Chapter 10 placeholder.

Cargo.lock

@@ -196,6 +196,15 @@ dependencies = [
  "specs-derive 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "chapter-10-ranged"
+version = "0.1.0"
+dependencies = [
+ "rltk 0.2.5 (git+https://github.com/thebracket/rltk_rs)",
+ "specs 0.15.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "specs-derive 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "cloudabi"
 version = "0.0.3"

Cargo.toml

@@ -21,5 +21,6 @@ members = [
     "chapter-06-monsters",
     "chapter-07-damage",
     "chapter-08-ui",
-    "chapter-09-items"
+    "chapter-09-items",
+    "chapter-10-ranged"
     ]

book/src/SUMMARY.md

@@ -9,3 +9,4 @@
 - [Chapter 7 - Dealing Damage](./chapter_7.md)
 - [Chapter 8 - User Interface](./chapter_8.md)
 - [Chapter 9 - Items and Inventory](./chapter_9.md)
+- [Chapter 10 - Ranged Scrolls/Targeting](./chapter_10.md)

book/src/chapter_10.md

@@ -0,0 +1,21 @@
+# Ranged Scrolls and Targeting
+
+---
+
+***About this tutorial***
+
+*This tutorial is free and open source, and all code uses the MIT license - so you are free to do with it as you like. My hope is that you will enjoy the tutorial, and make great games!*
+
+*If you enjoy this and would like me to keep writing, please consider supporting [my Patreon](https://www.patreon.com/blackfuture).*
+
+---
+
+
+
+**The source code for this chapter may be found [here](https://github.com/thebracket/rustrogueliketutorial/tree/master/chapter-10-ranged)**
+
+---
+
+Copyright (C) 2019, Herbert Wolverson.
+
+---

chapter-10-ranged/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "chapter-10-ranged"
+version = "0.1.0"
+authors = ["Herbert Wolverson <herberticus@gmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+rltk = { git = "https://github.com/thebracket/rltk_rs" }
+specs = "0.15.0"
+specs-derive = "0.4.0"

chapter-10-ranged/src/components.rs

@@ -0,0 +1,87 @@
+extern crate specs;
+use specs::prelude::*;
+extern crate specs_derive;
+extern crate rltk;
+use rltk::{RGB};
+
+#[derive(Component)]
+pub struct Position {
+    pub x: i32,
+    pub y: i32,
+}
+
+#[derive(Component)]
+pub struct Renderable {
+    pub glyph: u8,
+    pub fg: RGB,
+    pub bg: RGB,
+    pub render_order : i32
+}
+ 
+#[derive(Component, Debug)]
+pub struct Player {}
+
+#[derive(Component)]
+pub struct Viewshed {
+    pub visible_tiles : Vec<rltk::Point>,
+    pub range : i32,
+    pub dirty : bool
+}
+
+#[derive(Component, Debug)]
+pub struct Monster {}
+
+#[derive(Component, Debug)]
+pub struct Name {
+    pub name : String
+}
+
+#[derive(Component, Debug)]
+pub struct BlocksTile {}
+
+#[derive(Component, Debug)]
+pub struct CombatStats {
+    pub max_hp : i32,
+    pub hp : i32,
+    pub defense : i32,
+    pub power : i32
+}
+
+#[derive(Component, Debug)]
+pub struct WantsToMelee {
+    pub target : Entity
+}
+
+#[derive(Component, Debug)]
+pub struct SufferDamage {
+    pub amount : i32
+}
+
+#[derive(Component, Debug)]
+pub struct Item {}
+
+#[derive(Component, Debug)]
+pub struct Potion {
+    pub heal_amount : i32
+}
+
+#[derive(Component, Debug)]
+pub struct InBackpack {
+    pub owner : Entity
+}
+
+#[derive(Component, Debug)]
+pub struct WantsToPickupItem {
+    pub collected_by : Entity,
+    pub item : Entity
+}
+
+#[derive(Component, Debug)]
+pub struct WantsToDrinkPotion {
+    pub potion : Entity
+}
+
+#[derive(Component, Debug)]
+pub struct WantsToDropItem {
+    pub item : Entity
+}

chapter-10-ranged/src/damage_system.rs

@@ -0,0 +1,51 @@
+extern crate specs;
+use specs::prelude::*;
+use super::{CombatStats, SufferDamage, Player, Name, gamelog::GameLog};
+
+pub struct DamageSystem {}
+
+impl<'a> System<'a> for DamageSystem {
+    type SystemData = ( WriteStorage<'a, CombatStats>,
+                        WriteStorage<'a, SufferDamage> );
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (mut stats, mut damage) = data;
+
+        for (mut stats, damage) in (&mut stats, &damage).join() {
+            stats.hp -= damage.amount;
+        }
+
+        damage.clear();
+    }
+}
+
+pub fn delete_the_dead(ecs : &mut World) {
+    let mut dead : Vec<Entity> = Vec::new();
+    // Using a scope to make the borrow checker happy
+    {
+        let combat_stats = ecs.read_storage::<CombatStats>();
+        let players = ecs.read_storage::<Player>();
+        let names = ecs.read_storage::<Name>();
+        let entities = ecs.entities();
+        let mut log = ecs.write_resource::<GameLog>();
+        for (entity, stats) in (&entities, &combat_stats).join() {
+            if stats.hp < 1 { 
+                let player = players.get(entity);
+                match player {
+                    None => {
+                        let victim_name = names.get(entity);
+                        if let Some(victim_name) = victim_name {
+                            log.entries.insert(0, format!("{} is dead", &victim_name.name));
+                        }
+                        dead.push(entity)
+                    }
+                    Some(_) => println!("You are dead")
+                }
+            }
+        }
+    }
+
+    for victim in dead {
+        ecs.delete_entity(victim).expect("Unable to delete");
+    }    
+}

