At really low zoom levels, draw modal filters using the scale-invariant

circles. Otherwise they're just impossible to see. Since they're the
most important thing to show in the LTN tool, seems worth it.

This helps proceed on #851

ltn/src/browse.rs

@@ -11,13 +11,13 @@ use widgetry::{
 };
 
 use super::{Neighborhood, NeighborhoodID, Partitioning};
-use crate::{App, ModalFilters, Transition};
+use crate::{App, ModalFilters, Toggle3Zoomed, Transition};
 
 pub struct BrowseNeighborhoods {
     panel: Panel,
     world: World<NeighborhoodID>,
     labels: DrawRoadLabels,
-    draw_all_filters: ToggleZoomed,
+    draw_all_filters: Toggle3Zoomed,
     draw_boundary_roads: ToggleZoomed,
 }
 
@@ -173,10 +173,10 @@ impl State<App> for BrowseNeighborhoods {
         crate::draw_with_layering(g, app, |g| self.world.draw(g));
 
         self.panel.draw(g);
-        self.draw_all_filters.draw(g);
         if self.panel.is_checked("highlight boundary roads") {
             self.draw_boundary_roads.draw(g);
         }
+        self.draw_all_filters.draw(g);
         if g.canvas.is_unzoomed() {
             self.labels.draw(g, app);
         }
@@ -249,7 +249,7 @@ fn draw_boundary_roads(ctx: &EventCtx, app: &App) -> ToggleZoomed {
             let road = app.map.get_r(r);
             batch
                 .unzoomed
-                .push(Color::RED.alpha(0.8), road.get_thick_polygon());
+                .push(Color::RED.alpha(0.6), road.get_thick_polygon());
             batch
                 .zoomed
                 .push(Color::RED.alpha(0.5), road.get_thick_polygon());
@@ -261,7 +261,7 @@ fn draw_boundary_roads(ctx: &EventCtx, app: &App) -> ToggleZoomed {
                 seen_borders.insert(i);
                 batch
                     .unzoomed
-                    .push(Color::RED.alpha(0.8), app.map.get_i(i).polygon.clone());
+                    .push(Color::RED.alpha(0.6), app.map.get_i(i).polygon.clone());
                 batch
                     .zoomed
                     .push(Color::RED.alpha(0.5), app.map.get_i(i).polygon.clone());

ltn/src/filters.rs

@@ -4,8 +4,8 @@ use serde::{Deserialize, Serialize};
 
 use geom::{Circle, Distance, Line};
 use map_model::{IntersectionID, Map, RoadID, RoutingParams, TurnID};
-use widgetry::mapspace::ToggleZoomed;
-use widgetry::{Color, EventCtx, GeomBatch};
+use widgetry::mapspace::{DrawUnzoomedShapes, ToggleZoomed};
+use widgetry::{Color, EventCtx, GeomBatch, GfxCtx};
 
 use super::Neighborhood;
 use crate::App;
@@ -88,8 +88,10 @@ impl ModalFilters {
         ctx: &EventCtx,
         map: &Map,
         only_neighborhood: Option<&Neighborhood>,
-    ) -> ToggleZoomed {
+    ) -> Toggle3Zoomed {
         let mut batch = ToggleZoomed::builder();
+        let mut low_zoom = DrawUnzoomedShapes::builder();
+
         for (r, dist) in &self.roads {
             if only_neighborhood
                 .map(|n| !n.orig_perimeter.interior.contains(r))
@@ -102,6 +104,11 @@ impl ModalFilters {
             if let Ok((pt, angle)) = road.center_pts.dist_along(*dist) {
                 let road_width = road.get_width();
 
+                // TODO DrawUnzoomedShapes can do lines, but they don't stretch as the radius does,
+                // so it looks weird
+                low_zoom.add_circle(pt, Distance::meters(8.0), Color::RED);
+                low_zoom.add_circle(pt, Distance::meters(6.0), Color::WHITE);
+
                 batch
                     .unzoomed
                     .push(Color::RED, Circle::new(pt, road_width).to_polygon());
@@ -134,6 +141,13 @@ impl ModalFilters {
             }
 
             let line = filter.geometry(map);
+
+            // It's really hard to see a tiny squished line thickened, so use the same circle
+            // symbology at really low zooms
+            let pt = line.middle().unwrap();
+            low_zoom.add_circle(pt, Distance::meters(8.0), Color::RED);
+            low_zoom.add_circle(pt, Distance::meters(6.0), Color::WHITE);
+
             batch
                 .unzoomed
                 .push(Color::RED, line.make_polygons(Distance::meters(3.0)));
@@ -144,7 +158,7 @@ impl ModalFilters {
                 line.percent_slice(0.3, 0.7).unwrap_or(line),
             );
         }
-        batch.build(ctx)
+        Toggle3Zoomed::new(batch.build(ctx), low_zoom.build())
     }
 }
 
