Add chapter 2.1-end

src/main.rs

@@ -0,0 +1,97 @@
+use rltk::{GameState, Rltk, RGB};
+
+use specs::prelude::*;
+use specs_derive::Component;
+use std::cmp::{max, min};
+
+#[derive(Component)]
+struct Position {
+    x: i32,
+    y: i32,
+}
+
+#[derive(Component)]
+struct Renderable {
+    glyph: rltk::FontCharType,
+    fg: RGB,
+    bg: RGB,
+}
+
+#[derive(Component, Debug)]
+struct Player {}
+
+struct State {
+    ecs: World,
+}
+
+impl State {
+    fn run_systems(&mut self) {
+        let mut lw = LeftWalker {};
+        lw.run_now(&self.ecs);
+        self.ecs.maintain();
+    }
+}
+
+fn try_move_player(delta_x: i32, delta_y: i32, ecs: &mut World) {
+    let mut positions = ecs.write_storage::<Position>();
+    let mut players = ecs.write_storage::<Player>();
+
+    for (_player, pos) in (&mut players, &mut positions).join() {
+        pos.x = min(79, max(0, pos.x + delta_x));
+        pos.y = min(49, max(0, pos.y + delta_y));
+    }
+}
+
+fn player_input(gs: &mut State, ctx: &mut Rltk) {
+    match ctx.key {
+        None => {}
+        Some(key) => match key {
+            rltk::VirtualKeyCode::Left => try_move_player(-1, 0, &mut gs.ecs),
+            rltk::VirtualKeyCode::Right => try_move_player(1, 0, &mut gs.ecs),
+            rltk::VirtualKeyCode::Up => try_move_player(0, -1, &mut gs.ecs),
+            rltk::VirtualKeyCode::Down => try_move_player(0, 1, &mut gs.ecs),
+            _ => {}
+        },
+    }
+}
+
+impl GameState for State {
+    fn tick(&mut self, ctx: &mut rltk::Rltk) {
+        ctx.cls();
+
+        player_input(self, ctx);
+        self.run_systems();
+
+        let positions = self.ecs.read_storage::<Position>();
+        let renderables = self.ecs.read_storage::<Renderable>();
+
+        for (pos, render) in (&positions, &renderables).join() {
+            ctx.set(pos.x, pos.y, render.fg, render.bg, render.glyph)
+        }
+    }
+}
+
+fn main() -> rltk::BError {
+    use rltk::RltkBuilder;
+    let context = RltkBuilder::simple80x50()
+        .with_title("Roguelike Tutorial")
+        .build()?;
+    let mut gs = State { ecs: World::new() };
+
+    gs.ecs.register::<Position>();
+    gs.ecs.register::<Renderable>();
+    gs.ecs.register::<Player>();
+
+    gs.ecs
+        .create_entity()
+        .with(Position { x: 40, y: 25 })
+        .with(Renderable {
+            glyph: rltk::to_cp437('@'),
+            fg: RGB::named(rltk::YELLOW),
+            bg: RGB::named(rltk::BLACK),
+        })
+        .with(Player {})
+        .build();
+
+    rltk::main_loop(context, gs)
+}