chapter-10-ranged/src/gamelog.rs

@@ -0,0 +1,3 @@
+pub struct GameLog {
+    pub entries : Vec<String>
+}

chapter-10-ranged/src/gui.rs

@@ -0,0 +1,172 @@
+extern crate rltk;
+use rltk::{ RGB, Rltk, Console, Point, VirtualKeyCode };
+extern crate specs;
+use specs::prelude::*;
+use super::{CombatStats, Player, gamelog::GameLog, Map, Name, Position, State, InBackpack};
+
+pub fn draw_ui(ecs: &World, ctx : &mut Rltk) {
+    ctx.draw_box(0, 43, 79, 6, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK));
+
+    let combat_stats = ecs.read_storage::<CombatStats>();
+    let players = ecs.read_storage::<Player>();
+    for (_player, stats) in (&players, &combat_stats).join() {
+        let health = format!(" HP: {} / {} ", stats.hp, stats.max_hp);
+        ctx.print_color(12, 43, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), &health);
+
+        ctx.draw_bar_horizontal(28, 43, 51, stats.hp, stats.max_hp, RGB::named(rltk::RED), RGB::named(rltk::BLACK));
+    }
+
+    let log = ecs.fetch::<GameLog>();
+    let mut y = 44;
+    for s in log.entries.iter() {
+        if y < 49 { ctx.print(2, y, &s.to_string()); }
+        y += 1;
+    }
+
+    // Draw mouse cursor
+    let mouse_pos = ctx.mouse_pos();
+    ctx.set_bg(mouse_pos.0, mouse_pos.1, RGB::named(rltk::MAGENTA));
+    draw_tooltips(ecs, ctx);
+}
+
+fn draw_tooltips(ecs: &World, ctx : &mut Rltk) {
+    let map = ecs.fetch::<Map>();
+    let names = ecs.read_storage::<Name>();
+    let positions = ecs.read_storage::<Position>();
+
+    let mouse_pos = ctx.mouse_pos();
+    if mouse_pos.0 >= map.width || mouse_pos.1 >= map.height { return; }
+    let mut tooltip : Vec<String> = Vec::new();
+    for (name, position) in (&names, &positions).join() {
+        if position.x == mouse_pos.0 && position.y == mouse_pos.1 {
+            tooltip.push(name.name.to_string());
+        }
+    }
+
+    if !tooltip.is_empty() {
+        let mut width :i32 = 0;
+        for s in tooltip.iter() {
+            if width < s.len() as i32 { width = s.len() as i32; }
+        }
+        width += 3;
+
+        if mouse_pos.0 > 40 {
+            let arrow_pos = Point::new(mouse_pos.0 - 2, mouse_pos.1);
+            let left_x = mouse_pos.0 - width;
+            let mut y = mouse_pos.1;
+            for s in tooltip.iter() {
+                ctx.print_color(left_x, y, RGB::named(rltk::WHITE), RGB::named(rltk::GREY), &s.to_string());
+                let padding = (width - s.len() as i32)-1;
+                for i in 0..padding {
+                    ctx.print_color(arrow_pos.x - i, y, RGB::named(rltk::WHITE), RGB::named(rltk::GREY), &" ".to_string());
+                }
+                y += 1;
+            }
+            ctx.print_color(arrow_pos.x, arrow_pos.y, RGB::named(rltk::WHITE), RGB::named(rltk::GREY), &"->".to_string());
+        } else {
+            let arrow_pos = Point::new(mouse_pos.0 + 1, mouse_pos.1);
+            let left_x = mouse_pos.0 +3;
+            let mut y = mouse_pos.1;
+            for s in tooltip.iter() {
+                ctx.print_color(left_x, y, RGB::named(rltk::WHITE), RGB::named(rltk::GREY), &s.to_string());
+                let padding = (width - s.len() as i32)-1;
+                for i in 0..padding {
+                    ctx.print_color(left_x + s.len() as i32 + i, y, RGB::named(rltk::WHITE), RGB::named(rltk::GREY), &" ".to_string());
+                }
+                y += 1;
+            }
+            ctx.print_color(arrow_pos.x, arrow_pos.y, RGB::named(rltk::WHITE), RGB::named(rltk::GREY), &"<-".to_string());
+        }
+    }
+}
+
+#[derive(PartialEq, Copy, Clone)]
+pub enum ItemMenuResult { Cancel, NoResponse, Selected }
+
+pub fn show_inventory(gs : &mut State, ctx : &mut Rltk) -> (ItemMenuResult, Option<Entity>) {
+    let player_entity = gs.ecs.fetch::<Entity>();
+    let names = gs.ecs.read_storage::<Name>();
+    let backpack = gs.ecs.read_storage::<InBackpack>();
+    let entities = gs.ecs.entities();
+
+    let inventory = (&backpack, &names).join().filter(|item| item.0.owner == *player_entity );
+    let count = inventory.count();
+
+    let mut y = (25 - (count / 2)) as i32;
+    ctx.draw_box(15, y-2, 31, (count+3) as i32, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK));
+    ctx.print_color(18, y-2, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), "Inventory");
+    ctx.print_color(18, y+count as i32+1, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), "ESCAPE to cancel");
+
+    let mut equippable : Vec<Entity> = Vec::new();
+    let mut j = 0;
+    for (entity, _pack, name) in (&entities, &backpack, &names).join().filter(|item| item.1.owner == *player_entity ) {
+        ctx.set(17, y, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), rltk::to_cp437('('));
+        ctx.set(18, y, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), 97+j as u8);
+        ctx.set(19, y, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), rltk::to_cp437(')'));
+
+        ctx.print(21, y, &name.name.to_string());
+        equippable.push(entity);
+        y += 1;
+        j += 1;
+    }
+
+    match ctx.key {
+        None => (ItemMenuResult::NoResponse, None),
+        Some(key) => {
+            match key {
+                VirtualKeyCode::Escape => { (ItemMenuResult::Cancel, None) }
+                _ => { 
+                    let selection = rltk::letter_to_option(key);
+                    if selection > -1 && selection < count as i32 {
+                        return (ItemMenuResult::Selected, Some(equippable[selection as usize]));
+                    }  
+                    (ItemMenuResult::NoResponse, None)
+                }
+            }
+        }
+    }
+}
+
+pub fn drop_item_menu(gs : &mut State, ctx : &mut Rltk) -> (ItemMenuResult, Option<Entity>) {
+    let player_entity = gs.ecs.fetch::<Entity>();
+    let names = gs.ecs.read_storage::<Name>();
+    let backpack = gs.ecs.read_storage::<InBackpack>();
+    let entities = gs.ecs.entities();
+
+    let inventory = (&backpack, &names).join().filter(|item| item.0.owner == *player_entity );
+    let count = inventory.count();
+
+    let mut y = (25 - (count / 2)) as i32;
+    ctx.draw_box(15, y-2, 31, (count+3) as i32, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK));
+    ctx.print_color(18, y-2, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), "Drop Which Item?");
+    ctx.print_color(18, y+count as i32+1, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), "ESCAPE to cancel");
+
+    let mut equippable : Vec<Entity> = Vec::new();
+    let mut j = 0;
+    for (entity, _pack, name) in (&entities, &backpack, &names).join().filter(|item| item.1.owner == *player_entity ) {
+        ctx.set(17, y, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), rltk::to_cp437('('));
+        ctx.set(18, y, RGB::named(rltk::YELLOW), RGB::named(rltk::BLACK), 97+j as u8);
+        ctx.set(19, y, RGB::named(rltk::WHITE), RGB::named(rltk::BLACK), rltk::to_cp437(')'));
+
+        ctx.print(21, y, &name.name.to_string());
+        equippable.push(entity);
+        y += 1;
+        j += 1;
+    }
+
+    match ctx.key {
+        None => (ItemMenuResult::NoResponse, None),
+        Some(key) => {
+            match key {
+                VirtualKeyCode::Escape => { (ItemMenuResult::Cancel, None) }
+                _ => { 
+                    let selection = rltk::letter_to_option(key);
+                    if selection > -1 && selection < count as i32 {
+                        return (ItemMenuResult::Selected, Some(equippable[selection as usize]));
+                    }  
+                    (ItemMenuResult::NoResponse, None)
+                }
+            }
+        }
+    }
+}

