Timer

Cargo.lock

@@ -609,6 +609,7 @@ dependencies = [
  "color",
  "rhai",
  "serde",
+ "tinyrand",
  "toml",
 ]
 
@@ -1520,6 +1521,12 @@ dependencies = [
  "crunchy",
 ]
 
+[[package]]
+name = "tinyrand"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "87ffaad2263779579369d45f65cad0647c860893d27e4543cdcc1e428d07da2c"
+
 [[package]]
 name = "toml"
 version = "0.8.23"

kiln-core/Cargo.toml

@@ -7,4 +7,5 @@ edition = "2024"
 color = "0.3.3"
 rhai = "1"
 serde = { version = "1", features = ["derive"] }
+tinyrand = "0.5"
 toml = { version = "0.8", features = ["preserve_order"] }

kiln-core/src/game.rs

@@ -3,6 +3,8 @@ use color::Rgba8;
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 use std::hash::{Hash, Hasher};
+use std::time::{Duration, SystemTime, UNIX_EPOCH};
+use tinyrand::{Rand, Seeded, StdRand};
 
 /// The visual representation of a single board cell.
 ///
@@ -397,14 +399,26 @@ pub struct GameState {
     pub board: Board,
     /// The in-game message log, oldest first (newest pushed at the end).
     pub log: Vec<LogLine>,
+    /// Elapsed real time not yet consumed by [`GameState::tick`], used to fire
+    /// once-per-second events regardless of the actual frame rate.
+    tick_accum: Duration,
+    /// The engine's random-number generator (currently used for tick colors).
+    rng: StdRand,
 }
 
 impl GameState {
     /// Creates a `GameState` from a pre-loaded [`Board`].
     pub fn new(board: Board) -> Self {
+        // Seed the RNG from the wall clock so colors differ run-to-run.
+        let seed = SystemTime::now()
+            .duration_since(UNIX_EPOCH)
+            .map(|d| d.as_nanos() as u64)
+            .unwrap_or(0);
         Self {
             board,
             log: Vec::new(),
+            tick_accum: Duration::ZERO,
+            rng: StdRand::seed(seed),
         }
     }
 
@@ -413,6 +427,29 @@ impl GameState {
         self.log.push(line);
     }
 
+    /// Advances real-time game state by `dt` (the elapsed time since the last
+    /// tick). Called once per frame by the front-end's game loop.
+    ///
+    /// For now this is a demo: it logs the word "tick" once per elapsed second,
+    /// each in a random bright color. A `while` loop (rather than `if`) keeps the
+    /// count correct even if a frame ran long enough to span multiple seconds.
+    pub fn tick(&mut self, dt: Duration) {
+        self.tick_accum += dt;
+        while self.tick_accum >= Duration::from_secs(1) {
+            self.tick_accum -= Duration::from_secs(1);
+            let color = self.random_color();
+            self.log(LogLine::new().push("tick", Some(color), None));
+        }
+    }
+
+    /// Returns a random fully-saturated, full-value color by picking a random
+    /// hue — bright enough to stay readable against dark backgrounds.
+    fn random_color(&mut self) -> Rgba8 {
+        let hue = self.rng.next_lim_u32(360) as f32;
+        let (r, g, b) = hue_to_rgb(hue);
+        Rgba8 { r, g, b, a: 255 }
+    }
+
     /// Attempts to move the player by `(dx, dy)` cells.
     ///
     /// The move is ignored if the target cell is out of bounds or its behavior
@@ -430,3 +467,64 @@ impl GameState {
         }
     }
 }
+
+/// Converts a hue in degrees to an RGB triple at full saturation and value.
+///
+/// Standard 6-segment HSV→RGB conversion (S = V = 1). Kept here rather than
+/// shared with the front-end because kiln-core does not depend on any UI crate;
+/// `kiln-tui` has its own copy for the terminal-status badge.
+fn hue_to_rgb(hue: f32) -> (u8, u8, u8) {
+    let h = (hue % 360.0) / 60.0;
+    // `x` ramps the secondary channel up/down within each 60° segment.
+    let x = 1.0 - (h % 2.0 - 1.0).abs();
+    let (r, g, b) = match h as u32 {
+        0 => (1.0, x, 0.0),
+        1 => (x, 1.0, 0.0),
+        2 => (0.0, 1.0, x),
+        3 => (0.0, x, 1.0),
+        4 => (x, 0.0, 1.0),
+        _ => (1.0, 0.0, x),
+    };
+    ((r * 255.0) as u8, (g * 255.0) as u8, (b * 255.0) as u8)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// A minimal 1×1 empty board for exercising `GameState` logic.
+    fn empty_board() -> Board {
+        Board {
+            name: "test".into(),
+            width: 1,
+            height: 1,
+            cells: vec![(Archetype::Empty.default_glyph(), Archetype::Empty)],
+            player: Player { x: 0, y: 0 },
+            objects: Vec::new(),
+            portals: Vec::new(),
+            font: None,
+            zoom: 1,
+            scripts: HashMap::new(),
+            board_script_name: None,
+        }
+    }
+
+    #[test]
+    fn tick_logs_one_message_per_elapsed_second() {
+        let mut game = GameState::new(empty_board());
+        assert_eq!(game.log.len(), 0);
+
+        // Under a second of accumulated time logs nothing yet.
+        game.tick(Duration::from_millis(500));
+        assert_eq!(game.log.len(), 0);
+
+        // Crossing the one-second mark logs exactly one "tick".
+        game.tick(Duration::from_millis(600));
+        assert_eq!(game.log.len(), 1);
+        assert_eq!(game.log[0].spans[0].text, "tick");
+
+        // A single long frame logs one message per whole second it spans.
+        game.tick(Duration::from_secs(3));
+        assert_eq!(game.log.len(), 4);
+    }
+}

kiln-tui/src/main.rs

@@ -26,6 +26,7 @@ use ratatui::widgets::{Block, Paragraph, Wrap};
 use render::{BoardWidget, logline_to_line};
 use std::io;
 use std::process::ExitCode;
+use std::time::{Duration, Instant};
 use ratatui::symbols::merge::MergeStrategy;
 use term::TerminalCaps;
 