@@ -250,3 +264,27 @@ fn draw_zoomed_planters(ctx: &EventCtx, batch: &mut GeomBatch, line: Line) {
             .rotate(line.angle()),
     );
 }
+
+/// Depending on the canvas zoom level, draws one of 3 things.
+pub struct Toggle3Zoomed {
+    draw: ToggleZoomed,
+    unzoomed: DrawUnzoomedShapes,
+}
+
+impl Toggle3Zoomed {
+    fn new(draw: ToggleZoomed, unzoomed: DrawUnzoomedShapes) -> Self {
+        Self { draw, unzoomed }
+    }
+
+    pub fn empty(ctx: &EventCtx) -> Self {
+        Self::new(ToggleZoomed::empty(ctx), DrawUnzoomedShapes::empty())
+    }
+
+    pub fn draw(&self, g: &mut GfxCtx) {
+        if g.canvas.cam_zoom < 1.0 {
+            self.unzoomed.draw(g);
+        } else {
+            self.draw.draw(g);
+        }
+    }
+}

ltn/src/impact/ui.rs

@@ -3,21 +3,20 @@ use std::collections::BTreeSet;
 use map_gui::load::FileLoader;
 use map_gui::tools::{checkbox_per_mode, PopupMsg};
 use synthpop::{Scenario, TripMode};
-use widgetry::mapspace::ToggleZoomed;
 use widgetry::{
     Drawable, EventCtx, GeomBatch, GfxCtx, HorizontalAlignment, Line, Panel, SimpleState, Slider,
     State, Text, TextExt, Toggle, VerticalAlignment, Widget,
 };
 
 use super::{end_of_day, Filters, Impact};
-use crate::{App, BrowseNeighborhoods, Transition};
+use crate::{App, BrowseNeighborhoods, Toggle3Zoomed, Transition};
 
 // TODO Share structure or pieces with Ungap's predict mode
 // ... can't we just produce data of a certain shape, and have a UI pretty tuned for that?
 
 pub struct ShowResults {
     draw_all_neighborhoods: Drawable,
-    draw_all_filters: ToggleZoomed,
+    draw_all_filters: Toggle3Zoomed,
 }
 
 impl ShowResults {

ltn/src/lib.rs

@@ -5,7 +5,7 @@ use structopt::StructOpt;
 use widgetry::{GfxCtx, Settings};
 
 pub use browse::BrowseNeighborhoods;
-pub use filters::{DiagonalFilter, ModalFilters};
+pub use filters::{DiagonalFilter, ModalFilters, Toggle3Zoomed};
 pub use neighborhood::{Cell, DistanceInterval, Neighborhood};
 pub use partition::{NeighborhoodID, Partitioning};
 
@@ -63,7 +63,7 @@ fn run(mut settings: Settings) {
 
             impact: impact::Impact::empty(ctx),
 
-            highlight_boundary_roads: true,
+            highlight_boundary_roads: false,
             draw_neighborhood_style: browse::Style::SimpleColoring,
             draw_cells_as_areas: true,
             draw_borders_as_arrows: true,

ltn/src/neighborhood.rs

@@ -5,10 +5,9 @@ use maplit::btreeset;
 use geom::{Distance, Polygon};
 use map_gui::tools::DrawRoadLabels;
 use map_model::{IntersectionID, Map, PathConstraints, Perimeter, RoadID};
-use widgetry::mapspace::ToggleZoomed;
 use widgetry::{Drawable, EventCtx, GeomBatch};
 
-use crate::{App, ModalFilters, NeighborhoodID};
+use crate::{App, ModalFilters, NeighborhoodID, Toggle3Zoomed};
 
 pub struct Neighborhood {
     pub id: NeighborhoodID,
@@ -24,7 +23,7 @@ pub struct Neighborhood {
     pub cells: Vec<Cell>,
 
     pub fade_irrelevant: Drawable,
-    pub draw_filters: ToggleZoomed,
+    pub draw_filters: Toggle3Zoomed,
     pub labels: DrawRoadLabels,
 }
 
@@ -74,7 +73,7 @@ impl Neighborhood {
             cells: Vec::new(),
 
             fade_irrelevant: Drawable::empty(ctx),
-            draw_filters: ToggleZoomed::empty(ctx),
+            draw_filters: Toggle3Zoomed::empty(ctx),
             // Temporary value
             labels: DrawRoadLabels::only_major_roads(),
         };