feat: add batching & merging of lines in debug rendering

src/app.rs

@@ -89,7 +89,7 @@ impl App {
             let start = Instant::now();
 
             let dt = self.last_tick.elapsed().as_secs_f32();
-            self.last_tick = Instant::now();
+            self.last_tick = start;
 
             let exit = self.game.tick(dt);
 

src/constants.rs

@@ -8,8 +8,8 @@ use glam::UVec2;
 ///
 /// Calculated as 1/60th of a second (≈16.67ms).
 ///
-/// Written out explicitly to satisfy const-eval constraints.
-pub const LOOP_TIME: Duration = Duration::from_nanos((1_000_000_000.0 / 60.0) as u64);
+/// Uses integer arithmetic to avoid floating-point precision loss.
+pub const LOOP_TIME: Duration = Duration::from_nanos(1_000_000_000 / 60);
 
 /// The size of each cell, in pixels.
 pub const CELL_SIZE: u32 = 8;

src/game.rs

@@ -31,6 +31,7 @@ use bevy_ecs::schedule::common_conditions::resource_changed;
 use bevy_ecs::schedule::{Condition, IntoScheduleConfigs, Schedule, SystemSet};
 use bevy_ecs::system::ResMut;
 use bevy_ecs::world::World;
+use glam::UVec2;
 use sdl2::event::EventType;
 use sdl2::image::LoadTexture;
 use sdl2::render::{BlendMode, Canvas, ScaleMode, TextureCreator};
@@ -42,7 +43,7 @@ use crate::{
     asset::{get_asset_bytes, Asset},
     events::GameCommand,
     map::render::MapRenderer,
-    systems::debug::TtfAtlasResource,
+    systems::debug::{BatchedLinesResource, TtfAtlasResource},
     systems::input::{Bindings, CursorPosition},
     texture::sprite::{AtlasMapper, SpriteAtlas},
 };
@@ -126,7 +127,7 @@ impl Game {
             EventType::Display,
             EventType::Window,
             EventType::MouseWheel,
-            EventType::MouseMotion,
+            // EventType::MouseMotion,
             EventType::MouseButtonDown,
             EventType::MouseButtonUp,
             EventType::MouseButtonDown,
@@ -299,6 +300,10 @@ impl Game {
         EventRegistry::register_event::<GameEvent>(&mut world);
         EventRegistry::register_event::<AudioEvent>(&mut world);
 
+        let scale =
+            (UVec2::from(canvas.output_size().unwrap()).as_vec2() / UVec2::from(canvas.logical_size()).as_vec2()).min_element();
+
+        world.insert_resource(BatchedLinesResource::new(&map, scale));
         world.insert_resource(Self::create_ghost_animations(&atlas)?);
         world.insert_resource(map);
         world.insert_resource(GlobalState { exit: false });

src/systems/debug.rs

@@ -12,6 +12,9 @@ use sdl2::pixels::Color;
 use sdl2::rect::{Point, Rect};
 use sdl2::render::{Canvas, Texture};
 use sdl2::video::Window;
+use smallvec::SmallVec;
+use std::collections::{HashMap, HashSet};
+use tracing::warn;
 
 #[derive(Resource, Default, Debug, Copy, Clone)]
 pub struct DebugState {
@@ -28,6 +31,118 @@ pub struct DebugTextureResource(pub Texture);
 /// Resource to hold the TTF text atlas
 pub struct TtfAtlasResource(pub TtfAtlas);
 