@@ -107,34 +108,43 @@ fn main() -> ExitCode {
     ExitCode::SUCCESS
 }
 
-/// Draw-then-handle-input loop. Returns once the user asks to quit.
+/// The target frame interval: 30 frames per second.
+const FRAME: Duration = Duration::from_nanos(1_000_000_000 / 30);
+
+/// Real-time draw / input / update loop at ~30 FPS. Returns once the user quits.
+///
+/// Unlike a turn-based loop, this never blocks indefinitely: it waits for input
+/// only until the next frame deadline (`event::poll`), then advances the game by
+/// the real time elapsed since the last tick. `poll` returns the instant a key
+/// arrives, so input stays responsive while the game keeps ticking on its own.
 fn run(
     terminal: &mut ratatui::DefaultTerminal,
     game: &mut GameState,
     ui: &mut Ui,
 ) -> std::io::Result<()> {
+    let mut last_tick = Instant::now();
     loop {
         // Redraw every iteration; ratatui diffs against the previous frame so
         // only changed cells are actually written to the terminal.
         terminal.draw(|frame| draw(frame, game, ui))?;
 
-        match event::read()? {
-            Event::Key(key) => {
+        // Wait for input only up to the next frame deadline so the loop wakes to
+        // tick even with no keypresses.
+        let timeout = FRAME.saturating_sub(last_tick.elapsed());
+        if event::poll(timeout)? {
+            match event::read()? {
                 // Act on Press and Repeat so holding a key moves the player
-                // continuously (the Kitty protocol emits Repeat events while a
-                // key is held). Ignore Release, which that protocol also emits
-                // and which would otherwise fire a second, spurious move.
-                if key.kind == KeyEventKind::Release {
-                    continue;
-                }
-                match key.code {
+                // continuously (the Kitty protocol emits Repeat events while a key
+                // is held). Ignore Release, which that protocol also emits and
+                // which would otherwise fire a second, spurious move per keypress.
+                Event::Key(key) if key.kind != KeyEventKind::Release => match key.code {
                     KeyCode::Char('q') | KeyCode::Esc => return Ok(()),
                     KeyCode::Up => game.try_move(0, -1),
                     KeyCode::Down => game.try_move(0, 1),
                     KeyCode::Left => game.try_move(-1, 0),
-                    // Right arrow moves right; 'l' is reserved for the log panel.
+                    // Right arrow moves right; 'l' is the log panel.
                     KeyCode::Right => game.try_move(1, 0),
-                    // 'l' toggles the log panel; reset the scroll to the newest.
+                    // 'l' toggles the log panel; reset scroll to newest.
                     KeyCode::Char('l') => {
                         ui.log_open = !ui.log_open;
                         ui.scroll = 0;
@@ -143,22 +153,31 @@ fn run(
                     KeyCode::PageUp if ui.log_open => scroll_log(ui, game, -5),
                     KeyCode::PageDown if ui.log_open => scroll_log(ui, game, 5),
                     _ => {}
-                }
-            }
-            // Wheel scrolls the open log; dragging the divider resizes it.
-            Event::Mouse(m) if ui.log_open => match m.kind {
-                MouseEventKind::ScrollUp => scroll_log(ui, game, -1),
-                MouseEventKind::ScrollDown => scroll_log(ui, game, 1),
-                MouseEventKind::Drag(_) => {
-                    // The divider sits at row `total - log_height`; dragging it up
-                    // (smaller row) grows the panel. Keep both regions usable.
-                    let total = terminal.size()?.height;
-                    let target = total.saturating_sub(m.row);
-                    ui.log_height = target.clamp(3, total.saturating_sub(3).max(3));
-                }
+                },
+                // Wheel scrolls the open log; dragging the divider resizes it.
+                Event::Mouse(m) if ui.log_open => match m.kind {
+                    MouseEventKind::ScrollUp => scroll_log(ui, game, -1),
+                    MouseEventKind::ScrollDown => scroll_log(ui, game, 1),
+                    MouseEventKind::Drag(_) => {
+                        // The divider sits at row `total - log_height`; dragging
+                        // it up (smaller row) grows the panel. Keep both usable.
+                        let total = terminal.size()?.height;
+                        let target = total.saturating_sub(m.row);
+                        ui.log_height = target.clamp(3, total.saturating_sub(3).max(3));
+                    }
+                    _ => {}
+                },
                 _ => {}
-            },
-            _ => {}
+            }
+        }
+
+        // Advance the game by the real time elapsed since the last tick. Only
+        // resetting `last_tick` when we actually tick means time spent waiting on
+        // input (or skipped Release events) is preserved in the next `dt`.
+        if last_tick.elapsed() >= FRAME {
+            let dt = last_tick.elapsed();
+            last_tick = Instant::now();
+            game.tick(dt);
         }
     }
 }