fov

kiln-tui/Cargo.toml

@@ -9,3 +9,7 @@ kiln-core = { path = "../kiln-core" }
 kiln-ui = { git = "https://notpi.com/randrews/kiln-ui.git" }
 color = "0.3.3"
 ratatui = { workspace = true, features = ["unstable-rendered-line-info"] }
+
+[dev-dependencies]
+# Used only by rendering tests to build a Board from an inline map-file string.
+toml = { version = "0.8", features = ["preserve_order"] }

kiln-tui/src/main.rs

@@ -424,7 +424,14 @@ fn draw_board_area(frame: &mut Frame, inner: Rect, game: &GameState, ui: &mut Ui
         );
     } else {
         let board = &game.board();
-        frame.render_widget(BoardWidget::new(board), inner);
-        frame.render_widget(SpeechBubblesWidget::new(board, &game.speech_bubbles), inner);
+        // On a dark board this is the player's field of view; on a lit board it's
+        // None (draw everything). Computed once and shared by both widgets so the
+        // board and its speech bubbles agree on what's visible.
+        let fov = board.player_fov();
+        frame.render_widget(BoardWidget::new(board).fov(fov.as_ref()), inner);
+        frame.render_widget(
+            SpeechBubblesWidget::new(board, &game.speech_bubbles).fov(fov.as_ref()),
+            inner,
+        );
     }
 }

kiln-tui/src/render.rs

@@ -6,12 +6,19 @@
 //! player is drawn on top of everything.
 
 use crate::utils::rgba8_to_color;
+use color::Rgba8;
 use kiln_core::Board;
+use kiln_core::Visibility;
 use kiln_core::cp437::tile_to_char;
 use ratatui::buffer::Buffer;
 use ratatui::layout::Rect;
 use ratatui::widgets::Widget;
 
+/// The background color drawn for cells outside the field of view on a dark
+/// board — a near-black gray, so unseen terrain reads as "dark" rather than
+/// pure void (which is what the normal empty floor already is).
+const DARKNESS_BG: Rgba8 = Rgba8 { r: 32, g: 32, b: 32, a: 255 };
+
 /// A ratatui widget that draws a [`Board`] (with objects and the player) into a
 /// rectangular area, scrolled so a chosen focus cell stays visible on larger boards.
 pub struct BoardWidget<'a> {
@@ -20,13 +27,17 @@ pub struct BoardWidget<'a> {
     /// The board cell (x, y) the viewport scrolls to keep visible. Defaults to
     /// the player position so play mode requires no extra setup.
     focus: (i32, i32),
+    /// The player's field of view on a [`dark`](Board::dark) board, if any. When
+    /// `Some`, cells not in view are drawn as darkness instead of their glyph.
+    /// `None` (a lit board) draws every cell normally.
+    fov: Option<&'a Visibility>,
 }
 
 impl<'a> BoardWidget<'a> {
     /// Creates a widget that renders `board`, scrolling to follow the player.
     pub fn new(board: &'a Board) -> Self {
         let focus = (board.player.x as i32, board.player.y as i32);
-        Self { board, focus }
+        Self { board, focus, fov: None }
     }
 
     /// Overrides the scroll focus to `(x, y)` — use in the editor to follow the
@@ -36,6 +47,13 @@ impl<'a> BoardWidget<'a> {
         self
     }
 
+    /// Supplies the player's field of view (see [`Board::player_fov`]). When
+    /// `Some`, cells outside it render as darkness; `None` renders everything.
+    pub fn fov(mut self, fov: Option<&'a Visibility>) -> Self {
+        self.fov = fov;
+        self
+    }
+
     /// Lays out one axis of the board within a viewport `view` cells long.
     ///
     /// Returns `(off, pad, count)` where `off` is the first board cell to draw,
@@ -113,9 +131,106 @@ pub fn screen_to_board(
     Some((off_x + col as usize, off_y + row as usize))
 }
 