chapter-10-ranged/src/inventory_system.rs

@@ -0,0 +1,101 @@
+extern crate specs;
+use specs::prelude::*;
+use super::{WantsToPickupItem, Name, InBackpack, Position, gamelog::GameLog, WantsToDrinkPotion, 
+    Potion, CombatStats, WantsToDropItem};
+
+pub struct ItemCollectionSystem {}
+
+impl<'a> System<'a> for ItemCollectionSystem {
+    #[allow(clippy::type_complexity)]
+    type SystemData = ( ReadExpect<'a, Entity>,
+                        WriteExpect<'a, GameLog>,
+                        WriteStorage<'a, WantsToPickupItem>,
+                        WriteStorage<'a, Position>,
+                        ReadStorage<'a, Name>,
+                        WriteStorage<'a, InBackpack>
+                      );
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (player_entity, mut gamelog, mut wants_pickup, mut positions, names, mut backpack) = data;
+
+        for pickup in wants_pickup.join() {
+            positions.remove(pickup.item);
+            backpack.insert(pickup.item, InBackpack{ owner: pickup.collected_by }).expect("Unable to insert backpack entry");
+
+            if pickup.collected_by == *player_entity {
+                gamelog.entries.insert(0, format!("You pick up the {}.", names.get(pickup.item).unwrap().name));
+            }
+        }
+
+        wants_pickup.clear();
+    }
+}
+
+pub struct PotionUseSystem {}
+
+impl<'a> System<'a> for PotionUseSystem {
+    #[allow(clippy::type_complexity)]
+    type SystemData = ( ReadExpect<'a, Entity>,
+                        WriteExpect<'a, GameLog>,
+                        Entities<'a>,
+                        WriteStorage<'a, WantsToDrinkPotion>,
+                        ReadStorage<'a, Name>,
+                        ReadStorage<'a, Potion>,
+                        WriteStorage<'a, CombatStats>
+                      );
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (player_entity, mut gamelog, entities, mut wants_drink, names, potions, mut combat_stats) = data;
+
+        for (entity, drink, stats) in (&entities, &wants_drink, &mut combat_stats).join() {
+            let potion = potions.get(drink.potion);
+            match potion {
+                None => {}
+                Some(potion) => {
+                    stats.hp = i32::max(stats.max_hp, stats.hp + potion.heal_amount);
+                    if entity == *player_entity {
+                        gamelog.entries.insert(0, format!("You drink the {}, healing {} hp.", names.get(drink.potion).unwrap().name, potion.heal_amount));
+                    }
+                    entities.delete(drink.potion).expect("Delete failed");
+                }
+            }
+        }
+
+        wants_drink.clear();
+    }
+}
+
+pub struct ItemDropSystem {}
+
+impl<'a> System<'a> for ItemDropSystem {
+    #[allow(clippy::type_complexity)]
+    type SystemData = ( ReadExpect<'a, Entity>,
+                        WriteExpect<'a, GameLog>,
+                        Entities<'a>,
+                        WriteStorage<'a, WantsToDropItem>,
+                        ReadStorage<'a, Name>,
+                        WriteStorage<'a, Position>,
+                        WriteStorage<'a, InBackpack>
+                      );
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (player_entity, mut gamelog, entities, mut wants_drop, names, mut positions, mut backpack) = data;
+
+        for (entity, to_drop) in (&entities, &wants_drop).join() {
+            let mut dropper_pos : Position = Position{x:0, y:0};
+            {
+                let dropped_pos = positions.get(entity).unwrap();
+                dropper_pos.x = dropped_pos.x;
+                dropper_pos.y = dropped_pos.y;
+            }
+            positions.insert(to_drop.item, Position{ x : dropper_pos.x, y : dropper_pos.y }).expect("Unable to insert position");
+            backpack.remove(to_drop.item);
+
+            if entity == *player_entity {
+                gamelog.entries.insert(0, format!("You drop up the {}.", names.get(to_drop.item).unwrap().name));
+            }
+        }
+
+        wants_drop.clear();
+    }
+}

