Make the conversion from geo::Polygon to geom::Polygon fallible

apps/game/src/edit/roads.rs

@@ -1013,11 +1013,19 @@ fn fade_irrelevant(app: &App, r: RoadID) -> GeomBatch {
     }
 
     // The convex hull illuminates a bit more of the surrounding area, looks better
-    let fade_area = Polygon::with_holes(
-        map.get_boundary_polygon().clone().into_ring(),
-        vec![Polygon::convex_hull(holes).into_ring()],
-    );
-    GeomBatch::from(vec![(app.cs.fade_map_dark, fade_area)])
+    match Polygon::convex_hull(holes) {
+        Ok(hole) => {
+            let fade_area = Polygon::with_holes(
+                map.get_boundary_polygon().clone().into_ring(),
+                vec![hole.into_ring()],
+            );
+            GeomBatch::from(vec![(app.cs.fade_map_dark, fade_area)])
+        }
+        Err(_) => {
+            // Just give up and don't fade anything
+            GeomBatch::new()
+        }
+    }
 }
 
 fn draw_drop_position(app: &App, r: RoadID, from: usize, to: usize) -> GeomBatch {

apps/game/src/edit/traffic_signals/mod.rs

@@ -944,11 +944,13 @@ fn squish_polygons_together(mut polygons: Vec<Polygon>) -> Vec<(f64, f64)> {
 
         // Do we hit anything if we move this way?
         let translated = polygons[idx].translate(pt.x(), pt.y());
-        if polygons
-            .iter()
-            .enumerate()
-            .any(|(i, p)| i != idx && !translated.intersection(p).is_empty())
-        {
+        if polygons.iter().enumerate().any(|(i, p)| {
+            i != idx
+                && !translated
+                    .intersection(p)
+                    .map(|list| list.is_empty())
+                    .unwrap_or(true)
+        }) {
             // Stop moving this polygon
         } else {
             translations[idx].0 += pt.x();
@@ -976,9 +978,17 @@ pub fn fade_irrelevant(app: &App, members: &BTreeSet<IntersectionID>) -> GeomBat
         }
     }
     // The convex hull illuminates a bit more of the surrounding area, looks better
-    let fade_area = Polygon::with_holes(
-        app.primary.map.get_boundary_polygon().clone().into_ring(),
-        vec![Polygon::convex_hull(holes).into_ring()],
-    );
-    GeomBatch::from(vec![(app.cs.fade_map_dark, fade_area)])
+    match Polygon::convex_hull(holes) {
+        Ok(hole) => {
+            let fade_area = Polygon::with_holes(
+                app.primary.map.get_boundary_polygon().clone().into_ring(),
+                vec![hole.into_ring()],
+            );
+            GeomBatch::from(vec![(app.cs.fade_map_dark, fade_area)])
+        }
+        Err(_) => {
+            // Just give up and don't fade anything
+            GeomBatch::new()
+        }
+    }
 }

apps/game/src/layer/traffic.rs

@@ -509,12 +509,14 @@ fn cluster_jams(map: &Map, problems: Vec<(IntersectionID, Time)>) -> Vec<(Polygo
         }
     }
 
+    // TODO This silently hides jams where we can't calculate the convex hull. The caller just
+    // needs a Tessellation, so should we have a less strict version of convex_hull?
     jams.into_iter()
-        .map(|jam| {
-            (
-                map.get_i(jam.epicenter).polygon.clone(),
-                Polygon::convex_hull(jam.all_polygons(map)),
-            )
+        .filter_map(|jam| {
+            let epicenter = map.get_i(jam.epicenter).polygon.clone();
+            Polygon::convex_hull(jam.all_polygons(map))
+                .ok()
+                .map(move |entire_shape| (epicenter, entire_shape))
         })
         .collect()
 }

apps/game/src/sandbox/dashboards/commuter.rs

@@ -1,5 +1,6 @@
 use std::collections::{BTreeSet, HashMap, HashSet};
 
+use anyhow::Result;
 use maplit::hashset;
 
 use abstutil::{prettyprint_usize, Counter, MultiMap, Timer};
@@ -8,7 +9,7 @@ use map_gui::tools::checkbox_per_mode;
 use map_model::{osm, BuildingID, BuildingType, IntersectionID, LaneID, Map, RoadID, TurnType};
 use sim::TripInfo;
 use synthpop::{TripEndpoint, TripMode};
-use widgetry::tools::ColorLegend;
+use widgetry::tools::{ColorLegend, PopupMsg};
 use widgetry::{
     Color, Drawable, EventCtx, GeomBatch, GfxCtx, HorizontalAlignment, Key, Line, Outcome, Panel,
     RewriteColor, Slider, State, Text, TextExt, Toggle, VerticalAlignment, Widget,
@@ -73,10 +74,23 @@ type BlockID = usize;
 
