们方法的强大之处 - 我们正在从小构建块中组合大量功能。在这个例子中，我们正在：

从使用 VoronoiBuilder 在 Pythagoras 模式下生成的地图开始。
使用 WaveformCollapseBuilder 运行修改地图，这将像拼图游戏一样重新排列地图。
通过 PrefabBuilder（在 Vaults 模式下）修改地图，放置 vaults。
使用 AreaStartingPositions 修改地图，指示我们希望在地图中间附近开始。
修改地图以剔除无法到达的区域。
修改地图以使用 Voronoi 生成方法生成实体。
修改地图以添加地下堡垒，再次使用 PrefabBuilder。
修改地图以在最远的位置添加出口楼梯。

删除 MapBuilder Trait 和 common 中的位

现在我们已经有了构建器机制，我们可以删除一些旧代码了。从 common.rs 中，我们可以删除 remove_unreachable_areas_returning_most_distant 和 generate_voronoi_spawn_regions；我们已经用构建器步骤替换了它们。

我们还可以打开 map_builders/mod.rs 并删除 MapBuilder trait 及其实现：我们现在已经完全替换了它。

随机化

像往常一样，我们希望回到地图生成是随机的状态。我们将把这个过程分解为两个步骤。我们将创建一个新函数 random_initial_builder，该函数掷骰子并选择起始构建器。它还返回一个 bool，指示我们是否选择了提供房间数据的算法。基本函数应该看起来很熟悉，但我们已经摆脱了所有 Box::new 调用 - 构造函数现在为我们创建 boxes：

#![allow(unused)]
fn main() {
fn random_initial_builder(rng: &mut rltk::RandomNumberGenerator) -> (Box<dyn InitialMapBuilder>, bool) {
    let builder = rng.roll_dice(1, 17);
    let result : (Box<dyn InitialMapBuilder>, bool);
    match builder {
        1 => result = (BspDungeonBuilder::new(), true),
        2 => result = (BspInteriorBuilder::new(), true),
        3 => result = (CellularAutomataBuilder::new(), false),
        4 => result = (DrunkardsWalkBuilder::open_area(), false),
        5 => result = (DrunkardsWalkBuilder::open_halls(), false),
        6 => result = (DrunkardsWalkBuilder::winding_passages(), false),
        7 => result = (DrunkardsWalkBuilder::fat_passages(), false),
        8 => result = (DrunkardsWalkBuilder::fearful_symmetry(), false),
        9 => result = (MazeBuilder::new(), false),
        10 => result = (DLABuilder::walk_inwards(), false),
        11 => result = (DLABuilder::walk_outwards(), false),
        12 => result = (DLABuilder::central_attractor(), false),
        13 => result = (DLABuilder::insectoid(), false),
        14 => result = (VoronoiCellBuilder::pythagoras(), false),
        15 => result = (VoronoiCellBuilder::manhattan(), false),
        16 => result = (PrefabBuilder::constant(prefab_builder::prefab_levels::WFC_POPULATED), false),
        _ => result = (SimpleMapBuilder::new(), true)
    }
    result
}
}

这是一个非常简单的函数 - 我们掷骰子，匹配结果表并返回我们选择的构建器和房间信息。现在我们将修改我们的 random_builder 函数以使用它：

#![allow(unused)]
fn main() {
pub fn random_builder(new_depth: i32, rng: &mut rltk::RandomNumberGenerator) -> BuilderChain {
    let mut builder = BuilderChain::new(new_depth);
    let (random_starter, has_rooms) = random_initial_builder(rng);
    builder.start_with(random_starter);
    if has_rooms {
        builder.with(RoomBasedSpawner::new());
        builder.with(RoomBasedStairs::new());
        builder.with(RoomBasedStartingPosition::new());
    } else {
        builder.with(AreaStartingPosition::new(XStart::CENTER, YStart::CENTER));
        builder.with(CullUnreachable::new());
        builder.with(VoronoiSpawning::new());
        builder.with(DistantExit::new());
    }

    if rng.roll_dice(1, 3)==1 {
        builder.with(WaveformCollapseBuilder::new());
    }

    if rng.roll_dice(1, 20)==1 {
        builder.with(PrefabBuilder::sectional(prefab_builder::prefab_sections::UNDERGROUND_FORT));
    }

    builder.with(PrefabBuilder::vaults());

    builder
}
}

这应该看起来很熟悉。此函数：

使用我们刚刚创建的函数选择一个随机房间。
如果构建器提供房间数据，我们将链式调用 RoomBasedSpawner、RoomBasedStairs 和 RoomBasedStartingPositiosn - 房间数据所需的三个重要步骤。
如果构建器不提供房间信息，我们将链式调用 AreaStartingPosition、CullUnreachable、VoronoiSpawning 和 DistantExit - 我们过去在每个构建器内部应用的默认值。
我们掷一个 3 面骰子；如果结果是 1 - 我们应用 WaveformCollapseBuilder 来重新排列地图。
我们掷一个 20 面骰子；如果结果是 1 - 我们应用我们的地下堡垒预制件。
我们将 vault 创建应用于最终地图，从而有机会出现预制房间。

总结

这是一个 巨大的 章节，但我们完成了很多工作：

我们现在有一个一致的构建器接口，用于将任意数量的元地图修饰符链接到我们的构建链。这应该使我们能够构建我们想要的地图。
每个构建器现在都 只做一项任务 - 因此如果您需要修复/调试它们，那么去哪里就更加明显了。
构建器不再负责制作其他构建器 - 因此我们已经剔除了一大堆代码，并将 bug 潜入的机会转移到只有一个（简单的）控制流中。

这为下一章奠定了基础，下一章将研究更多使用过滤器来修改地图的方法。

...

本章的源代码可以在这里找到

使用 Rust 开发肉鸽游戏教程