chapter-10-ranged/src/main.rs

@@ -0,0 +1,171 @@
+extern crate rltk;
+use rltk::{Console, GameState, Rltk, Point};
+extern crate specs;
+use specs::prelude::*;
+#[macro_use]
+extern crate specs_derive;
+mod components;
+pub use components::*;
+mod map;
+pub use map::*;
+mod player;
+use player::*;
+mod rect;
+pub use rect::Rect;
+mod visibility_system;
+use visibility_system::VisibilitySystem;
+mod monster_ai_system;
+use monster_ai_system::MonsterAI;
+mod map_indexing_system;
+use map_indexing_system::MapIndexingSystem;
+mod melee_combat_system;
+use melee_combat_system::MeleeCombatSystem;
+mod damage_system;
+use damage_system::DamageSystem;
+mod gui;
+mod gamelog;
+mod spawner;
+mod inventory_system;
+use inventory_system::{ ItemCollectionSystem, PotionUseSystem, ItemDropSystem };
+
+#[derive(PartialEq, Copy, Clone)]
+pub enum RunState { AwaitingInput, PreRun, PlayerTurn, MonsterTurn, ShowInventory, ShowDropItem }
+
+pub struct State {
+    pub ecs: World,
+    pub systems: Dispatcher<'static, 'static>
+}
+
+impl GameState for State {
+    fn tick(&mut self, ctx : &mut Rltk) {
+        ctx.cls();        
+
+        draw_map(&self.ecs, ctx);
+
+        {
+            let positions = self.ecs.read_storage::<Position>();
+            let renderables = self.ecs.read_storage::<Renderable>();
+            let map = self.ecs.fetch::<Map>();
+
+            let mut data = (&positions, &renderables).join().collect::<Vec<_>>();
+            data.sort_by(|&a, &b| b.1.render_order.cmp(&a.1.render_order) );
+            for (pos, render) in data.iter() {
+                let idx = map.xy_idx(pos.x, pos.y);
+                if map.visible_tiles[idx] { ctx.set(pos.x, pos.y, render.fg, render.bg, render.glyph) }
+            }
+
+            gui::draw_ui(&self.ecs, ctx);
+        }
+
+        let mut newrunstate;
+        {
+            let runstate = self.ecs.fetch::<RunState>();
+            newrunstate = *runstate;
+        }
+        
+        match newrunstate {
+            RunState::PreRun => {
+                self.systems.dispatch(&self.ecs);
+                self.ecs.maintain();
+                newrunstate = RunState::AwaitingInput;
+            }
+            RunState::AwaitingInput => {
+                newrunstate = player_input(self, ctx);
+            }
+            RunState::PlayerTurn => {
+                self.systems.dispatch(&self.ecs);
+                self.ecs.maintain();
+                newrunstate = RunState::MonsterTurn;
+            }
+            RunState::MonsterTurn => {
+                self.systems.dispatch(&self.ecs);
+                self.ecs.maintain();
+                newrunstate = RunState::AwaitingInput;
+            }
+            RunState::ShowInventory => {
+                let result = gui::show_inventory(self, ctx);
+                match result.0 {
+                    gui::ItemMenuResult::Cancel => newrunstate = RunState::AwaitingInput,
+                    gui::ItemMenuResult::NoResponse => {}
+                    gui::ItemMenuResult::Selected => {
+                        let item_entity = result.1.unwrap();
+                        let mut intent = self.ecs.write_storage::<WantsToDrinkPotion>();
+                        intent.insert(*self.ecs.fetch::<Entity>(), WantsToDrinkPotion{ potion: item_entity }).expect("Unable to insert intent");
+                        newrunstate = RunState::PlayerTurn;
+                    }
+                }
+            }
+            RunState::ShowDropItem => {
+                let result = gui::drop_item_menu(self, ctx);
+                match result.0 {
+                    gui::ItemMenuResult::Cancel => newrunstate = RunState::AwaitingInput,
+                    gui::ItemMenuResult::NoResponse => {}
+                    gui::ItemMenuResult::Selected => {
+                        let item_entity = result.1.unwrap();
+                        let mut intent = self.ecs.write_storage::<WantsToDropItem>();
+                        intent.insert(*self.ecs.fetch::<Entity>(), WantsToDropItem{ item: item_entity }).expect("Unable to insert intent");
+                        newrunstate = RunState::PlayerTurn;
+                    }
+                }
+            }
+        }
+
+        {
+            let mut runwriter = self.ecs.write_resource::<RunState>();
+            *runwriter = newrunstate;
+        }
+        damage_system::delete_the_dead(&mut self.ecs);
+    }
+}
+
+fn main() {
+    let mut context = Rltk::init_simple8x8(80, 50, "Hello Rust World", "../resources");
+    context.with_post_scanlines(true);
+    let mut gs = State {
+        ecs: World::new(),
+        systems : DispatcherBuilder::new()
+            .with(MapIndexingSystem{}, "map_indexing_system", &[])
+            .with(VisibilitySystem{}, "visibility_system", &[])
+            .with(MonsterAI{}, "monster_ai", &["visibility_system", "map_indexing_system"])
+            .with(MeleeCombatSystem{}, "melee_combat", &["monster_ai"])
+            .with(DamageSystem{}, "damage", &["melee_combat"])
+            .with(ItemCollectionSystem{}, "pickup", &["melee_combat"])
+            .with(PotionUseSystem{}, "potions", &["melee_combat"])
+            .with(ItemDropSystem{}, "drop_items", &["melee_combat"])
+            .build(),
+    };
+    gs.ecs.register::<Position>();
+    gs.ecs.register::<Renderable>();
+    gs.ecs.register::<Player>();
+    gs.ecs.register::<Viewshed>();
+    gs.ecs.register::<Monster>();
+    gs.ecs.register::<Name>();
+    gs.ecs.register::<BlocksTile>();
+    gs.ecs.register::<CombatStats>();
+    gs.ecs.register::<WantsToMelee>();
+    gs.ecs.register::<SufferDamage>();
+    gs.ecs.register::<Item>();
+    gs.ecs.register::<Potion>();
+    gs.ecs.register::<InBackpack>();
+    gs.ecs.register::<WantsToPickupItem>();
+    gs.ecs.register::<WantsToDrinkPotion>();
+    gs.ecs.register::<WantsToDropItem>();
+
+    let map : Map = Map::new_map_rooms_and_corridors();
+    let (player_x, player_y) = map.rooms[0].center();
+
+    let player_entity = spawner::player(&mut gs.ecs, player_x, player_y);
+
+    gs.ecs.insert(rltk::RandomNumberGenerator::new());
+    for room in map.rooms.iter().skip(1) {
+        spawner::spawn_room(&mut gs.ecs, room);
+    }
+
+    gs.ecs.insert(map);
+    gs.ecs.insert(Point::new(player_x, player_y));
+    gs.ecs.insert(player_entity);
+    gs.ecs.insert(RunState::PreRun);
+    gs.ecs.insert(gamelog::GameLog{ entries : vec!["Welcome to Rusty Roguelike".to_string()] });
+
+    rltk::main_loop(context, gs);
+}

