first make a DirectedRoad ID, finally

docs/design/notes/discrete_sim.md

@@ -183,6 +183,8 @@ How could lane-changing work?
 	- one (usually turn) lane backfilling affects all
 - later: queue per lane. turn becomes lane->road
 	- the LCing itself doesnt really happen, merging has to happen upstream
+	- the only place this is really weird is when there are multiple turn lanes from src to dst
+	- or when two incoming roads could turn into different lanes of a road
 - actual LCing during freeflow/queueing time could make sense
 
 Now the interesting part... drawing!

editor/src/plugins/view/show_associated.rs

@@ -2,7 +2,7 @@ use crate::objects::{DrawCtx, ID};
 use crate::plugins::{AmbientPlugin, PluginCtx};
 use crate::render::ExtraShapeID;
 use ezgui::Color;
-use map_model::{BuildingID, IntersectionID, RoadID};
+use map_model::{BuildingID, DirectedRoadID, IntersectionID};
 use sim::{AgentID, CarID};
 use std::collections::HashSet;
 
@@ -10,7 +10,7 @@ pub enum ShowAssociatedState {
     Inactive,
     BuildingSelected(BuildingID, HashSet<CarID>),
     CarSelected(CarID, Option<BuildingID>),
-    ShapeSelected(ExtraShapeID, Option<(RoadID, bool)>),
+    ShapeSelected(ExtraShapeID, Option<DirectedRoadID>),
     IntersectionSelected(IntersectionID, HashSet<AgentID>),
 }
 

editor/src/render/extra_shape.rs

@@ -3,7 +3,7 @@ use crate::render::{RenderOptions, Renderable, EXTRA_SHAPE_POINT_RADIUS, EXTRA_S
 use ezgui::{Color, GfxCtx};
 use geom::{Bounds, Circle, Distance, FindClosest, GPSBounds, PolyLine, Polygon, Pt2D};
 use kml::ExtraShape;
-use map_model::{Map, RoadID, LANE_THICKNESS};
+use map_model::{DirectedRoadID, Map, LANE_THICKNESS};
 use std::collections::BTreeMap;
 use std::fmt;
 
@@ -25,7 +25,7 @@ pub struct DrawExtraShape {
     pub id: ExtraShapeID,
     shape: Shape,
     pub attributes: BTreeMap<String, String>,
-    pub road: Option<(RoadID, bool)>,
+    pub road: Option<DirectedRoadID>,
 }
 
 impl DrawExtraShape {
@@ -33,7 +33,7 @@ impl DrawExtraShape {
         id: ExtraShapeID,
         s: ExtraShape,
         gps_bounds: &GPSBounds,
-        closest: &FindClosest<(RoadID, bool)>,
+        closest: &FindClosest<DirectedRoadID>,
     ) -> Option<DrawExtraShape> {
         let mut pts: Vec<Pt2D> = Vec::new();
         for pt in s.points.into_iter() {

editor/src/render/map.rs

@@ -16,8 +16,8 @@ use abstutil::Timer;
 use ezgui::{Color, Drawable, Prerender};
 use geom::{Bounds, FindClosest, Polygon};
 use map_model::{
-    AreaID, BuildingID, BusStopID, IntersectionID, Lane, LaneID, Map, ParcelID, RoadID,
-    Traversable, Turn, TurnID, LANE_THICKNESS,
+    AreaID, BuildingID, BusStopID, DirectedRoadID, IntersectionID, Lane, LaneID, Map, ParcelID,
+    RoadID, Traversable, Turn, TurnID, LANE_THICKNESS,
 };
 use sim::Tick;
 use std::borrow::Borrow;
@@ -156,15 +156,14 @@ impl DrawMap {
                 shapes.shapes
             };
 
-            // Match shapes with the nearest road + direction (true for forwards)
-            let mut closest: FindClosest<(RoadID, bool)> = FindClosest::new(&map.get_bounds());
+            let mut closest: FindClosest<DirectedRoadID> = FindClosest::new(&map.get_bounds());
             for r in map.all_roads().iter() {
                 closest.add(
-                    (r.id, true),
+                    r.id.forwards(),
                     &r.center_pts.shift_right(LANE_THICKNESS).get(timer),
                 );
                 closest.add(
-                    (r.id, false),
+                    r.id.backwards(),
                     &r.center_pts.shift_left(LANE_THICKNESS).get(timer),
                 );
             }

map_model/src/lib.rs

@@ -27,7 +27,7 @@ pub use crate::map::Map;
 pub use crate::neighborhood::{Neighborhood, NeighborhoodBuilder};
 pub use crate::parcel::{Parcel, ParcelID};
 pub use crate::pathfind::{Path, PathRequest, PathStep, Pathfinder, Trace};
-pub use crate::road::{Road, RoadID};
+pub use crate::road::{DirectedRoadID, Road, RoadID};
 pub use crate::stop_signs::ControlStopSign;
 pub use crate::traffic_signals::{ControlTrafficSignal, Cycle};
 pub use crate::traversable::{Position, Traversable};

map_model/src/road.rs

@@ -15,6 +15,43 @@ impl fmt::Display for RoadID {
     }
 }
 
+impl RoadID {
+    pub fn forwards(self) -> DirectedRoadID {
+        DirectedRoadID {
+            id: self,
+            forwards: true,
+        }
+    }
+
+    pub fn backwards(self) -> DirectedRoadID {
+        DirectedRoadID {
+            id: self,
+            forwards: false,
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
+pub struct DirectedRoadID {
+    pub id: RoadID,
+    pub forwards: bool,
+}
+
+impl fmt::Display for DirectedRoadID {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(
+            f,
+            "DirectedRoadID({}, {})",
+            self.id.0,
+            if self.forwards {
+                "forwards"
+            } else {
+                "backwards"
+            }
+        )
+    }
+}
+
 // These're bidirectional (possibly)
 #[derive(Serialize, Deserialize, Debug)]
 pub struct Road {