Set up discovery system

src/components.rs

@@ -16,9 +16,12 @@ pub struct CharRender {
     pub glyph: char,
 }
 
-/// Entities that the user can control using the keyboard.
+/// Entities that users can control.
 #[derive(Component)]
-pub struct Player;
+pub struct Player {
+    /// The list of cells that are known to the player.
+    pub known_cells: Vec<Vec<bool>>,
+}
 
 /// Entities that take turns periodically.
 #[derive(Component)]
@@ -46,6 +49,18 @@ pub fn register_all(world: &mut World) {
     world.register::<Mobile>();
 }
 
+impl From<&Position> for (i32, i32) {
+    fn from(pos: &Position) -> Self {
+        (pos.x, pos.y)
+    }
+}
+
+impl From<(i32, i32)> for Position {
+    fn from((x, y): (i32, i32)) -> Self {
+        Self { x, y }
+    }
+}
+
 /// An action that a mob can perform that takes up a turn.
 #[derive(Clone, Copy)]
 pub enum MobAction {

src/level.rs

@@ -4,7 +4,12 @@ use pancurses::Window;
 use rand::Rng;
 use specs::prelude::*;
 
-use crate::{components::{CharRender, Position}, io::{Color, set_color}, rooms};
+use crate::{
+    components::{CharRender, Position},
+    io::{set_color, Color},
+    rooms,
+    visibility::{visible, CellVisibility, Lighting},
+};
 
 /// The size of a dungeon level, in tiles.
 pub const LEVEL_SIZE: (usize, usize) = (80, 24);
@@ -39,6 +44,23 @@ pub enum DungeonTile {
     Downstair,
 }
 
+/// A style for drawing a particular tile in the dungeon.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum DrawStyle {
+    /// Don't draw the tile. (The player has never seen this tile
+    /// before, and is unaware of its contents.)
+    Undiscovered,
+
+    /// Draw the tile in a darker color than normal. (The player has
+    /// seen this tile before and remembers its contents, but is not
+    /// actively looking at it.)
+    Discovered,
+
+    /// Draw the tile in a normal color. (The player can see the tile
+    /// from where they are standing.)
+    Visible,
+}
+
 impl DungeonTile {
     /// Whether this tile is considered a floor tile, for the purposes
     /// of rendering walls.
@@ -99,20 +121,22 @@ impl DungeonLevel {
     /// Draws a level on the display window. Draws only the cells for
     /// which `filter` returns true; use `|_| true` to draw the whole
     /// level.
-    pub fn draw(&self, win: &Window, filter: impl Fn((i32, i32)) -> bool) {
+    pub fn draw(&self, win: &Window, visibility: impl Fn((i32, i32)) -> DrawStyle) {
         for y in 0..LEVEL_SIZE.1 {
             win.mv(y as _, 0);
             for x in 0..LEVEL_SIZE.0 {
-                if (x + y) % 2 == 0 {
-                    set_color(win, Color::Yellow);
-                } else {
+                win.addch(match visibility((x as _, y as _)) {
+                    DrawStyle::Undiscovered => ' ',
+                    DrawStyle::Discovered => {
+                        // Using red as a placeholder; black doesn't
+                        // seem to work rn(?)
                         set_color(win, Color::Red);
-                }
-
-                win.addch(if filter((x as _, y as _)) {
                         self.render_tile(x, y)
-                } else {
-                    ' '
+                    }
+                    DrawStyle::Visible => {
+                        set_color(win, Color::White);
+                        self.render_tile(x, y)
+                    }
                 });
             }
         }
@@ -168,6 +192,25 @@ impl DungeonLevel {
     pub fn tile(&self, x: i32, y: i32) -> &DungeonTile {
         &self.tiles[y as usize][x as usize]
     }
+
+    /// Whether a monster standing at `from` can see the contents of cell
+    /// `to`.
+    pub fn can_see(&self, from: (i32, i32), to: (i32, i32)) -> bool {
+        visible(
+            from,
+            to,
+            Some(10),
+            |(x, y)| {
+                if self.tile(x, y).is_navigable() {
+                    CellVisibility::Transparent
+                } else {
+                    CellVisibility::Blocking
+                }
+            },
+            // Level is fully lit for now.
+            |(_x, _y)| Lighting::Lit,
+        )
+    }
 }
 
 impl Display for DungeonLevel {

src/main.rs

@@ -1,11 +1,11 @@
 use components::{register_all, CharRender, MobAction, Mobile, Player, Position, TurnTaker};
 use io::init_window;
-use level::DungeonLevel;
+use level::{DungeonLevel, LEVEL_SIZE};
 