chapter-10-ranged/src/map.rs

@@ -0,0 +1,206 @@
+extern crate rltk;
+use rltk::{ RGB, Rltk, Console, RandomNumberGenerator, BaseMap, Algorithm2D, Point };
+use super::{Rect};
+use std::cmp::{max, min};
+extern crate specs;
+use specs::prelude::*;
+
+pub const MAPWIDTH : usize = 80;
+pub const MAPHEIGHT : usize = 43;
+pub const MAPCOUNT : usize = MAPHEIGHT * MAPWIDTH;
+
+#[derive(PartialEq, Copy, Clone)]
+pub enum TileType {
+    Wall, Floor
+}
+
+#[derive(Default)]
+pub struct Map {
+    pub tiles : Vec<TileType>,
+    pub rooms : Vec<Rect>,
+    pub width : i32,
+    pub height : i32,
+    pub revealed_tiles : Vec<bool>,
+    pub visible_tiles : Vec<bool>,
+    pub blocked : Vec<bool>,
+    pub tile_content : Vec<Vec<Entity>>
+}
+
+impl Map {
+    pub fn xy_idx(&self, x: i32, y: i32) -> usize {
+        (y as usize * self.width as usize) + x as usize
+    }
+
+    fn apply_room_to_map(&mut self, room : &Rect) {
+        for y in room.y1 +1 ..= room.y2 {
+            for x in room.x1 + 1 ..= room.x2 {
+                let idx = self.xy_idx(x, y);
+                self.tiles[idx] = TileType::Floor;
+            }
+        }
+    }
+
+    fn apply_horizontal_tunnel(&mut self, x1:i32, x2:i32, y:i32) {
+        for x in min(x1,x2) ..= max(x1,x2) {
+            let idx = self.xy_idx(x, y);
+            if idx > 0 && idx < self.width as usize * self.height as usize {
+                self.tiles[idx as usize] = TileType::Floor;
+            }
+        }
+    }
+
+    fn apply_vertical_tunnel(&mut self, y1:i32, y2:i32, x:i32) {
+        for y in min(y1,y2) ..= max(y1,y2) {
+            let idx = self.xy_idx(x, y);
+            if idx > 0 && idx < self.width as usize * self.height as usize {
+                self.tiles[idx as usize] = TileType::Floor;
+            }
+        }
+    }
+
+    fn is_exit_valid(&self, x:i32, y:i32) -> bool {
+        if x < 1 || x > self.width-1 || y < 1 || y > self.height-1 { return false; }
+        let idx = (y * self.width) + x;
+        !self.blocked[idx as usize]
+    }
+
+    pub fn populate_blocked(&mut self) {        
+        for (i,tile) in self.tiles.iter_mut().enumerate() {
+            self.blocked[i] = *tile == TileType::Wall;
+        }
+    }
+
+    pub fn clear_content_index(&mut self) {
+        for content in self.tile_content.iter_mut() {
+            content.clear();
+        }
+    }
+
+    /// Makes a new map using the algorithm from http://rogueliketutorials.com/tutorials/tcod/part-3/
+    /// This gives a handful of random rooms and corridors joining them together.
+    pub fn new_map_rooms_and_corridors() -> Map {
+        let mut map = Map{
+            tiles : vec![TileType::Wall; MAPCOUNT],
+            rooms : Vec::new(),
+            width : MAPWIDTH as i32,
+            height: MAPHEIGHT as i32,
+            revealed_tiles : vec![false; MAPCOUNT],
+            visible_tiles : vec![false; MAPCOUNT],
+            blocked : vec![false; MAPCOUNT],
+            tile_content : vec![Vec::new(); MAPCOUNT]
+        };
+
+        const MAX_ROOMS : i32 = 30;
+        const MIN_SIZE : i32 = 6;
+        const MAX_SIZE : i32 = 10;
+
+        let mut rng = RandomNumberGenerator::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, map.width - w - 1) - 1;
+            let y = rng.roll_dice(1, map.height - h - 1) - 1;
+            let new_room = Rect::new(x, y, w, h);
+            let mut ok = true;
+            for other_room in map.rooms.iter() {
+                if new_room.intersect(other_room) { ok = false }
+            }
+            if ok {
+                map.apply_room_to_map(&new_room);
+
+                if !map.rooms.is_empty() {
+                    let (new_x, new_y) = new_room.center();
+                    let (prev_x, prev_y) = map.rooms[map.rooms.len()-1].center();
+                    if rng.range(0,1) == 1 {
+                        map.apply_horizontal_tunnel(prev_x, new_x, prev_y);
+                        map.apply_vertical_tunnel(prev_y, new_y, new_x);
+                    } else {
+                        map.apply_vertical_tunnel(prev_y, new_y, prev_x);
+                        map.apply_horizontal_tunnel(prev_x, new_x, new_y);
+                    }
+                }
+
+                map.rooms.push(new_room);
+            }
+        }
+
+        map
+    }
+}
+
+impl BaseMap for Map {
+    fn is_opaque(&self, idx:i32) -> bool {
+        self.tiles[idx as usize] == TileType::Wall
+    }
+
+    fn get_available_exits(&self, idx:i32) -> Vec<(i32, f32)> {
+        let mut exits : Vec<(i32, f32)> = Vec::new();
+        let x = idx % self.width;
+        let y = idx / self.width;
+
+        // Cardinal directions
+        if self.is_exit_valid(x-1, y) { exits.push((idx-1, 1.0)) };
+        if self.is_exit_valid(x+1, y) { exits.push((idx+1, 1.0)) };
+        if self.is_exit_valid(x, y-1) { exits.push((idx-self.width, 1.0)) };
+        if self.is_exit_valid(x, y+1) { exits.push((idx+self.width, 1.0)) };
+
+        // Diagonals
+        if self.is_exit_valid(x-1, y-1) { exits.push(((idx-self.width)-1, 1.45)); }
+        if self.is_exit_valid(x+1, y-1) { exits.push(((idx-self.width)+1, 1.45)); }
+        if self.is_exit_valid(x-1, y+1) { exits.push(((idx+self.width)-1, 1.45)); }
+        if self.is_exit_valid(x+1, y+1) { exits.push(((idx+self.width)+1, 1.45)); }
+
+        exits
+    }
+
+    fn get_pathing_distance(&self, idx1:i32, idx2:i32) -> f32 {
+        let p1 = Point::new(idx1 % self.width, idx1 / self.width);
+        let p2 = Point::new(idx2 % self.width, idx2 / self.width);
+        rltk::DistanceAlg::Pythagoras.distance2d(p1, p2)
+    }
+}
+
+impl Algorithm2D for Map {
+    fn point2d_to_index(&self, pt: Point) -> i32 {
+        (pt.y * self.width) + pt.x
+    }
+
+    fn index_to_point2d(&self, idx:i32) -> Point {
+        Point{ x: idx % self.width, y: idx / self.width }
+    }
+}
+
+pub fn draw_map(ecs: &World, ctx : &mut Rltk) {
+    let map = ecs.fetch::<Map>();
+
+    let mut y = 0;
+    let mut x = 0;
+    for (idx,tile) in map.tiles.iter().enumerate() {
+        // Render a tile depending upon the tile type
+
+        if map.revealed_tiles[idx] {
+            let glyph;
+            let mut fg;
+            match tile {
+                TileType::Floor => {
+                    glyph = rltk::to_cp437('.');
+                    fg = RGB::from_f32(0.0, 0.5, 0.5);
+                }
+                TileType::Wall => {
+                    glyph = rltk::to_cp437('#');
+                    fg = RGB::from_f32(0., 1.0, 0.);
+                }
+            }
+            if !map.visible_tiles[idx] { fg = fg.to_greyscale() }
+            ctx.set(x, y, fg, RGB::from_f32(0., 0., 0.), glyph);
+        }
+
+        // Move the coordinates
+        x += 1;
+        if x > MAPWIDTH as i32-1 {
+            x = 0;
+            y += 1;
+        }
+    }
+}