+impl Widget for BoardWidget<'_> {
+    fn render(self, area: Rect, buf: &mut Buffer) {
+        let board = self.board;
+        // Resolve each axis independently: a small board is centered, a large
+        // one scrolls to keep the focus cell on screen.
+        let (off_x, pad_x, cols) = Self::axis(board.width, area.width as usize, self.focus.0);
+        let (off_y, pad_y, rows) = Self::axis(board.height, area.height as usize, self.focus.1);
+
+        // Walk the visible board cells, placing each after the centering pad.
+        for row in 0..rows {
+            let by = off_y + row;
+            let sy = area.y + pad_y + row as u16;
+            for col in 0..cols {
+                let bx = off_x + col;
+                let sx = area.x + pad_x + col as u16;
+
+                // On a dark board, a cell outside the player's field of view is
+                // drawn as darkness (blank cell, dark-gray background) instead of
+                // its real glyph. A lit board (`fov == None`) shows every cell.
+                let visible = self.fov.is_none_or(|v| v.is_visible(bx, by));
+                if let Some(cell) = buf.cell_mut((sx, sy)) {
+                    if visible {
+                        let glyph = board.glyph_at(bx, by);
+                        cell.set_char(tile_to_char(glyph.tile))
+                            .set_fg(rgba8_to_color(glyph.fg))
+                            .set_bg(rgba8_to_color(glyph.bg));
+                    } else {
+                        cell.set_char(' ')
+                            .set_fg(rgba8_to_color(DARKNESS_BG))
+                            .set_bg(rgba8_to_color(DARKNESS_BG));
+                    }
+                }
+            }
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
-    use super::BoardWidget;
+    use super::{BoardWidget, DARKNESS_BG};
+    use crate::utils::rgba8_to_color;
+    use kiln_core::Board;
+    use kiln_core::map_file::MapFile;
+    use ratatui::buffer::Buffer;
+    use ratatui::layout::Rect;
+    use ratatui::widgets::Widget;
+
+    /// Builds a tiny dark board: a 5×1 corridor with the player at the left end
+    /// and a wall at x=2 occluding the two cells behind it.
+    fn dark_corridor() -> Board {
+        let toml = r##"
+            [map]
+            name = "corridor"
+            width = 5
+            height = 1
+            dark = true
+            [grid]
+            content = "@ #  "
+            [grid.palette]
+            "@" = { kind = "player" }
+            "#" = { kind = "wall", tile = "#", fg = "#808080", bg = "#404040" }
+        "##;
+        let mf: MapFile = toml::from_str(toml).unwrap();
+        Board::try_from(mf).unwrap()
+    }
+
+    #[test]
+    fn dark_board_renders_occluded_cells_as_darkness() {
+        let board = dark_corridor();
+        let fov = board.player_fov();
+        assert!(fov.is_some(), "a dark board must produce a field of view");
+
+        let area = Rect::new(0, 0, 5, 1);
+        let mut buf = Buffer::empty(area);
+        BoardWidget::new(&board).fov(fov.as_ref()).render(area, &mut buf);
+
+        // The wall at x=2 is visible (light_walls); the cells behind it are drawn
+        // as darkness: a blank cell on the dark-gray background.
+        let dark = rgba8_to_color(DARKNESS_BG);
+        assert_eq!(buf[(2, 0)].symbol(), "#", "the wall itself is lit");
+        for x in [3u16, 4] {
+            let cell = &buf[(x, 0)];
+            assert_eq!(cell.symbol(), " ", "occluded cell is blank");
+            assert_eq!(cell.bg, dark, "occluded cell uses the darkness background");
+        }
+    }
+
+    #[test]
+    fn lit_board_renders_every_cell_normally() {
+        // The same board without `dark` gets no FOV, so nothing is hidden.
+        let mut board = dark_corridor();
+        board.dark = false;
+        assert!(board.player_fov().is_none());
+
+        let area = Rect::new(0, 0, 5, 1);
+        let mut buf = Buffer::empty(area);
+        BoardWidget::new(&board).fov(None).render(area, &mut buf);
+        // The far cell behind the wall is drawn from the board, not as darkness.
+        assert_ne!(buf[(4, 0)].bg, rgba8_to_color(DARKNESS_BG));
+    }
 
