transporters

kiln-core/src/action.rs

@@ -99,10 +99,11 @@ pub enum Action {
     /// Open a scrollable text overlay. Pauses game ticks while shown; a choice
     /// selection dispatches [`Send`](Action::Send) to the source object.
     Scroll(Vec<ScrollLine>),
-    /// Teleport the source object to `(x, y)`. Blocked (with a logged error) if
-    /// the source is solid and the destination already has a solid occupant.
-    /// Zero time cost — multiple teleports may fire in one frame.
-    Teleport { x: i64, y: i64 },
+    /// Teleport object `target` to `(x, y)` (`target == -1` is the player).
+    /// Blocked (with a logged error) if that entity is solid and the destination
+    /// already has a *different* solid occupant. Zero time cost — multiple
+    /// teleports may fire in one frame.
+    Teleport { target: i64, x: i64, y: i64 },
     /// Shove the pushable chain starting at `(x, y)` one step in `dir` (acts on
     /// arbitrary cells, not the source object). Zero time cost.
     Push { x: i64, y: i64, dir: Direction },

kiln-core/src/archetype.rs

@@ -123,6 +123,17 @@ builtins! {
         behavior: Behavior { solid: true, opaque: true, pushable: Pushable::No, grab: false },
         script: include_str!("scripts/spinner.rhai"),
     },
+    // Solid, see-through (opaque: false), unpushable teleporters. Each direction's
+    // default glyph is the first frame of its animation loop (see transporter.rhai).
+    Transporter => [
+        "transporter_north" => g(94,  0x55, 0xFF, 0xFF),   // '^'
+        "transporter_south" => g(118, 0x55, 0xFF, 0xFF),   // 'v'
+        "transporter_east"  => g(41,  0x55, 0xFF, 0xFF),   // ')'
+        "transporter_west"  => g(40,  0x55, 0xFF, 0xFF),   // '('
+    ] {
+        behavior: Behavior { solid: true, opaque: false, pushable: Pushable::No, grab: false },
+        script: include_str!("scripts/transporter.rhai"),
+    },
     Key => [ // TODO these should refer to the key colors in Keyring
         "key_blue"   => KeyType::Blue.glyph(),
         "key_green"  => KeyType::Green.glyph(),

kiln-core/src/game.rs

@@ -282,24 +282,56 @@ impl GameState {
                             choice: None,
                         });
                     }
-                    Action::Teleport { x, y } => {
+                    Action::Teleport { target, x, y } => {
                         if !board.in_bounds((x, y)) {
-                            logs.push(LogLine::error(format!("teleport({x},{y}): out of bounds")));
-                        } else {
+                            logs.push(LogLine::error(format!(
+                                "teleport({target},{x},{y}): out of bounds"
+                            )));
+                        } else if target == -1 {
+                            // Move the player. A solid *other than the player itself*
+                            // blocks the destination.
                             let (ux, uy) = (x as usize, y as usize);
-                            let source_solid = board
-                                .objects
-                                .get(&ba.source)
-                                .map(|o| o.solid)
-                                .unwrap_or(false);
-                            if source_solid && board.solid_at(ux, uy).is_some() {
+                            let blocked = matches!(
+                                board.solid_at(ux, uy),
+                                Some(s) if !s.player()
+                            );
+                            if blocked {
                                 logs.push(LogLine::error(format!(
-                                    "teleport({x},{y}): destination is solid"
+                                    "teleport(player,{x},{y}): destination is solid"
                                 )));
-                            } else if let Some(obj) = board.objects.get_mut(&ba.source) {
-                                obj.x = ux;
-                                obj.y = uy;
+                            } else {
+                                board.player.x = ux as i64;
+                                board.player.y = uy as i64;
                             }
+                        } else if let Ok(tid) = ObjectId::try_from(target) {
+                            // Move object `tid` to (x, y). A solid destination blocks
+                            // a solid mover, unless the occupant is that same object.
+                            let (ux, uy) = (x as usize, y as usize);
+                            match board.objects.get(&tid) {
+                                None => logs.push(LogLine::error(format!(
+                                    "teleport({target},{x},{y}): no such object"
+                                ))),
+                                Some(obj) => {
+                                    let source_solid = obj.solid;
+                                    let blocked = source_solid
+                                        && matches!(
+                                            board.solid_at(ux, uy),
+                                            Some(s) if s.object_id() != Some(tid)
+                                        );
+                                    if blocked {
+                                        logs.push(LogLine::error(format!(
+                                            "teleport({target},{x},{y}): destination is solid"
+                                        )));
+                                    } else if let Some(obj) = board.objects.get_mut(&tid) {
+                                        obj.x = ux;
+                                        obj.y = uy;
+                                    }
+                                }
+                            }
+                        } else {
+                            logs.push(LogLine::error(format!(
+                                "teleport({target},{x},{y}): invalid target id"
+                            )));
                         }
                     }
                     // push() self-checks can_push, so an in-bounds guard is all we add.

