making peds leave the bus

docs/design.md

@@ -696,7 +696,6 @@ step 2: move interactive and testish spawning stuff to init() or similar, leavin
 		- i just physically want the code in a separate file. can we implement a trait in a second file?
 step 3: enhance the trip stuff to have a concept of hardcoded legs, and make it choose how to use a bus
 	- seed a trip using a bus
-	- wire up the transitions to board and deboard the bus
 	- test a basic bus scenario
 
 

docs/references.md

@@ -4,3 +4,7 @@
 
 - Seattle Times Traffic Lab
 - https://www.citylab.com/transportation/2018/08/is-it-time-to-rethink-what-a-bike-lane-is/568483/
+
+## Similar projects
+
+- Urban Footprint (https://news.ycombinator.com/item?id=17895739)

sim/src/sim.rs

@@ -178,8 +178,13 @@ impl Sim {
             );
         }
 
-        self.transit_state
+        self.transit_state.step(
-            .step(&mut events, &mut self.walking_state, &mut self.trips_state);
+            self.time,
+            &mut events,
+            &mut self.walking_state,
+            &mut self.trips_state,
+            &mut self.spawner,
+        );
 
         // TODO want to pass self as a lazy QueryCar trait, but intersection_state is mutably
         // borrowed :(

sim/src/spawn.rs

@@ -336,6 +336,23 @@ impl Spawner {
     }
 
     // Trip transitions
+    pub fn ped_finished_bus_ride(
+        &mut self,
+        at: Tick,
+        ped: PedestrianID,
+        stop: BusStop,
+        trips: &mut TripManager,
+    ) {
+        let (trip, walk_to) = trips.ped_finished_bus_ride(ped);
+        self.commands.push_back(Command::Walk(
+            at.next(),
+            trip,
+            ped,
+            SidewalkSpot::bus_stop(stop),
+            walk_to,
+        ));
+    }
+
     pub fn car_reached_parking_spot(
         &mut self,
         at: Tick,

sim/src/transit.rs

@@ -4,6 +4,7 @@ use driving::CarView;
 use events::Event;
 use map_model;
 use map_model::{BusStop, LaneID, Map};
+use spawn::Spawner;
 use std::collections::{BTreeMap, VecDeque};
 use trips::TripManager;
 use walking::WalkingSimState;
@@ -188,9 +189,11 @@ impl TransitSimState {
 
     pub fn step(
         &mut self,
+        now: Tick,
         events: &mut Vec<Event>,
         walking_sim: &mut WalkingSimState,
         trips: &mut TripManager,
+        spawner: &mut Spawner,
     ) {
         for b in self.buses.values_mut() {
             if let BusState::AtStop(stop_idx, _) = b.state {
@@ -214,10 +217,11 @@ impl TransitSimState {
                 // which is called by router! thats convoluted
                 let car = b.car;
                 b.passengers.retain(|p| {
-                    println!("TODO should {} leave bus {}?", p, car);
+                    if trips.should_ped_leave_bus(*p, &stop) {
-                    if false {
                         events.push(Event::PedLeavesBus(*p, car));
-                        // TODO call something on the spawner to join the walking sim again
+                        // TODO would be a little cleaner to return this info up to sim and have it
+                        // plumb through to spawner? not sure
+                        spawner.ped_finished_bus_ride(now, *p, stop.clone(), trips);
                         false
                     } else {
                         true

sim/src/trips.rs

@@ -82,14 +82,44 @@ impl TripManager {
             return false;
         }
 
-        // They're boarding!
-        self.active_trip_mode.remove(&AgentID::Pedestrian(ped));
         // Could assert that the first leg is walking to the right bus stop
         trip.legs.pop_front();
+        // Leave active_trip_mode as Pedestrian, since the transit sim tracks passengers as
+        // PedestrianIDs.
 
         true
     }
 
+    pub fn should_ped_leave_bus(&self, ped: PedestrianID, stop: &BusStop) -> bool {
+        let trip = &self.trips[self.active_trip_mode[&AgentID::Pedestrian(ped)].0];
+
+        match trip.legs[0] {
+            TripLeg::RideBus(_, ref until_stop) => stop == until_stop,
+            ref x => panic!("{} is on a bus stop, but first leg is {:?}", ped, x),
+        }
+    }
+
+    // Where to walk next?
+    pub fn ped_finished_bus_ride(&mut self, ped: PedestrianID) -> (TripID, SidewalkSpot) {
+        // The spawner will call agent_starting_trip_leg, so briefly remove the active PedestrianID.
+        let trip = &mut self.trips[self.active_trip_mode
+                                       .remove(&AgentID::Pedestrian(ped))
+                                       .unwrap()
+                                       .0];
+
+        match trip.legs.pop_front().unwrap() {
+            TripLeg::RideBus(_, _) => {}
+            x => panic!("First trip leg {:?} doesn't match ped_finished_bus_ride", x),
+        };
+        // TODO there are only some valid sequences of trips. it'd be neat to guarantee these are
+        // valid by construction with a fluent API.
+        let walk_to = match trip.legs[0] {
+            TripLeg::Walk(ref to) => to,
+            ref x => panic!("Next trip leg is {:?}, not walking", x),
+        };
+        (trip.id, walk_to.clone())
+    }
+
     // Creation from the interactive part of spawner
     pub fn new_trip(
         &mut self,