 use player::player_turn;
 use rand::thread_rng;
 use specs::prelude::*;
-use systems::{MobSystem, TimeSystem};
+use systems::{DiscoverySystem, MobSystem, TimeSystem};
 
 mod components;
 mod io;
@@ -28,12 +28,13 @@ fn main() {
 
     world
         .create_entity()
-        .with(Position {
-            x: spawn_pos.0,
-            y: spawn_pos.1,
-        })
+        .with(Position::from(spawn_pos))
         .with(CharRender { glyph: '@' })
-        .with(Player)
+        .with(Player {
+            known_cells: (0..LEVEL_SIZE.1)
+                .map(|_| (0..LEVEL_SIZE.0).map(|_| false).collect())
+                .collect(),
+        })
         .with(Mobile {
             next_action: MobAction::Nop,
         })
@@ -46,6 +47,7 @@ fn main() {
     let mut dispatcher = DispatcherBuilder::new()
         .with(TimeSystem, "time", &[])
         .with(MobSystem, "mobs", &[])
+        .with(DiscoverySystem, "discovery", &[])
         .build();
 
     let mut window = match init_window() {
@@ -53,7 +55,7 @@ fn main() {
         Err(err) => {
             println!("Error initializing window: {}", err);
             return;
-        },
+        }
     };
 
     loop {

src/player.rs

@@ -5,9 +5,8 @@ use specs::prelude::*;
 
 use crate::{
     components::{CharRender, MobAction, Mobile, Player, Position},
-    level::DungeonLevel,
     io::quit,
-    visibility::{visible, CellVisibility, Lighting},
+    level::{DrawStyle, DungeonLevel},
 };
 
 /// Runs a player turn on the ECS, using the given `screen` for input
@@ -96,21 +95,18 @@ fn render_screen(ecs: &mut World, screen: &mut Window) {
 
     // Draw the base level.
     let level = ecs.fetch::<DungeonLevel>();
+    let known_cells = &plrs.join().next().expect("Player must exist").known_cells;
     level.draw(screen, |cell| {
-        visible(
-            (player_pos.x, player_pos.y),
-            cell,
-            Some(10),
-            |(x, y)| {
-                if level.tile(x, y).is_navigable() {
-                    CellVisibility::Transparent
+        match level.can_see(player_pos.into(), cell) {
+            true => DrawStyle::Visible,
+            false => {
+                if known_cells[cell.1 as usize][cell.0 as usize] {
+                    DrawStyle::Discovered
                 } else {
-                    CellVisibility::Blocking
+                    DrawStyle::Undiscovered
+                }
+            }
         }
-            },
-            // Level is fully lit for now.
-            |(_x, _y)| Lighting::Lit,
-        )
     });
 
     // Draw all renderable entities.

src/systems.rs

@@ -2,7 +2,10 @@
 
 use specs::prelude::*;
 
-use crate::components::{MobAction, Mobile, Position, TurnTaker};
+use crate::{
+    components::{MobAction, Mobile, Player, Position, TurnTaker},
+    level::DungeonLevel,
+};
 
 /// System for ticking the turn counter on every entity; this system
 /// implements the relationship between real-world time and in-game
@@ -46,3 +49,26 @@ impl<'a> System<'a> for MobSystem {
         }
     }
 }
+
+/// System for updating player-discovered cells.
+pub struct DiscoverySystem;
+
+impl<'a> System<'a> for DiscoverySystem {
+    type SystemData = (
+        WriteStorage<'a, Player>,
+        ReadStorage<'a, Position>,
+        ReadExpect<'a, DungeonLevel>,
+    );
+
+    fn run(&mut self, (mut players, position, level): Self::SystemData) {
+        for (player, pos) in (&mut players, &position).join() {
+            for (y, row) in player.known_cells.iter_mut().enumerate() {
+                for (x, known) in row.iter_mut().enumerate() {
+                    if level.can_see(pos.into(), (x as _, y as _)) {
+                        *known = true;
+                    }
+                }
+            }
+        }
+    }
+}

src/visibility.rs

@@ -14,10 +14,9 @@ pub enum CellVisibility {
 /// How well-lit a cell is.
 #[derive(Debug, PartialEq)]
 pub enum Lighting {
-    /// Monsters can only see in this cell if the cell is immediately
-    /// adjacent to the monster.
-    Dark,
-
+    // /// Monsters can only see in this cell if the cell is immediately
+    // /// adjacent to the monster.
+    // Dark,
     /// Monsters can see in this cell from far away.
     Lit,
 }