kiln-core/src/script.rs

@@ -27,7 +27,7 @@
 //!
 //! `move(dir)`, `delay(secs)`, `now()`, `set_tile(n)`, `log(msg)`, `say(msg)`,
 //! `set_fg(fg)`, `set_bg(bg)`, `set_color(fg, bg)`, `set_tag(target, tag, present)`,
-//! `send(target_id, fn_name [, arg])`, `teleport(x, y)`, `push(x, y, dir)`,
+//! `send(target_id, fn_name [, arg])`, `teleport(id, x, y)`, `push(x, y, dir)`,
 //! `shift([[x, y], …])`, `alter_gems(n)`, `alter_health(dh)`, `set_key(color, present)`, `die()`
 
 use crate::action::{Action, BoardAction, ScrollLine, SendArg, MOVE_COST};
@@ -554,12 +554,13 @@ fn register_write_api(engine: &mut Engine, board: BoardRef) {
         },
     );
 
-    // teleport(x, y): move the calling object to an arbitrary cell. Zero time cost.
-    // Blocked (with an error logged at resolve time) if the object is solid and the
-    // destination already has a solid occupant.
+    // teleport(target, x, y): move object `target` to an arbitrary cell (pass your
+    // own `me.id` to move yourself; `target == -1` moves the player). Zero time
+    // cost. Blocked (with an error logged at resolve time) if that entity is solid
+    // and the destination already holds a different solid occupant.
     let b = board.clone();
-    engine.register_fn("teleport", move |ctx: NativeCallContext, x: i64, y: i64| {
-        emit(&b, source_of(&ctx), Action::Teleport { x, y });
+    engine.register_fn("teleport", move |ctx: NativeCallContext, target: i64, x: i64, y: i64| {
+        emit(&b, source_of(&ctx), Action::Teleport { target, x, y });
     });
 