chapter-10-ranged/src/map_indexing_system.rs

@@ -0,0 +1,32 @@
+extern crate specs;
+use specs::prelude::*;
+use super::{Map, Position, BlocksTile};
+
+pub struct MapIndexingSystem {}
+
+impl<'a> System<'a> for MapIndexingSystem {
+    type SystemData = ( WriteExpect<'a, Map>,
+                        ReadStorage<'a, Position>,
+                        ReadStorage<'a, BlocksTile>,
+                        Entities<'a>,);
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (mut map, position, blockers, entities) = data;
+
+        map.populate_blocked();
+        map.clear_content_index();
+        for (entity, position) in (&entities, &position).join() {
+            let idx = map.xy_idx(position.x, position.y);
+
+            // If they block, update the blocking list
+            let _p : Option<&BlocksTile> = blockers.get(entity);
+            if let Some(_p) = _p {
+                map.blocked[idx] = true;
+            }
+            
+            // Push the entity to the appropriate index slot. It's a Copy
+            // type, so we don't need to clone it (we want to avoid moving it out of the ECS!)
+            map.tile_content[idx].push(entity);
+        }
+    }
+}

chapter-10-ranged/src/melee_combat_system.rs

@@ -0,0 +1,40 @@
+extern crate specs;
+use specs::prelude::*;
+use super::{CombatStats, WantsToMelee, Name, SufferDamage, gamelog::GameLog};
+
+pub struct MeleeCombatSystem {}
+
+impl<'a> System<'a> for MeleeCombatSystem {
+    #[allow(clippy::type_complexity)]
+    type SystemData = ( Entities<'a>,
+                        WriteExpect<'a, GameLog>,
+                        WriteStorage<'a, WantsToMelee>,
+                        ReadStorage<'a, Name>,
+                        ReadStorage<'a, CombatStats>,
+                        WriteStorage<'a, SufferDamage>
+                      );
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (entities, mut log, mut wants_melee, names, combat_stats, mut inflict_damage) = data;
+
+        for (_entity, wants_melee, name, stats) in (&entities, &wants_melee, &names, &combat_stats).join() {
+            if stats.hp > 0 {
+                let target_stats = combat_stats.get(wants_melee.target).unwrap();
+                if target_stats.hp > 0 {
+                    let target_name = names.get(wants_melee.target).unwrap();
+
+                    let damage = i32::max(0, stats.power - target_stats.defense);
+
+                    if damage == 0 {
+                        log.entries.insert(0, format!("{} is unable to hurt {}", &name.name, &target_name.name));
+                    } else {
+                        log.entries.insert(0, format!("{} hits {}, for {} hp.", &name.name, &target_name.name, damage));
+                        inflict_damage.insert(wants_melee.target, SufferDamage{ amount: damage }).expect("Unable to do damage");                        
+                    }
+                }
+            }
+        }
+
+        wants_melee.clear();
+    }
+}

chapter-10-ranged/src/monster_ai_system.rs

@@ -0,0 +1,50 @@
+extern crate specs;
+use specs::prelude::*;
+use super::{Viewshed, Monster, Map, Position, WantsToMelee, RunState};
+extern crate rltk;
+use rltk::{Point};
+
+pub struct MonsterAI {}
+
+impl<'a> System<'a> for MonsterAI {
+    #[allow(clippy::type_complexity)]
+    type SystemData = ( WriteExpect<'a, Map>,
+                        ReadExpect<'a, Point>,
+                        ReadExpect<'a, Entity>,
+                        ReadExpect<'a, RunState>,
+                        Entities<'a>,
+                        WriteStorage<'a, Viewshed>, 
+                        ReadStorage<'a, Monster>,
+                        WriteStorage<'a, Position>,
+                        WriteStorage<'a, WantsToMelee>);
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (mut map, player_pos, player_entity, runstate, entities, mut viewshed, monster, mut position, mut wants_to_melee) = data;
+
+        if *runstate != RunState::MonsterTurn { return; }
+
+        for (entity, mut viewshed,_monster,mut pos) in (&entities, &mut viewshed, &monster, &mut position).join() {
+            let distance = rltk::DistanceAlg::Pythagoras.distance2d(Point::new(pos.x, pos.y), *player_pos);
+            if distance < 1.5 {
+                wants_to_melee.insert(entity, WantsToMelee{ target: *player_entity }).expect("Unable to insert attack");
+            }
+            else if viewshed.visible_tiles.contains(&*player_pos) {
+                // Path to the player
+                let path = rltk::a_star_search(
+                    map.xy_idx(pos.x, pos.y) as i32, 
+                    map.xy_idx(player_pos.x, player_pos.y) as i32, 
+                    &mut *map
+                );
+                if path.success && path.steps.len()>1 {
+                    let mut idx = map.xy_idx(pos.x, pos.y);
+                    map.blocked[idx] = false;
+                    pos.x = path.steps[1] % map.width;
+                    pos.y = path.steps[1] / map.width;
+                    idx = map.xy_idx(pos.x, pos.y);
+                    map.blocked[idx] = true;
+                    viewshed.dirty = true;
+                }
+            }
+        }
+    }
+}