+/// Resource to hold pre-computed batched line segments
+#[derive(Resource, Default, Debug, Clone)]
+pub struct BatchedLinesResource {
+    horizontal_lines: Vec<(i32, i32, i32)>, // (y, x_start, x_end)
+    vertical_lines: Vec<(i32, i32, i32)>,   // (x, y_start, y_end)
+}
+
+impl BatchedLinesResource {
+    /// Computes and caches batched line segments for the map graph
+    pub fn new(map: &Map, scale: f32) -> Self {
+        let mut horizontal_segments: HashMap<i32, Vec<(i32, i32)>> = HashMap::new();
+        let mut vertical_segments: HashMap<i32, Vec<(i32, i32)>> = HashMap::new();
+        let mut processed_edges: HashSet<(u16, u16)> = HashSet::new();
+
+        // Process all edges and group them by axis
+        for (start_node_id, edge) in map.graph.edges() {
+            // Acquire a stable key for the edge (from < to)
+            let edge_key = (start_node_id.min(edge.target), start_node_id.max(edge.target));
+
+            // Skip if we've already processed this edge in the reverse direction
+            if processed_edges.contains(&edge_key) {
+                continue;
+            }
+            processed_edges.insert(edge_key);
+
+            let start_pos = map.graph.get_node(start_node_id).unwrap().position;
+            let end_pos = map.graph.get_node(edge.target).unwrap().position;
+
+            let start = transform_position_with_offset(start_pos, scale);
+            let end = transform_position_with_offset(end_pos, scale);
+
+            // Determine if this is a horizontal or vertical line
+            if (start.y - end.y).abs() < 2 {
+                // Horizontal line (allowing for slight vertical variance)
+                let y = start.y;
+                let x_min = start.x.min(end.x);
+                let x_max = start.x.max(end.x);
+                horizontal_segments.entry(y).or_default().push((x_min, x_max));
+            } else if (start.x - end.x).abs() < 2 {
+                // Vertical line (allowing for slight horizontal variance)
+                let x = start.x;
+                let y_min = start.y.min(end.y);
+                let y_max = start.y.max(end.y);
+                vertical_segments.entry(x).or_default().push((y_min, y_max));
+            }
+        }
+
+        /// Merges overlapping or adjacent segments into continuous lines
+        fn merge_segments(segments: Vec<(i32, i32)>) -> Vec<(i32, i32)> {
+            if segments.is_empty() {
+                return Vec::new();
+            }
+
+            let mut merged = Vec::new();
+            let mut current_start = segments[0].0;
+            let mut current_end = segments[0].1;
+
+            for &(start, end) in segments.iter().skip(1) {
+                if start <= current_end + 1 {
+                    // Adjacent or overlapping
+                    current_end = current_end.max(end);
+                } else {
+                    merged.push((current_start, current_end));
+                    current_start = start;
+                    current_end = end;
+                }
+            }
+
+            merged.push((current_start, current_end));
+            merged
+        }
+
+        // Convert to flat vectors for fast iteration during rendering
+        let horizontal_lines = horizontal_segments
+            .into_iter()
+            .flat_map(|(y, mut segments)| {
+                segments.sort_unstable_by_key(|(start, _)| *start);
+                let merged = merge_segments(segments);
+                merged.into_iter().map(move |(x_start, x_end)| (y, x_start, x_end))
+            })
+            .collect::<Vec<_>>();
+
+        let vertical_lines = vertical_segments
+            .into_iter()
+            .flat_map(|(x, mut segments)| {
+                segments.sort_unstable_by_key(|(start, _)| *start);
+                let merged = merge_segments(segments);
+                merged.into_iter().map(move |(y_start, y_end)| (x, y_start, y_end))
+            })
+            .collect::<Vec<_>>();
+
+        Self {
+            horizontal_lines,
+            vertical_lines,
+        }
+    }
+
+    pub fn render(&self, canvas: &mut Canvas<Window>) {
+        // Render horizontal lines
+        for &(y, x_start, x_end) in &self.horizontal_lines {
+            let points = [Point::new(x_start, y), Point::new(x_end, y)];
+            let _ = canvas.draw_lines(&points[..]);
+        }
+
+        // Render vertical lines
+        for &(x, y_start, y_end) in &self.vertical_lines {
+            let points = [Point::new(x, y_start), Point::new(x, y_end)];
+            let _ = canvas.draw_lines(&points[..]);
+        }
+    }
+}
+
 /// Transforms a position from logical canvas coordinates to output canvas coordinates (with board offset)
 fn transform_position_with_offset(pos: Vec2, scale: f32) -> IVec2 {
     ((pos + BOARD_PIXEL_OFFSET.as_vec2()) * scale).as_ivec2()
@@ -91,6 +206,7 @@ pub fn debug_render_system(
     mut canvas: NonSendMut<&mut Canvas<Window>>,
     mut debug_texture: NonSendMut<DebugTextureResource>,
     mut ttf_atlas: NonSendMut<TtfAtlasResource>,
+    batched_lines: Res<BatchedLinesResource>,
     debug_state: Res<DebugState>,
     timings: Res<SystemTimings>,
     map: Res<Map>,
@@ -131,55 +247,70 @@ pub fn debug_render_system(
             };
 
             debug_canvas.set_draw_color(Color::GREEN);
-            for (collider, position) in colliders.iter() {
-                let pos = position.get_pixel_position(&map.graph).unwrap();
+            {
+                let rects = colliders
+                    .iter()
+                    .map(|(collider, position)| {
+                        let pos = position.get_pixel_position(&map.graph).unwrap();
 
