Starting to get to grips with saving the game - save the map.

Cargo.lock

@@ -1137,6 +1137,7 @@ dependencies = [
  "rand_xorshift 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rayon 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.99 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_json 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)",
  "winit 0.20.0-alpha2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 

Cargo.toml

@@ -7,7 +7,7 @@ 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" }
+rltk = { git = "https://github.com/thebracket/rltk_rs", features = [ "serialization" ] }
 specs = "0.15.0"
 specs-derive = "0.4.0"
 

book/src/chapter_11.md

@@ -166,7 +166,7 @@ That's a bit of a mouthful, but it displays menu options and lets you select the
 
 ```toml
 [dependencies]
-rltk = { git = "https://github.com/thebracket/rltk_rs", features = ["serde"] }
+rltk = { git = "https://github.com/thebracket/rltk_rs", features = ["serialization"] }
 specs = { version = "0.15.0", features = ["serde"] }
 specs-derive = "0.4.0"
 serde= { version = "1.0.93", features = ["derive"] }
@@ -210,9 +210,60 @@ VirtualKeyCode::Escape => return RunState::SaveGame,
 
 If you `cargo run` now, you can start a game and press escape to quit to the menu.
 
-# Actually saving the game
+# Getting started with saving the game
 
-Now that the scaffolding is in place, it's time to actually save something!
+Now that the scaffolding is in place, it's time to actually save something! Lets start simple, to get a feel for Serde. In the `tick` function, we extend the save system to just dump a JSON representation of the map to the console:
+
+```rust
+RunState::SaveGame => {
+    let data = serde_json::to_string(&*self.ecs.fetch::<Map>()).unwrap();
+    println!("{}", data);
+
+    newrunstate = RunState::MainMenu{ menu_selection : gui::MainMenuSelection::LoadGame };
+}
+```
+
+We'll also need to add an `extern crate serde;` to the top of `main.rs`.
+
+This won't compile, because we need to tell `Map` to serialize itself! Fortunately, `serde` provides some helpers to make this easy. At the top of `map.rs`, we add `use serde::{Serialize, Deserialize};`. We then decorate the map to derive serialization and de-serialization code:
+
+```rust
+#[derive(Default, Serialize, Deserialize)]
+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>,
+
+    #[serde(skip_serializing)]
+    #[serde(skip_deserializing)]
+    pub tile_content : Vec<Vec<Entity>>
+}
+```
+
+Note that we've decorated `tile_content` with directives to not serialize/de-serialize it. This prevents us from needing to store the entities, and since this data is rebuilt every frame - it doesn't matter. The game still won't compile; we need to add similar decorators to `TileType` and `Rect`:
+
+```rust
+#[derive(PartialEq, Copy, Clone, Serialize, Deserialize)]
+pub enum TileType {
+    Wall, Floor
+}
+```
+
+```rust
+#[derive(PartialEq, Copy, Clone, Serialize, Deserialize)]
+pub struct Rect {
+    pub x1 : i32,
+    pub x2 : i32,
+    pub y1 : i32,
+    pub y2 : i32
+}
+```
+
+If you `cargo run` the project now, when you hit escape it will dump a huge blob of JSON data to the console. That's the game map!
 
 **The source code for this chapter may be found [here](https://github.com/thebracket/rustrogueliketutorial/tree/master/chapter-10-ranged)**
 

chapter-11-loadsave/Cargo.toml

@@ -7,7 +7,7 @@ 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", features = ["serde"] }
+rltk = { git = "https://github.com/thebracket/rltk_rs", features = ["serialization"] }
 specs = { version = "0.15.0", features = ["serde"] }
 specs-derive = "0.4.0"
 serde= { version = "1.0", features = ["derive"] }

chapter-11-loadsave/src/main.rs

@@ -160,7 +160,8 @@ impl GameState for State {
                 }
             }
             RunState::SaveGame => {
-                //let data = serde_json::to_string(&*self.ecs.fetch::<Map>()).unwrap();
+                let data = serde_json::to_string(&*self.ecs.fetch::<Map>()).unwrap();
+                println!("{}", data);
                 //let mut f = File::create("./savegame.json").expect("Unable to create file");
                 //f.write_all(data.as_bytes()).expect("Unable to write data");
 

chapter-11-loadsave/src/map.rs

@@ -4,17 +4,18 @@ use super::{Rect};
 use std::cmp::{max, min};
 extern crate specs;
 use specs::prelude::*;
+use serde::{Serialize, Deserialize};
 
 pub const MAPWIDTH : usize = 80;
 pub const MAPHEIGHT : usize = 43;
 pub const MAPCOUNT : usize = MAPHEIGHT * MAPWIDTH;
 
-#[derive(PartialEq, Copy, Clone)]
+#[derive(PartialEq, Copy, Clone, Serialize, Deserialize)]
 pub enum TileType {
     Wall, Floor
 }
 
-#[derive(Default)]
+#[derive(Default, Serialize, Deserialize)]
 pub struct Map {
     pub tiles : Vec<TileType>,
     pub rooms : Vec<Rect>,
@@ -23,6 +24,9 @@ pub struct Map {
     pub revealed_tiles : Vec<bool>,
     pub visible_tiles : Vec<bool>,
     pub blocked : Vec<bool>,
+
+    #[serde(skip_serializing)]
+    #[serde(skip_deserializing)]
     pub tile_content : Vec<Vec<Entity>>
 }
 

chapter-11-loadsave/src/rect.rs

@@ -1,3 +1,6 @@
+use serde::{Serialize, Deserialize};
+
+#[derive(PartialEq, Copy, Clone, Serialize, Deserialize)]
 pub struct Rect {
     pub x1 : i32,
     pub x2 : i32,