chapter-10-ranged/src/player.rs

@@ -0,0 +1,112 @@
+extern crate rltk;
+use rltk::{VirtualKeyCode, Rltk, Point};
+extern crate specs;
+use specs::prelude::*;
+use super::{Position, Player, Viewshed, State, Map, RunState, CombatStats, WantsToMelee, Item,
+    gamelog::GameLog, WantsToPickupItem};
+
+pub fn try_move_player(delta_x: i32, delta_y: i32, ecs: &mut World) {
+    let mut positions = ecs.write_storage::<Position>();
+    let players = ecs.read_storage::<Player>();
+    let mut viewsheds = ecs.write_storage::<Viewshed>();
+    let entities = ecs.entities();
+    let combat_stats = ecs.read_storage::<CombatStats>();
+    let map = ecs.fetch::<Map>();
+    let mut wants_to_melee = ecs.write_storage::<WantsToMelee>();
+
+    for (entity, _player, pos, viewshed) in (&entities, &players, &mut positions, &mut viewsheds).join() {
+        let destination_idx = map.xy_idx(pos.x + delta_x, pos.y + delta_y);
+
+        for potential_target in map.tile_content[destination_idx].iter() {
+            let target = combat_stats.get(*potential_target);
+            if let Some(_target) = target {
+                wants_to_melee.insert(entity, WantsToMelee{ target: *potential_target }).expect("Add target failed");
+                return;
+            }
+        }
+
+        if !map.blocked[destination_idx] {
+            pos.x += delta_x;
+            pos.y += delta_y;
+
+            if pos.x < 0 { pos.x = 0; }
+            if pos.x > 79 { pos.y = 79; }
+            if pos.y < 0 { pos.y = 0; }
+            if pos.y > 49 { pos.y = 49; }
+
+            viewshed.dirty = true;
+            let mut ppos = ecs.write_resource::<Point>();
+            ppos.x = pos.x;
+            ppos.y = pos.y;
+        }
+    }
+}
+
+fn get_item(ecs: &mut World) {
+    let player_pos = ecs.fetch::<Point>();
+    let player_entity = ecs.fetch::<Entity>();
+    let entities = ecs.entities();
+    let items = ecs.read_storage::<Item>();
+    let positions = ecs.read_storage::<Position>();
+    let mut gamelog = ecs.fetch_mut::<GameLog>();    
+
+    let mut target_item : Option<Entity> = None;
+    for (item_entity, _item, position) in (&entities, &items, &positions).join() {
+        if position.x == player_pos.x && position.y == player_pos.y {
+            target_item = Some(item_entity);
+        }
+    }
+
+    match target_item {
+        None => gamelog.entries.insert(0, "There is nothing here to pick up.".to_string()),
+        Some(item) => {
+            let mut pickup = ecs.write_storage::<WantsToPickupItem>();
+            pickup.insert(*player_entity, WantsToPickupItem{ collected_by: *player_entity, item }).expect("Unable to insert want to pickup");
+        }
+    }
+}
+
+pub fn player_input(gs: &mut State, ctx: &mut Rltk) -> RunState {
+    // Player movement
+    match ctx.key {
+        None => { return RunState::AwaitingInput } // Nothing happened
+        Some(key) => match key {
+            VirtualKeyCode::Left => try_move_player(-1, 0, &mut gs.ecs),
+            VirtualKeyCode::Numpad4 => try_move_player(-1, 0, &mut gs.ecs),
+            VirtualKeyCode::H => try_move_player(-1, 0, &mut gs.ecs),
+
+            VirtualKeyCode::Right => try_move_player(1, 0, &mut gs.ecs),
+            VirtualKeyCode::Numpad6 => try_move_player(1, 0, &mut gs.ecs),            
+            VirtualKeyCode::L => try_move_player(1, 0, &mut gs.ecs),
+
+            VirtualKeyCode::Up => try_move_player(0, -1, &mut gs.ecs),
+            VirtualKeyCode::Numpad8 => try_move_player(0, -1, &mut gs.ecs),
+            VirtualKeyCode::K => try_move_player(0, -1, &mut gs.ecs),
+
+            VirtualKeyCode::Down => try_move_player(0, 1, &mut gs.ecs),
+            VirtualKeyCode::Numpad2 => try_move_player(0, 1, &mut gs.ecs),
+            VirtualKeyCode::J => try_move_player(0, 1, &mut gs.ecs),
+
+            // Diagonals
+            VirtualKeyCode::Numpad9 => try_move_player(1, -1, &mut gs.ecs),
+            VirtualKeyCode::Y => try_move_player(1, -1, &mut gs.ecs),
+
+            VirtualKeyCode::Numpad7 => try_move_player(-1, -1, &mut gs.ecs),
+            VirtualKeyCode::U => try_move_player(-1, -1, &mut gs.ecs),
+
+            VirtualKeyCode::Numpad3 => try_move_player(1, 1, &mut gs.ecs),
+            VirtualKeyCode::N => try_move_player(1, 1, &mut gs.ecs),
+
+            VirtualKeyCode::Numpad1 => try_move_player(-1, 1, &mut gs.ecs),
+            VirtualKeyCode::B => try_move_player(-1, 1, &mut gs.ecs),
+
+            // Picking up items
+            VirtualKeyCode::G => get_item(&mut gs.ecs),
+            VirtualKeyCode::I => return RunState::ShowInventory,
+            VirtualKeyCode::D => return RunState::ShowDropItem,
+
+            _ => { return RunState::AwaitingInput }
+        },
+    }
+    RunState::PlayerTurn
+}

chapter-10-ranged/src/rect.rs

@@ -0,0 +1,21 @@
+pub struct Rect {
+    pub x1 : i32,
+    pub x2 : i32,
+    pub y1 : i32,
+    pub y2 : i32
+}
+
+impl Rect {
+    pub fn new(x:i32, y: i32, w:i32, h:i32) -> Rect {
+        Rect{x1:x, y1:y, x2:x+w, y2:y+h}
+    }
+
+    // Returns true if this overlaps with other
+    pub fn intersect(&self, other:&Rect) -> bool {
+        self.x1 <= other.x2 && self.x2 >= other.x1 && self.y1 <= other.y2 && self.y2 >= other.y1
+    }
+
+    pub fn center(&self) -> (i32, i32) {
+        ((self.x1 + self.x2)/2, (self.y1 + self.y2)/2)
+    }
+}