     // push(x, y, dir): shove the pushable chain at (x, y) one step in dir. Acts on

kiln-core/src/scripts/transporter.rhai

@@ -0,0 +1,105 @@
+// Built-in script for the `transporter_*` archetypes (see archetype.rs).
+//
+// A transporter is a solid, see-through, unpushable machine that teleports
+// whatever bumps into it from its facing side. It animates through a 4-frame
+// loop (500 ms/frame) and, on a front bump, moves the bumper either to the cell
+// just past it or — if that's blocked — out of the nearest opposite-facing
+// transporter further along its axis (skipping any whose entrance is blocked).
+//
+// The direction is not baked into this source: every transporter shares one
+// compiled copy and reads its `BUILTIN_transporter_<dir>` tag. The world is
+// reached through the global `Board`/`Player` constants; `teleport(id, x, y)`
+// moves an arbitrary entity (`-1` is the player).
+
+// This transporter's facing unit vector, from its direction tag.
+fn facing(me) {
+    if me.has_tag("BUILTIN_transporter_north") { [0, -1] }
+    else if me.has_tag("BUILTIN_transporter_south") { [0, 1] }
+    else if me.has_tag("BUILTIN_transporter_east") { [1, 0] }
+    else { [-1, 0] }
+}
+
+// The tag of the opposite-facing transporter this one pairs with.
+fn opposite_tag(me) {
+    if me.has_tag("BUILTIN_transporter_north") { "BUILTIN_transporter_south" }
+    else if me.has_tag("BUILTIN_transporter_south") { "BUILTIN_transporter_north" }
+    else if me.has_tag("BUILTIN_transporter_east") { "BUILTIN_transporter_west" }
+    else { "BUILTIN_transporter_east" }
+}
+
+// The 4-frame animation loop for this direction (CP437 tile codes).
+fn frames(me) {
+    if me.has_tag("BUILTIN_transporter_north") { [94, 45, 94, 126] }   // ^ - ^ ~
+    else if me.has_tag("BUILTIN_transporter_south") { [118, 95, 118, 45] } // v _ v -
+    else if me.has_tag("BUILTIN_transporter_east") { [41, 124, 41, 62] }   // ) | ) >
+    else { [40, 124, 40, 60] }                                        // ( | ( <
+}
+
+fn tick(me, dt) {
+    // Advance one animation frame every 0.5s, like the spinner: frame state lives
+    // in the board Registry (script scope resets each tick), keyed per instance.
+    if me.waiting { return; }
+    let fs = frames(me);
+    let fkey = `xport_${me.id}`;
+    let f = Board.registry.get_or(fkey, 0);
+    set_tile(fs[f % 4]);
+    Board.registry.set(fkey, (f + 1) % 4);
+    me.delay(0.15);
+}
+
+fn bump(me, id) {
+    let d = facing(me);
+    let dx = d[0];
+    let dy = d[1];
+
+    // Only transport things that hit us from the front — the entrance cell at
+    // (me - d). A bump from any other side does nothing.
+    let bx;
+    let by;
+    if id == -1 {
+        bx = Player.x;
+        by = Player.y;
+    } else {
+        let o = Board.get(id);
+        if o == () { return; }
+        bx = o.x;
+        by = o.y;
+    }
+    if bx != me.x - dx || by != me.y - dy { return; }
+
+    // 1. The cell just past us (the opposite side): if nothing solid is there,
+    //    drop the bumper onto it.
+    let fx = me.x + dx;
+    let fy = me.y + dy;
+    if Board.passable(fx, fy) {
+        teleport(id, fx, fy); now();
+        return;
+    }
+
+    // 2. Otherwise scan along our axis for the nearest opposite-facing transporter
+    //    whose entrance (the cell just before it) is free, and drop the bumper
+    //    there. A blocked pair is skipped; give up at the board edge.
+    let opp = Board.tagged(opposite_tag(me));
+    let cx = fx;
+    let cy = fy;
+    loop {
+        cx += dx;
+        cy += dy;
+        if cx < 0 || cy < 0 || cx >= Board.width || cy >= Board.height {
+            return;
+        }
+        // Is one of the opposite transporters sitting at (cx, cy)?
+        let here = false;
+        for o in opp {
+            if o.x == cx && o.y == cy { here = true; }
+        }
+        if here {
+            let ex = cx + dx;
+            let ey = cy + dy;
+            if Board.passable(ex, ey) {
+                teleport(id, ex, ey); now();
+                return;
+            }
+        }
+    }
+}

kiln-core/src/tests/map_file/mod.rs

@@ -6,6 +6,7 @@ mod portal_placement;
 mod pushers;
 mod round_trip;
 mod spinners;
+mod transporters;
 
 use crate::board::Board;
 use crate::map_file::MapFile;