     #[test]
     fn axis_centers_a_small_board() {
@@ -139,32 +254,3 @@ mod tests {
         assert_eq!(BoardWidget::axis(100, 20, 99), (80, 0, 20));
     }
 }
-
-impl Widget for BoardWidget<'_> {
-    fn render(self, area: Rect, buf: &mut Buffer) {
-        let board = self.board;
-        // Resolve each axis independently: a small board is centered, a large
-        // one scrolls to keep the focus cell on screen.
-        let (off_x, pad_x, cols) = Self::axis(board.width, area.width as usize, self.focus.0);
-        let (off_y, pad_y, rows) = Self::axis(board.height, area.height as usize, self.focus.1);
-
-        // Walk the visible board cells, placing each after the centering pad.
-        for row in 0..rows {
-            let by = off_y + row;
-            let sy = area.y + pad_y + row as u16;
-            for col in 0..cols {
-                let bx = off_x + col;
-                let sx = area.x + pad_x + col as u16;
-
-                let glyph = board.glyph_at(bx, by);
-
-                // Paint the resolved glyph into the terminal cell.
-                if let Some(cell) = buf.cell_mut((sx, sy)) {
-                    cell.set_char(tile_to_char(glyph.tile))
-                        .set_fg(rgba8_to_color(glyph.fg))
-                        .set_bg(rgba8_to_color(glyph.bg));
-                }
-            }
-        }
-    }
-}

kiln-tui/src/speech.rs

@@ -1,7 +1,7 @@
 use crate::render::BoardWidget;
 use crate::utils::rects_overlap;
 use kiln_core::game::SpeechBubble;
-use kiln_core::{Board, Direction};
+use kiln_core::{Board, Direction, Visibility};
 use ratatui::buffer::Buffer;
 use ratatui::layout::Rect;
 use ratatui::prelude::{Color, Line, Style, Widget};
@@ -19,6 +19,10 @@ pub struct SpeechBubblesWidget<'a> {
     pub board: &'a Board,
     /// The active speech bubbles to render.
     pub bubbles: &'a [SpeechBubble],
+    /// The player's field of view on a dark board, if any. A speaker outside it
+    /// still gets a bubble, but with no tail (like an off-screen speaker) —
+    /// you hear the unseen thing without a line pointing to where it hides.
+    fov: Option<&'a Visibility>,
 }
 
 /// A fully-resolved bubble placement ready for the three draw passes.
@@ -40,7 +44,14 @@ struct Placement<'a> {
 impl<'a> SpeechBubblesWidget<'a> {
     /// Creates a widget for the given board and bubble slice.
     pub fn new(board: &'a Board, bubbles: &'a [SpeechBubble]) -> Self {
-        Self { board, bubbles }
+        Self { board, bubbles, fov: None }
+    }
+
+    /// Supplies the player's field of view (see [`Board::player_fov`]). A speaker
+    /// outside it has its tail suppressed; `None` (a lit board) leaves tails as-is.
+    pub fn fov(mut self, fov: Option<&'a Visibility>) -> Self {
+        self.fov = fov;
+        self
     }
 
     /// Places a bubble for a speaker at `(obj_sx, obj_sy)`.
@@ -117,7 +128,10 @@ impl Widget for SpeechBubblesWidget<'_> {
             .filter_map(|b| {
                 let obj = self.board.objects.get(&b.object_id)?;
                 let (sx, sy, on_screen) = board_screen_pos(area, self.board, obj.x, obj.y);
-                Some((sx, sy, on_screen, b))
+                // On a dark board, a speaker the player can't see is treated like an
+                // off-screen speaker: the box still draws, but its tail is suppressed.
+                let visible = self.fov.is_none_or(|v| v.is_visible(obj.x, obj.y));
+                Some((sx, sy, on_screen && visible, b))
             })
             .collect();