chapter-10-ranged/src/spawner.rs

@@ -0,0 +1,126 @@
+extern crate rltk;
+use rltk::{ RGB, RandomNumberGenerator };
+extern crate specs;
+use specs::prelude::*;
+use super::{CombatStats, Player, Renderable, Name, Position, Viewshed, Monster, BlocksTile, Rect, Item, Potion, map::MAPWIDTH};
+
+/// Spawns the player and returns his/her entity object.
+pub fn player(ecs : &mut World, player_x : i32, player_y : i32) -> Entity {
+    ecs
+        .create_entity()
+        .with(Position { x: player_x, y: player_y })
+        .with(Renderable {
+            glyph: rltk::to_cp437('@'),
+            fg: RGB::named(rltk::YELLOW),
+            bg: RGB::named(rltk::BLACK),
+            render_order: 0
+        })
+        .with(Player{})
+        .with(Viewshed{ visible_tiles : Vec::new(), range: 8, dirty: true })
+        .with(Name{name: "Player".to_string() })
+        .with(CombatStats{ max_hp: 30, hp: 30, defense: 2, power: 5 })
+        .build()
+}
+
+const MAX_MONSTERS : i32 = 4;
+const MAX_ITEMS : i32 = 2;
+
+/// Fills a room with stuff!
+pub fn spawn_room(ecs: &mut World, room : &Rect) {
+    let mut monster_spawn_points : Vec<usize> = Vec::new();
+    let mut item_spawn_points : Vec<usize> = Vec::new();
+
+    // Scope to keep the borrow checker happy
+    {
+        let mut rng = ecs.write_resource::<RandomNumberGenerator>();
+        let num_monsters = rng.roll_dice(1, MAX_MONSTERS + 2) - 3;
+        let num_items = rng.roll_dice(1, MAX_ITEMS + 2) - 3;
+
+        for _i in 0 .. num_monsters {
+            let mut added = false;
+            while !added {
+                let x = (room.x1 + rng.roll_dice(1, i32::abs(room.x2 - room.x1))) as usize;
+                let y = (room.y1 + rng.roll_dice(1, i32::abs(room.y2 - room.y1))) as usize;
+                let idx = (y * MAPWIDTH) + x;
+                if !monster_spawn_points.contains(&idx) {
+                    monster_spawn_points.push(idx);
+                    added = true;
+                }
+            }
+        }
+
+        for _i in 0 .. num_items {
+            let mut added = false;
+            while !added {
+                let x = (room.x1 + rng.roll_dice(1, i32::abs(room.x2 - room.x1))) as usize;
+                let y = (room.y1 + rng.roll_dice(1, i32::abs(room.y2 - room.y1))) as usize;
+                let idx = (y * MAPWIDTH) + x;
+                if !item_spawn_points.contains(&idx) {
+                    item_spawn_points.push(idx);
+                    added = true;
+                }
+            }
+        }
+    }
+
+    // Actually spawn the monsters
+    for idx in monster_spawn_points.iter() {
+        let x = *idx % MAPWIDTH;
+        let y = *idx / MAPWIDTH;
+        random_monster(ecs, x as i32, y as i32);
+    }
+
+    // Actually spawn the potions
+    for idx in item_spawn_points.iter() {
+        let x = *idx % MAPWIDTH;
+        let y = *idx / MAPWIDTH;
+        health_potion(ecs, x as i32, y as i32);
+    }
+}
+
+fn random_monster(ecs: &mut World, x: i32, y: i32) {
+    let roll :i32;
+    {
+        let mut rng = ecs.write_resource::<RandomNumberGenerator>();
+        roll = rng.roll_dice(1, 2);
+    }
+    match roll {
+        1 => { orc(ecs, x, y) }
+        _ => { goblin(ecs, x, y) }
+    }
+}
+
+fn orc(ecs: &mut World, x: i32, y: i32) { monster(ecs, x, y, rltk::to_cp437('o'), "Orc"); }
+fn goblin(ecs: &mut World, x: i32, y: i32) { monster(ecs, x, y, rltk::to_cp437('g'), "Goblin"); }
+
+fn monster<S : ToString>(ecs: &mut World, x: i32, y: i32, glyph : u8, name : S) {
+    ecs.create_entity()
+        .with(Position{ x, y })
+        .with(Renderable{
+            glyph,
+            fg: RGB::named(rltk::RED),
+            bg: RGB::named(rltk::BLACK),
+            render_order: 1
+        })
+        .with(Viewshed{ visible_tiles : Vec::new(), range: 8, dirty: true })
+        .with(Monster{})
+        .with(Name{ name : name.to_string() })
+        .with(BlocksTile{})
+        .with(CombatStats{ max_hp: 16, hp: 16, defense: 1, power: 4 })
+        .build();
+}
+
+fn health_potion(ecs: &mut World, x: i32, y: i32) {
+    ecs.create_entity()
+        .with(Position{ x, y })
+        .with(Renderable{
+            glyph: rltk::to_cp437('¡'),
+            fg: RGB::named(rltk::MAGENTA),
+            bg: RGB::named(rltk::BLACK),
+            render_order: 2
+        })
+        .with(Name{ name : "Health Potion".to_string() })
+        .with(Item{})
+        .with(Potion{ heal_amount: 8 })
+        .build();
+}

chapter-10-ranged/src/visibility_system.rs

@@ -0,0 +1,37 @@
+extern crate specs;
+use specs::prelude::*;
+use super::{Viewshed, Position, Map, Player};
+extern crate rltk;
+use rltk::{field_of_view, Point};
+
+pub struct VisibilitySystem {}
+
+impl<'a> System<'a> for VisibilitySystem {
+    type SystemData = ( WriteExpect<'a, Map>,
+                        Entities<'a>,
+                        WriteStorage<'a, Viewshed>, 
+                        ReadStorage<'a, Position>,
+                        ReadStorage<'a, Player>);
+
+    fn run(&mut self, data : Self::SystemData) {
+        let (mut map, entities, mut viewshed, pos, player) = data;
+
+        for (ent,viewshed,pos) in (&entities, &mut viewshed, &pos).join() {
+            if viewshed.dirty {
+                viewshed.dirty = false;
+                viewshed.visible_tiles = field_of_view(Point::new(pos.x, pos.y), viewshed.range, &*map);
+
+                // If this is the player, reveal what they can see
+                let _p : Option<&Player> = player.get(ent);
+                if let Some(_p) = _p {
+                    for t in map.visible_tiles.iter_mut() { *t = false };
+                    for vis in viewshed.visible_tiles.iter() {
+                        let idx = map.xy_idx(vis.x, vis.y);
+                        map.revealed_tiles[idx] = true;
+                        map.visible_tiles[idx] = true;
+                    }
+                }
+            }
+        }
+    }
+}