kiln-core/src/tests/map_file/transporters.rs

@@ -0,0 +1,115 @@
+//! Transporters are scripted objects (the `transporter_*` archetypes expand into
+//! objects carrying the embedded `transporter.rhai` plus a
+//! `BUILTIN_transporter_<dir>` tag). Bumping one from its facing side teleports
+//! the bumper past it, or out of a paired opposite-facing transporter.
+
+use super::{layer, load_board, map};
+use crate::game::GameState;
+use crate::map_file::MapFile;
+use crate::utils::Direction;
+use std::time::Duration;
+
+#[test]
+fn transporter_loads_as_a_tagged_scripted_solid_object() {
+    let board = load_board(&map(
+        3,
+        1,
+        &[layer(
+            "@T ",
+            &[("@", "kind = \"player\""), ("T", "kind = \"transporter_east\"")],
+        )],
+    ));
+    let (_, obj) = board
+        .objects
+        .iter()
+        .find(|(_, o)| o.tags.contains("BUILTIN_transporter_east"))
+        .expect("transporter object");
+    assert_eq!((obj.x, obj.y), (1, 0));
+    assert!(obj.builtin_script.is_some(), "carries the embedded script");
+    assert!(obj.solid, "transporter is solid");
+    assert!(!obj.opaque, "transporter is see-through");
+    assert!(!obj.pushable, "transporter cannot be pushed");
+}
+
+#[test]
+fn bumping_a_transporter_drops_you_on_its_far_side() {
+    // Player at (0,0), an east transporter at (1,0), and a free cell at (2,0).
+    let board = load_board(&map(
+        3,
+        1,
+        &[layer(
+            "@T ",
+            &[("@", "kind = \"player\""), ("T", "kind = \"transporter_east\"")],
+        )],
+    ));
+    let mut game = GameState::new(board);
+    game.run_init();
+
+    // Walk east into the transporter: it's solid so the player doesn't step onto
+    // it, but the bump queues a teleport that the next tick applies.
+    game.try_move(Direction::East);
+    game.tick(Duration::from_secs_f64(0.1));
+
+    let b = game.board();
+    assert_eq!((b.player.x, b.player.y), (2, 0), "transported past the transporter");
+}
+
+#[test]
+fn a_blocked_far_side_transports_out_of_the_paired_transporter() {
+    // Player, east transporter, a wall blocking its far side, the free entrance
+    // cell, then the paired west transporter. The player should pop out at the
+    // west transporter's entrance (the cell just before it), across the wall.
+    let board = load_board(&map(
+        6,
+        1,
+        &[layer(
+            "@T# W ",
+            &[
+                ("@", "kind = \"player\""),
+                ("T", "kind = \"transporter_east\""),
+                ("#", "kind = \"wall\", tile = 35, fg = \"#808080\", bg = \"#606060\""),
+                ("W", "kind = \"transporter_west\""),
+            ],
+        )],
+    ));
+    let mut game = GameState::new(board);
+    game.run_init();
+
+    game.try_move(Direction::East);
+    game.tick(Duration::from_secs_f64(0.1));
+
+    let b = game.board();
+    assert_eq!(
+        (b.player.x, b.player.y),
+        (3, 0),
+        "transported to the paired transporter's entrance",
+    );
+}
+
+#[test]
+fn transporter_round_trips_to_its_keyword() {
+    let board = load_board(&map(
+        3,
+        1,
+        &[layer(
+            "@T ",
+            &[("@", "kind = \"player\""), ("T", "kind = \"transporter_east\"")],
+        )],
+    ));
+    // Save collapses the expanded object back into the `transporter_east` keyword.
+    let toml_out = toml::to_string_pretty(&MapFile::from(&board)).unwrap();
+    assert!(
+        toml_out.contains("transporter_east"),
+        "transporter should save as its archetype keyword, got:\n{toml_out}"
+    );
+
+    // Reload: it is a working transporter object again.
+    let board2 = load_board(&toml_out);
+    assert!(
+        board2
+            .objects
+            .values()
+            .any(|o| o.tags.contains("BUILTIN_transporter_east") && o.builtin_script.is_some()),
+        "reloads as a tagged transporter object",
+    );
+}