feat(city): style pack, tileset and lighting

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

crates/city/src/render/mod.rs

@@ -0,0 +1,112 @@
+//! Rendering: colours, cells, the render context and the tileset.
+
+pub mod lighting;
+pub mod style;
+pub mod tileset;
+
+use citygen::{BuildingKind, ConnectorKind, Pos, StratumKind, Theme};
+use ratatui::buffer::Buffer;
+use ratatui::style::{Color, Modifier, Style};
+use serde::{Deserialize, Serialize};
+use style::StylePack;
+
+/// A truecolor value.
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash, Serialize, Deserialize)]
+pub struct Rgb(pub u8, pub u8, pub u8);
+
+impl Rgb {
+    pub fn to_color(self) -> Color {
+        Color::Rgb(self.0, self.1, self.2)
+    }
+
+    /// Multiplies every channel, saturating at 255.
+    pub fn scale(self, f: f32) -> Rgb {
+        let s = |c: u8| ((c as f32) * f).round().clamp(0.0, 255.0) as u8;
+        Rgb(s(self.0), s(self.1), s(self.2))
+    }
+
+    /// Linear blend toward `other` by `t` in 0..=1.
+    pub fn mix(self, other: Rgb, t: f32) -> Rgb {
+        let t = t.clamp(0.0, 1.0);
+        let m = |a: u8, b: u8| ((a as f32) + ((b as f32) - (a as f32)) * t).round() as u8;
+        Rgb(m(self.0, other.0), m(self.1, other.1), m(self.2, other.2))
+    }
+
+    /// Adds a signed offset per channel, clamped.
+    pub fn tint(self, dr: i16, dg: i16, db: i16) -> Rgb {
+        let t = |c: u8, d: i16| (c as i16 + d).clamp(0, 255) as u8;
+        Rgb(t(self.0, dr), t(self.1, dg), t(self.2, db))
+    }
+}
+
+/// One rendered terminal cell.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct Cell {
+    pub ch: char,
+    pub fg: Rgb,
+    pub bg: Rgb,
+    pub bold: bool,
+    pub dim: bool,
+}
+
+impl Cell {
+    pub fn write(&self, buf: &mut Buffer, x: u16, y: u16) {
+        if x < buf.area.x || y < buf.area.y || x >= buf.area.right() || y >= buf.area.bottom() {
+            return;
+        }
+        let mut style = Style::default()
+            .fg(self.fg.to_color())
+            .bg(self.bg.to_color());
+        if self.bold {
+            style = style.add_modifier(Modifier::BOLD);
+        }
+        if self.dim {
+            style = style.add_modifier(Modifier::DIM);
+        }
+        buf[(x, y)].set_char(self.ch).set_style(style);
+    }
+}
+
+/// What the walker knows about a tile.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub enum Visibility {
+    Unseen,
+    Remembered,
+    Visible,
+}
+
+/// A connector under the tile and which way it leads from the current stratum.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct ConnDir {
+    pub kind: ConnectorKind,
+    pub up: bool,
+    pub down: bool,
+}
+
+/// Everything `tileset::cell` needs besides the tile itself.
+pub struct RenderCtx<'a> {
+    pub style: &'a StylePack,
+    pub theme: Option<Theme>,
+    pub stratum: StratumKind,
+    pub light: u8,
+    pub tick: u64,
+    pub pos: Pos,
+    pub vis: Visibility,
+    pub connector: Option<ConnDir>,
+    pub kind: Option<BuildingKind>,
+    /// Bits N=1, E=2, S=4, W=8: neighbours that connect to this tile (see `tileset::connects`).
+    pub wall_mask: u8,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn rgb_math() {
+        assert_eq!(Rgb(100, 200, 50).scale(0.5), Rgb(50, 100, 25));
+        assert_eq!(Rgb(100, 100, 100).scale(10.0), Rgb(255, 255, 255));
+        assert_eq!(Rgb(0, 0, 0).mix(Rgb(100, 200, 50), 0.5), Rgb(50, 100, 25));
+        assert_eq!(Rgb(10, 10, 10).tint(-20, 5, 300), Rgb(0, 15, 255));
+    }
+}