ludic.npc (18.2): a person a crowd moves

npc_set_crowd hands a person to a crowd. Its walk no longer steps or asks the way: its want is goal_x / goal_z / goal_speed (0 when it is not walking). npc_moved hands back the crowd's place: position, ground, heading from velocity, gait. Arrival, the act and the give-up after twenty seconds without progress are unchanged. Nothing allocates. npc 16/16.

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

packages/ludic.npc/defs.ludic

@@ -52,6 +52,10 @@ export property NpcPerson {
   wtx: float = 0.0             # the target that corner was asked for: a new target asks again
   wtz: float = 0.0
   way_t: float = 0.0           # seconds until it asks the way again
+  crowd: bool = false          # walked by the world's crowd (phase 18): it decides, the crowd moves it
+  goal_x: float = 0.0          # where it walks this tick and how fast (0 standing): what a crowd is handed
+  goal_z: float = 0.0
+  goal_speed: float = 0.0
   detours: int = 0
   fails: int = 0
   stall: float = 0.0           # seconds walking without moving

packages/ludic.npc/tests/way_test.ludic

@@ -81,4 +81,24 @@ program NpcWayTest {
     let fs = q_drain(npc_facts(npc_st))
     for i in 0 .. len(fs) { expect(fs[i].what != NPC_F_STUCK) }
   }
+
+  test "a crowd walker says where and how fast, is moved by hand to its target, and begins there" (npc_st: mut NpcState, npc_tests_fake_st: mut NpcTestsFakeState, way_test_st: WayTestState) {
+    fk_setup(npc_st, npc_tests_fake_st)
+    npc_tests_fake_st.fk_want = 1
+    let p = npc_spawn(npc_st, NPCK_HIKER)
+    npc_set_at(p, 0.0, 0.0)
+    npc_set_crowd(p, true)
+    npc_go(npc_st, p, 38.0, -25.0, NPCA_SIT, 30.0)
+    for k in 0 .. 60 { npc_tick(npc_st, 0.05) }
+    expect_eq(p.x, 0.0)
+    expect_eq(p.z, 0.0)
+    expect_eq(p.goal_x, 38.0)
+    expect_eq(p.goal_z, -25.0)
+    expect(p.goal_speed > 0.5)
+    expect_eq(way_test_st.asked, 0)
+    for k in 1 .. 101 { npc_moved(p, 0.38 * float(k), -0.25 * float(k), 1.0, -0.66) }
+    npc_tick(npc_st, 0.05)
+    expect_eq(p.act, NPCA_SIT)
+    expect(p.phase > 100.0)
+  }
 }

packages/ludic.npc/tick.ludic

@@ -7,6 +7,7 @@ export function npc_tick(npc_st: mut NpcState, dt: float) -> void {
   for i in 0 .. len(npc_st.np_walkers) {
     let p = npc_st.np_walkers[i]
     if not p.active or np_leaves(npc_st, p) { continue }
+    p.goal_speed = 0.0
     if p.act == NPCA_WALK { npc_walk(npc_st, p, dt) } else { npc_act(npc_st, p, dt) }
     npc_notice(npc_st, p)
   }

packages/ludic.npc/walk.ludic

@@ -14,7 +14,7 @@ export function npc_walk(npc_st: mut NpcState, p: NpcPerson, dt: float) -> void
     np_arrive(npc_st, p)
     return
   }
-  if not p.via_on {
+  if not p.via_on and not p.crowd {
     np_way(p, dt)
     gx = p.wx
     gz = p.wz
@@ -33,6 +33,10 @@ export function npc_walk(npc_st: mut NpcState, p: NpcPerson, dt: float) -> void
   var sp = p.speed
   if sp < 0.1 { sp = 1.2 }
   if p.stalk { sp = Math.min(sp, 0.7) }
+  if p.crowd {
+    np_crowd_want(p, sp)
+    return
+  }
   let want = Math.atan2(-dx, -dz)
   let r = 3.0 * dt
   p.yaw = p.yaw + Math.clamp(npc_wrap(want - p.yaw), -r, r)

packages/ludic.npc/way.ludic

@@ -56,3 +56,21 @@ function np_stuck(npc_st: mut NpcState, p: NpcPerson) -> void {
     npc_plan(npc_st, p)
   }
 }
+
+# the crowd's side (phase 18): a crowd walker says where it is going and how fast, and is handed
+# back where the crowd put it; nothing allocates, since this runs for every walker every frame
+function np_crowd_want(p: NpcPerson, speed: float) -> void {
+  p.goal_x = p.tx
+  p.goal_z = p.tz
+  p.goal_speed = speed
+}
+export function npc_set_crowd(p: NpcPerson, on: bool) -> void { p.crowd = on }
+export function npc_moved(p: NpcPerson, x: float, z: float, vx: float, vz: float) -> void {
+  let dx = x - p.x
+  let dz = z - p.z
+  p.x = x
+  p.z = z
+  p.y = NpcWorld.ground(x, z)
+  if vx * vx + vz * vz > 0.01 { p.yaw = Math.atan2(-vx, -vz) }
+  p.phase = p.phase + Math.sqrt(dx * dx + dz * dz) * 2.6
+}