-                // Transform position and size using common methods
-                let pos = (pos * scale).as_ivec2();
-                let size = (collider.size * scale) as u32;
+                        // Transform position and size using common methods
+                        let pos = (pos * scale).as_ivec2();
+                        let size = (collider.size * scale) as u32;
 
-                let rect = Rect::from_center(Point::from((pos.x, pos.y)), size, size);
-                debug_canvas.draw_rect(rect).unwrap();
+                        Rect::from_center(Point::from((pos.x, pos.y)), size, size)
+                    })
+                    .collect::<SmallVec<[Rect; 100]>>();
+                if rects.len() > rects.capacity() {
+                    warn!(
+                        capacity = rects.capacity(),
+                        count = rects.len(),
+                        "Collider rects capacity exceeded"
+                    );
+                }
+                debug_canvas.draw_rects(&rects).unwrap();
             }
 
             debug_canvas.set_draw_color(Color {
-                a: f32_to_u8(0.4),
+                a: f32_to_u8(0.6),
                 ..Color::RED
             });
             debug_canvas.set_blend_mode(sdl2::render::BlendMode::Blend);
-            for (start_node, end_node) in map.graph.edges() {
-                let start_node_model = map.graph.get_node(start_node).unwrap();
-                let end_node = map.graph.get_node(end_node.target).unwrap().position;
 
-                // Transform positions using common method
-                let start = transform_position_with_offset(start_node_model.position, scale);
-                let end = transform_position_with_offset(end_node, scale);
+            // Use cached batched line segments
+            batched_lines.render(debug_canvas);
 
-                debug_canvas
-                    .draw_line(Point::from((start.x, start.y)), Point::from((end.x, end.y)))
-                    .unwrap();
-            }
+            {
+                let rects: Vec<_> = map
+                    .graph
+                    .nodes()
+                    .enumerate()
+                    .filter_map(|(id, node)| {
+                        let pos = transform_position_with_offset(node.position, scale);
+                        let size = (2.0 * scale) as u32;
+                        let rect = Rect::new(pos.x - (size as i32 / 2), pos.y - (size as i32 / 2), size, size);
 
-            for (id, node) in map.graph.nodes().enumerate() {
-                let pos = node.position;
+                        // If the node is the one closest to the cursor, draw it immediately
+                        if closest_node == Some(id) {
+                            debug_canvas.set_draw_color(Color::YELLOW);
+                            debug_canvas.fill_rect(rect).unwrap();
+                            return None;
+                        }
 
-                // Set color based on whether the node is the closest to the cursor
-                debug_canvas.set_draw_color(Color {
-                    a: f32_to_u8(if Some(id) == closest_node { 0.75 } else { 0.6 }),
-                    ..(if Some(id) == closest_node {
-                        Color::YELLOW
-                    } else {
-                        Color::BLUE
+                        Some(rect)
                     })
-                });
+                    .collect();
 
-                // Transform position using common method
-                let pos = transform_position_with_offset(pos, scale);
-                let size = (2.0 * scale) as u32;
+                if rects.len() > rects.capacity() {
+                    warn!(
+                        capacity = rects.capacity(),
+                        count = rects.len(),
+                        "Node rects capacity exceeded"
+                    );
+                }
 
-                debug_canvas
-                    .fill_rect(Rect::new(pos.x - (size as i32 / 2), pos.y - (size as i32 / 2), size, size))
-                    .unwrap();
+                // Draw the non-closest nodes all at once in blue
+                debug_canvas.set_draw_color(Color::BLUE);
+                debug_canvas.fill_rects(&rects).unwrap();
             }
 
             // Render node ID if a node is highlighted

src/systems/input.rs

@@ -138,14 +138,12 @@ pub fn input_system(
 
     // Warn if the smallvec was heap allocated due to exceeding stack capacity
     #[cfg(debug_assertions)]
-    {
-        if frame_events.len() > frame_events.capacity() {
-            tracing::warn!(
-                "More than {} events in a frame, consider adjusting stack capacity: {:?}",
-                frame_events.capacity(),
-                frame_events
-            );
-        }
+    if frame_events.len() > frame_events.capacity() {
+        tracing::warn!(
+            "More than {} events in a frame, consider adjusting stack capacity: {:?}",
+            frame_events.capacity(),
+            frame_events
+        );
     }
 
     // Handle non-keyboard events inline and build a simplified keyboard event stream.

src/systems/profiling.rs

@@ -7,8 +7,8 @@ use parking_lot::{Mutex, RwLock};
 use smallvec::SmallVec;
 use std::fmt::Display;
 use std::time::Duration;
-use strum::EnumCount;
-use strum_macros::{EnumCount, IntoStaticStr};
+use strum::{EnumCount, IntoEnumIterator};
+use strum_macros::{EnumCount, EnumIter, IntoStaticStr};
 use thousands::Separable;
 
