speed up some stuff indirectly used in bus locations to not be so terrible

sim/src/mechanics/driving.rs

@@ -771,6 +771,20 @@ impl DrivingSimState {
         result
     }
 
+    // This is about as expensive as get_draw_cars_on.
+    pub fn get_single_draw_car(
+        &self,
+        id: CarID,
+        now: Duration,
+        map: &Map,
+        transit: &TransitSimState,
+    ) -> Option<DrawCarInput> {
+        let car = self.cars.get(&id)?;
+        self.get_draw_cars_on(now, car.router.head(), map, transit)
+            .into_iter()
+            .find(|d| d.id == id)
+    }
+
     pub fn get_draw_cars_on(
         &self,
         now: Duration,

sim/src/mechanics/walking.rs

@@ -85,6 +85,15 @@ impl WalkingSimState {
         );
     }
 
+    pub fn get_draw_ped(
+        &self,
+        id: PedestrianID,
+        now: Duration,
+        map: &Map,
+    ) -> Option<DrawPedestrianInput> {
+        self.peds.get(&id).map(|p| p.get_draw_ped(now, map))
+    }
+
     pub fn get_all_draw_peds(&self, now: Duration, map: &Map) -> Vec<DrawPedestrianInput> {
         self.peds
             .values()

sim/src/sim.rs

@@ -288,13 +288,14 @@ impl GetDrawAgents for Sim {
     }
 
     fn get_draw_car(&self, id: CarID, map: &Map) -> Option<DrawCarInput> {
-        // TODO Faster
-        self.get_all_draw_cars(map).into_iter().find(|d| d.id == id)
+        self.parking.get_draw_car(id, map, &self.trips).or_else(|| {
+            self.driving
+                .get_single_draw_car(id, self.time, map, &self.transit)
+        })
     }
 
     fn get_draw_ped(&self, id: PedestrianID, map: &Map) -> Option<DrawPedestrianInput> {
-        // TODO Faster
-        self.get_all_draw_peds(map).into_iter().find(|d| d.id == id)
+        self.walking.get_draw_ped(id, self.time, map)
     }
 
     fn get_draw_cars(&self, on: Traversable, map: &Map) -> Vec<DrawCarInput> {