animate pedestrian feet smoothly regardless of sim speed

editor/src/render/pedestrian.rs

@@ -1,7 +1,7 @@
 use crate::helpers::{ColorScheme, ID};
 use crate::render::{should_draw_blinkers, DrawCtx, DrawOptions, Renderable};
 use ezgui::{Color, Drawable, GfxCtx, Prerender};
-use geom::{Circle, Distance, Duration, PolyLine, Polygon};
+use geom::{Circle, Distance, PolyLine, Polygon};
 use map_model::{Map, LANE_THICKNESS};
 use sim::{DrawPedestrianInput, PedestrianID};
 
@@ -17,7 +17,7 @@ pub struct DrawPedestrian {
 impl DrawPedestrian {
     pub fn new(
         input: DrawPedestrianInput,
-        time: Duration,
+        step_count: usize,
         map: &Map,
         prerender: &Prerender,
         cs: &ColorScheme,
@@ -59,11 +59,12 @@ impl DrawPedestrian {
         );
         let foot_color = cs.get_def("pedestrian foot", Color::BLACK);
         // Jitter based on ID so we don't all walk synchronized.
-        let remainder = if input.id.0 % 2 == 0 { 0.0 } else { 1.0 };
+        let jitter = input.id.0 % 2 == 0;
+        let remainder = step_count % 6;
         if input.waiting_for_turn.is_some() {
             draw_default.push((foot_color, left_foot.to_polygon()));
             draw_default.push((foot_color, right_foot.to_polygon()));
-        } else if time.inner_seconds() * 10.0 % 2.0 == remainder {
+        } else if (jitter && remainder < 3) || (!jitter && remainder >= 3) {
             draw_default.push((foot_color, left_foot.to_polygon()));
             draw_default.push((
                 foot_color,

editor/src/sandbox/time_travel.rs

@@ -124,6 +124,10 @@ impl GetDrawAgents for TimeTravel {
         self.state_per_time[self.current_idx.unwrap()].time
     }
 
+    fn step_count(&self) -> usize {
+        self.current_idx.unwrap()
+    }
+
     fn get_draw_car(&self, id: CarID, _map: &Map) -> Option<DrawCarInput> {
         self.get_current_state().cars.get(&id).cloned()
     }

editor/src/ui.rs

@@ -285,6 +285,7 @@ impl UI {
         // Expand all of the Traversables into agents, populating the cache if needed.
         {
             let time = source.time();
+            let step_count = source.step_count();
 
             for on in &agents_on {
                 if !agents.has(time, *on) {
@@ -294,7 +295,7 @@ impl UI {
                     }
                     for p in source.get_draw_peds(*on, map).into_iter() {
                         list.push(Box::new(DrawPedestrian::new(
-                            p, time, map, prerender, &self.cs,
+                            p, step_count, map, prerender, &self.cs,
                         )));
                     }
                     agents.put(time, *on, list);

sim/src/render.rs

@@ -39,6 +39,8 @@ pub enum CarStatus {
 // otherwise? except we don't know what to calculate. maybe cache it?
 pub trait GetDrawAgents {
     fn time(&self) -> Duration;
+    // Every time the time changes, this should increase. For smoothly animating stuff.
+    fn step_count(&self) -> usize;
     fn get_draw_car(&self, id: CarID, map: &Map) -> Option<DrawCarInput>;
     fn get_draw_ped(&self, id: PedestrianID, map: &Map) -> Option<DrawPedestrianInput>;
     fn get_draw_cars(&self, on: Traversable, map: &Map) -> Vec<DrawCarInput>;

sim/src/sim.rs

@@ -39,6 +39,8 @@ pub struct Sim {
     // Some tests deliberately set different scenario names for comparisons.
     #[derivative(PartialEq = "ignore")]
     run_name: String,
+    #[derivative(PartialEq = "ignore")]
+    step_count: usize,
 
     // Lazily computed.
     #[derivative(PartialEq = "ignore")]
@@ -75,6 +77,7 @@ impl Sim {
             // TODO
             edits_name: "no_edits".to_string(),
             run_name,
+            step_count: 0,
             stats: None,
             events_since_last_step: Vec::new(),
         }
@@ -232,6 +235,10 @@ impl GetDrawAgents for Sim {
         self.time
     }
 
+    fn step_count(&self) -> usize {
+        self.step_count
+    }
+
     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)
@@ -277,6 +284,7 @@ impl Sim {
 // Running
 impl Sim {
     pub fn step(&mut self, map: &Map, dt: Duration) {
+        self.step_count += 1;
         if !self.spawner.is_done() {
             panic!("Forgot to call spawn_all_trips");
         }