 /// The maximum number of systems that can be profiled. Must not be exceeded, or it will panic.
@@ -16,7 +16,7 @@ const MAX_SYSTEMS: usize = SystemId::COUNT;
 /// The number of durations to keep in the circular buffer.
 const TIMING_WINDOW_SIZE: usize = 30;
 
-#[derive(EnumCount, IntoStaticStr, Debug, PartialEq, Eq, Hash, Copy, Clone)]
+#[derive(EnumCount, EnumIter, IntoStaticStr, Debug, PartialEq, Eq, Hash, Copy, Clone)]
 pub enum SystemId {
     Input,
     PlayerControls,
@@ -96,7 +96,7 @@ impl SystemTimings {
             let sum: f64 = durations.iter().sum();
             let mean = sum / count;
 
-            let variance = durations.iter().map(|x| (x - mean).powi(2)).sum::<f64>() / count;
+            let variance = durations.iter().map(|x| (x - mean).powi(2)).sum::<f64>() / (count - 1.0).max(1.0);
             let std_dev = variance.sqrt();
 
             stats.insert(
@@ -128,7 +128,7 @@ impl SystemTimings {
                 diff_secs * diff_secs
             })
             .sum::<f64>()
-            / duration_sums.len() as f64;
+            / (duration_sums.len() - 1).max(1) as f64;
         let std_dev_secs = variance.sqrt();
 
         (mean, Duration::from_secs_f64(std_dev_secs))
@@ -250,17 +250,22 @@ pub fn format_timing_display(
         })
         .collect::<SmallVec<[Entry; 12]>>();
 
-    let (max_name_width, max_avg_int_width, max_avg_decimal_width, max_std_int_width, max_std_decimal_width) = entries
-        .iter()
-        .fold((0, 0, 3, 0, 3), |(name_w, avg_int_w, avg_dec_w, std_int_w, std_dec_w), e| {
-            (
-                name_w.max(e.name.len()),
-                avg_int_w.max(e.avg_int.width() as usize),
-                avg_dec_w.max(e.avg_decimal.width() as usize),
-                std_int_w.max(e.std_int.width() as usize),
-                std_dec_w.max(e.std_decimal.width() as usize),
-            )
-        });
+    let (max_avg_int_width, max_avg_decimal_width, max_std_int_width, max_std_decimal_width) =
+        entries
+            .iter()
+            .fold((0, 3, 0, 3), |(avg_int_w, avg_dec_w, std_int_w, std_dec_w), e| {
+                (
+                    avg_int_w.max(e.avg_int.width() as usize),
+                    avg_dec_w.max(e.avg_decimal.width() as usize),
+                    std_int_w.max(e.std_int.width() as usize),
+                    std_dec_w.max(e.std_decimal.width() as usize),
+                )
+            });
+
+    let max_name_width = SystemId::iter()
+        .map(|id| id.to_string().len())
+        .max()
+        .expect("SystemId::iter() returned an empty iterator");
 
     entries.iter().map(|e| {
             format!(

tests/profiling.rs

@@ -14,6 +14,7 @@ fn test_timing_statistics() {
     timings.add_timing(SystemId::Blinking, Duration::from_millis(3));
     timings.add_timing(SystemId::Blinking, Duration::from_millis(2));
     timings.add_timing(SystemId::Blinking, Duration::from_millis(1));
+
     fn close_enough(a: Duration, b: Duration) -> bool {
         if a > b {
             a - b < Duration::from_micros(500) // 0.1ms
@@ -36,25 +37,8 @@ fn test_timing_statistics() {
         total_avg
     );
     assert!(
-        close_enough(total_std, Duration::from_millis(12)),
+        close_enough(total_std, Duration::from_millis(17)),
         "total_std: {:?}",
         total_std
     );
 }
-
-// #[test]
-// fn test_window_size_limit() {
-//     let timings = SystemTimings::default();
-
-//     // Add more than 90 timings to test window size limit
-//     for i in 0..100 {
-//         timings.add_timing("test_system", Duration::from_millis(i));
-//     }
-
-//     let stats = timings.get_stats();
-//     let (avg, _) = stats.get("test_system").unwrap();
-
-//     // Should only keep the last 90 values, so average should be around 55ms
-//     // (average of 10-99)
-//     assert!((avg.as_millis() as f64 - 55.0).abs() < 5.0);
-// }