vehicles: a boat nobody rows is moored where it was called or left - its hull put back on the mooring (home_x, home_z, home_yaw) whenever it strays, and no wind on it; the wind drifts only a rowed boat

A called boat and one got out of drifted across the lake on the wind (the user's play of the bundle).
The tests hold a boat at its berth in a full wind for eight seconds, and one dropped out on the lake
where it was left.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/ludic.vehicles/README.md

@@ -26,8 +26,9 @@ through the game).
 - **A boat is a body in the game's physics** (`VehicleHull`, phase 16; a buoyant Jolt hull in Maroon
   Lake). The package rows it - the stick forward and back is a stroke along the bow, left and right
   the oars pulled against each other - and reads back where the hull is and how fast it goes. The
-  water floats it, the wind (`VehicleWorld.wind`) drifts every boat, ridden or not, and the lake bed
+  water floats it, the wind (`VehicleWorld.wind`) drifts a rowed boat, and the lake bed stops it at
-  stops it at the shore; the swell at the sail limit takes the outward share of a stroke.
+  the shore. A boat nobody rows is moored where it was called or left (`home_x`, `home_z`,
+  `home_yaw`): its hull is put back there whenever it strays, so it never crosses the lake alone; the swell at the sail limit takes the outward share of a stroke.
 - **A horse walks on legs in the game's physics** (`VehicleLegs`; a Jolt walker in Maroon Lake). The
   package decides its pace - a walk, a canter on stamina, hay for every metre - and never steps it
   into water; the legs meet the ground, its steps and slopes, and whatever stands in its way. What
@@ -74,7 +75,7 @@ export port VehicleRider {
 | `vehicle_mount(v) -> bool`, `vehicle_dismount() -> bool`, `vehicle_drop()` | on and off |
 | `vehicle_update(ix, iz, run, dt)` | a frame of riding from the rider's stick (bind it where the body hands its stick over) |
 | `vehicle_own(v)`, `vehicle_feed(v, hay)`, `vehicle_follow(v, x, y, z, yaw)`, `vehicles_release(pid)`, `vehicle_restore(kind, owned, food)` | hiring, hay, a tied horse's wandering, a player leaving, a saved word |
-| `vehicles_tick(dt)` | every boat's hull read back and pushed by the wind (the game calls it where the world is run) |
+| `vehicles_tick(dt)` | every boat's hull read back: a rowed one pushed by the wind, one nobody rows held at its mooring (the game calls it where the world is run) |
 | `vehicle_facts() -> Queue<VehicleFact>` | `{ what, nid, kind, owner, x, z, v }`: `VEHICLE_MOUNTED`, `_DISMOUNTED`, `_NO_LANDING`, `_MOVED` (v: metres), `_SWELL` (every 14 s), `_HUNGRY`, `_FED` |
 | `vehicles_reset()`, `vehicles_system() -> System` | `"vehicles"`: this player's own saved by kind (hired, hay) - where they lie is not saved |
 

packages/ludic.vehicles/call.ludic

@@ -39,8 +39,14 @@ function ve_put(v: Vehicle, x: float, z: float) -> void {
   v.z = z
   v.speed = 0.0
   if v.kind == VEHICLE_BOAT { v.y = VehicleWorld.water(x, z) + 0.02 } else { v.y = VehicleWorld.ground(x, z) }
-  v.home_x = x
+  ve_moor(v)
-  v.home_z = z
+}
+
+# a boat nobody rows holds here (vehicles_tick); a horse is tied here
+function ve_moor(v: Vehicle) -> void {
+  v.home_x = v.x
+  v.home_z = v.z
+  v.home_yaw = v.yaw
 }
 
 # Bring player pid's boat or horse to place k. False when the place is somebody else's, or it is
@@ -59,8 +65,8 @@ export function vehicle_call_for(vehicles_st: VehiclesState, pid: int, kind: int
     return true
   }
   if v.rider >= 0 { return false }
-  ve_put(v, vehicle_place_x(vehicles_st, kind, k), vehicle_place_z(vehicles_st, kind, k))
   v.yaw = yaw
+  ve_put(v, vehicle_place_x(vehicles_st, kind, k), vehicle_place_z(vehicles_st, kind, k))
   ve_settle(v)
   VehicleWorld.placed(v)
   return true

packages/ludic.vehicles/kinds.ludic

@@ -17,8 +17,9 @@ export property Vehicle {
   owned: bool = false     # hired or rented for the trip
   owner: int = 0          # the player it belongs to (0: this machine's)
   rider: int = -1         # the player on it, -1 nobody
-  home_x: float = 0.0     # a horse is tied where its home is
+  home_x: float = 0.0     # a horse is tied where its home is; a boat nobody rows is moored there
   home_z: float = 0.0
+  home_yaw: float = 0.0   # and a moored boat faces as it was left
   ent: int = -1           # its handle in the table
   tab: Table<Vehicle> = null
 }