 impl CommuterPatterns {
     pub fn new_state(ctx: &mut EventCtx, app: &mut App) -> Box<dyn State<App>> {
-        let (bldg_to_block, border_to_block, blocks) = ctx
-            .loading_screen("group buildings into blocks", |_, timer| {
-                group_bldgs(app, timer)
-            });
+        let maybe_groups = ctx.loading_screen("group buildings into blocks", |_, timer| {
+            group_bldgs(app, timer)
+        });
+        let (bldg_to_block, border_to_block, blocks) = match maybe_groups {
+            Ok(result) => result,
+            Err(_) => {
+                // TODO If concave hull fails anywhere, give up on this tool entirely. This is
+                // pretty harsh. Revisit this tool anyway and consider 2 bigger changes -- using
+                // the LTN-style blockfinding and using World. Find a way to create simpler
+                // fallback geometry that's still selectable.
+                return PopupMsg::new_state(
+                    ctx,
+                    "Error",
+                    vec!["Problem rendering the grouped buildings; this tool won't work"],
+                );
+            }
+        };
 
         let mut trips_from_block: Vec<Vec<TripInfo>> = std::iter::repeat_with(Vec::new)
             .take(blocks.len())
@@ -458,16 +472,16 @@ impl State<App> for CommuterPatterns {
 fn group_bldgs(
     app: &App,
     timer: &mut Timer,
-) -> (
+) -> Result<(
     HashMap<BuildingID, BlockID>,
     HashMap<IntersectionID, BlockID>,
     Vec<Block>,
-) {
+)> {
     let mut bldg_to_block = HashMap::new();
     let mut blocks = Vec::new();
 
     let map = &app.primary.map;
-    for block in timer.parallelize(
+    for maybe_block in timer.parallelize(
         "draw neighborhoods",
         partition_sidewalk_loops(app)
             .into_iter()
@@ -493,14 +507,15 @@ fn group_bldgs(
                     hull_points.append(&mut lane_line.points().clone());
                 }
             }
-            Block {
+            Polygon::concave_hull(hull_points, 10).map(|shape| Block {
                 id: block_id,
                 bldgs: group.bldgs,
                 borders: HashSet::new(),
-                shape: Polygon::concave_hull(hull_points, 10),
-            }
+                shape,
+            })
         },
     ) {
+        let block = maybe_block?;
         for b in &block.bldgs {
             bldg_to_block.insert(*b, block.id);
         }
@@ -535,7 +550,7 @@ fn group_bldgs(
         });
     }
 
-    (bldg_to_block, border_to_block, blocks)
+    Ok((bldg_to_block, border_to_block, blocks))
 }
 
 enum BorderType {

apps/ltn/src/draw_cells.rs

@@ -73,10 +73,12 @@ impl RenderCells {
                 let color = cell_color.alpha(1.0).shade(0.2);
                 // If possible, try to erase where the cell boundary touches the perimeter road.
                 if let Some(ref neighbourhood_boundary) = neighbourhood_boundary {
-                    batch.extend(color, boundary.difference(neighbourhood_boundary));
-                } else {
-                    batch.push(color, boundary);
+                    if let Ok(list) = boundary.difference(neighbourhood_boundary) {
+                        batch.extend(color, list);
+                    }
+                    continue;
                 }
+                batch.push(color, boundary);
             }
         }
         batch
@@ -245,7 +247,12 @@ impl RenderCellsBuilder {
             // can just clip the result.
             let mut clipped = Vec::new();
             for p in cell_polygons {
-                clipped.extend(p.intersection(&result.boundary_polygon));
+                // If clipping fails, just use the original polygon.
+                if let Ok(list) = p.intersection(&result.boundary_polygon) {
+                    clipped.extend(list);
+                } else {
+                    clipped.push(p);
+                }
             }
 
             result.polygons_per_cell.push(clipped);

apps/parking_mapper/src/mapper.rs

@@ -645,7 +645,8 @@ fn find_overlapping_stuff(app: &App, timer: &mut Timer) -> Vec<Polygon> {
             if !b
                 .polygon
                 .intersection(&map.get_r(r).get_thick_polygon())
-                .is_empty()
+                .map(|list| list.is_empty())
+                .unwrap_or(true)
             {
                 polygons.push(b.polygon.clone());
             }
@@ -659,7 +660,8 @@ fn find_overlapping_stuff(app: &App, timer: &mut Timer) -> Vec<Polygon> {
             if !pl
                 .polygon
                 .intersection(&map.get_r(r).get_thick_polygon())
-                .is_empty()
+                .map(|list| list.is_empty())
+                .unwrap_or(true)
             {
                 polygons.push(pl.polygon.clone());
             }

convert_osm/src/lib.rs

@@ -181,14 +181,17 @@ fn clip_map(map: &mut RawMap, timer: &mut Timer) {
 
     let mut result_areas = Vec::new();
     for orig_area in map.areas.drain(..) {
-        for polygon in map
+        // If clipping fails, giving up on some areas is fine
+        if let Ok(list) = map
             .streets
             .boundary_polygon
             .intersection(&orig_area.polygon)
         {
-            let mut area = orig_area.clone();
-            area.polygon = polygon;
-            result_areas.push(area);
+            for polygon in list {
+                let mut area = orig_area.clone();
+                area.polygon = polygon;
+                result_areas.push(area);
+            }
         }
     }
     map.areas = result_areas;