Color rails by traffic

[lukacslacko]

No description provided.

[Copilot]

Pull Request Overview

This PR introduces traffic-based coloring for rails by tracking and visualizing segment usage.

• Added a global max_rail_usage counter to State and initialized it in the UI setup.
• Updated the train update logic to increment per-rail counters, update the global maximum, and compute rail colors based on usage.
• Simplified the UI’s path rendering by removing dynamic start/end coloring and refactoring entity insertion.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/ui.rs	Initialized max_rail_usage, refactored rail entity insertion, and set default path color to white
src/train.rs	Incremented per-rail usage, updated global max via fetch_max, and applied heatmap coloring
src/state.rs	Added max_rail_usage: AtomicUsize field to the application State

Comments suppressed due to low confidence (1)

src/train.rs:133

• [nitpick] Using the return value of fetch_max together with count.max(...) can be confusing. Consider calling state.max_rail_usage.fetch_max(count, Ordering::Relaxed) first, then loading the updated maximum with state.max_rail_usage.load(Ordering::Relaxed) to make the intent clearer.

let max_rail_usage = count.max(state.max_rail_usage.fetch_max(count, Ordering::Relaxed));

[Copilot]

Using Entry::Vacant only handles the case where the rail is absent; the occupied case isn’t handled, and entity is unbound outside the block. Consider using match state.rails.rails.entry(rail) to cover both Occupied and Vacant branches and bind entity accordingly.

[Copilot]

[nitpick] Using 0.into() to initialize an AtomicUsize can be unclear. Consider using AtomicUsize::new(0) for explicitness and readability.

Suggested change

	max_rail_usage: 0.into(),
	max_rail_usage: AtomicUsize::new(0),