packages/ludic.vehicles/mount.ludic

@@ -28,6 +28,7 @@ export function vehicle_dismount(vehicles_st: mut VehiclesState) -> bool {
       return false
     }
     VehicleRider.step_off(VehicleRider.safe_x(), VehicleRider.safe_z())
+    ve_moor(v)
   } else {
     let wx = v.x + Math.cos(v.yaw) * 1.2
     let wz = v.z - Math.sin(v.yaw) * 1.2
@@ -49,6 +50,7 @@ export function vehicle_drop(vehicles_st: mut VehiclesState) -> void {
   if vehicles_st.ve_cur != null {
     vehicles_st.ve_cur.rider = -1
     vehicles_st.ve_cur.speed = 0.0
+    if vehicles_st.ve_cur.kind == VEHICLE_BOAT { ve_moor(vehicles_st.ve_cur) }
   }
   vehicles_st.ve_cur = null
 }

packages/ludic.vehicles/ride.ludic

@@ -51,19 +51,35 @@ function ve_swell(vehicles_st: mut VehiclesState, v: Vehicle, iz: float, dt: flo
   return take
 }
 
-# every boat: its hull read back, and the wind pushing it across the lake, ridden or not
+# every boat: a rowed one pushed by the wind across the lake; one nobody rows moored where it was
+# called or left, its hull read back and held there
 export function vehicles_tick(vehicles_st: VehiclesState, dt: float) -> void {
   let l = ve_all(vehicles_st)
   let w = VehicleWorld.wind() * VE_WIND
   let wy = VehicleWorld.wind_yaw()
   for i in 0 .. len(l) {
     let v = l[i]
-    if v.kind == VEHICLE_BOAT {
+    if v.kind != VEHICLE_BOAT { continue }
+    if v.rider >= 0 {
       if w > 0.0 { VehicleHull.drift(v.nid, -Math.sin(wy) * w, -Math.cos(wy) * w) }
-      if v.rider < 0 {
+      continue
-        ve_hull_read(v)
-        VehicleWorld.placed(v)
-      }
     }
+    ve_hull_read(v)
+    ve_hold(v)
+    VehicleWorld.placed(v)
   }
 }
+
+# a moored hull that has moved off its mooring (a knock, the swell) is put back on it, at rest
+function ve_hold(v: Vehicle) -> void {
+  let dx = v.x - v.home_x
+  let dz = v.z - v.home_z
+  let dyaw = Math.abs(Math.atan2(Math.sin(v.yaw - v.home_yaw), Math.cos(v.yaw - v.home_yaw)))
+  if dx * dx + dz * dz < 0.0004 and dyaw < 0.01 and Math.abs(v.speed) < 0.01 { return }
+  v.x = v.home_x
+  v.z = v.home_z
+  v.yaw = v.home_yaw
+  v.y = VehicleWorld.water(v.x, v.z) + 0.02
+  v.speed = 0.0
+  VehicleHull.put(v.nid, v.x, v.y, v.z, v.yaw)
+}

packages/ludic.vehicles/tests/vehicles_test.ludic

@@ -309,6 +309,31 @@ program VehiclesTest {
     expect(b.z < z0 - 0.2)
   }
 
+  test "a boat nobody rows holds its berth in a wind, and one left out on the lake holds where it was left" (physics_st: mut PhysicsState, vehicles_st: mut VehiclesState, vehicles_test_st: mut VehiclesTestState) {
+    fresh(vehicles_st, vehicles_test_st)
+    vehicle_call_for(vehicles_st, 0, VEHICLE_BOAT, 0)
+    let b = vehicle_find(vehicles_st, VEHICLE_BOAT)
+    let bx = b.x
+    let bz = b.z
+    vehicles_test_st.wind = 1.0
+    ride(physics_st, vehicles_st, 0.0, 0.0, false, 8.0)
+    expect_near(b.x, bx, 0.2)
+    expect_near(b.z, bz, 0.2)
+    expect(vehicle_in_place(vehicles_st, VEHICLE_BOAT, 0) != null)
+    vehicles_test_st.wind = 0.0
+    vehicle_mount(vehicles_st, b)
+    ride(physics_st, vehicles_st, 0.0, 1.0, false, 4.0)
+    vehicle_drop(vehicles_st)
+    let lx = b.x
+    let lz = b.z
+    expect(lx > bx + 4.0)
+    vehicles_test_st.wind = 1.0
+    ride(physics_st, vehicles_st, 0.0, 0.0, false, 8.0)
+    expect_near(b.x, lx, 0.2)
+    expect_near(b.z, lz, 0.2)
+    expect(Math.abs(b.speed) < 0.05)
+  }
+
   function char_turn(a: float) -> float {
     var d = a
     while d > 3.14159265 { d -= 6.2831853 }