inire/examples/README.md

Inire Routing Examples

This directory contains examples demonstrating the features and architectural capabilities of the inire router.

Architectural Visualization

In all plots generated by inire, we distinguish between the search-time geometry and the final "actual" geometry:

• Dashed Lines & Translucent Fill: The Collision Proxy used during the A* search (e.g., clipped_bbox or bbox). This represents the conservative envelope the router used to guarantee clearance.
• Solid Lines: The Actual Geometry (high-fidelity arcs). This is the exact shape that will be used for PDK generation and fabrication.

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Example Index

Example	Script	Output PNG	Summary
01	01_simple_route.py	01_simple_route.png	Single-net baseline route with one bend radius.
02	02_congestion_resolution.py	02_congestion_resolution.png	Small multi-net negotiated-congestion example.
03	03_locked_paths.py	03_locked_paths.png	Incremental routing with previously routed geometry treated as locked obstacles.
04	04_sbends_and_radii.py	04_sbends_and_radii.png	S-bend and bend-radius behavior on compact routes.
05	05_orientation_stress.py	05_orientation_stress.png	Orientation-heavy routing with flips, loops, and U-turn-like cases.
06	06_bend_collision_models.py	06_bend_collision_models.png	Comparison of bend collision/proxy geometry models.
07	07_large_scale_routing.py	07_large_scale_routing.png	Large fan-out through a bottleneck with negotiated congestion and expansion overlay.
08	08_custom_bend_geometry.py	08_custom_bend_geometry.png	Custom physical bend geometry and separate custom proxy geometry.
09	09_unroutable_best_effort.py	09_unroutable_best_effort.png	Best-effort partial routing for a blocked or unroutable net.

01. Simple Route

A minimal single-net example that routes one connection across an empty board and saves the result to 01_simple_route.png.

02. Congestion Resolution

Demonstrates negotiated congestion on a small multi-net problem where overlapping routes must be separated over successive iterations.

03. Locked Paths

Shows how to treat previously routed geometry as fixed static obstacles in a later run.

04. S-Bends And Radii

Highlights compact routing behavior with S-bends and the configured bend radii.

05. Orientation Stress Test

Demonstrates the router's ability to handle complex orientation requirements, including U-turns, 90-degree flips, and loops.

06. Bend Geometry Models

inire supports multiple collision models for bends, allowing a trade-off between search speed and geometric accuracy:

• Arc: High-fidelity geometry (Highest accuracy).
• BBox: Simple axis-aligned bounding box (Fastest search).
• Custom Manhattan Geometry: A custom 90-degree bend polygon with the same width as the normal waveguide.

Example 06 uses the Manhattan polygon as both the true routed bend geometry and the collision proxy.

07. Fan-Out (Negotiated Congestion)

Demonstrates the Negotiated Congestion algorithm handling multiple intersecting nets. The router iteratively increases penalties for overlaps until a collision-free solution is found. This example shows a bundle of nets fanning out through a narrow bottleneck.

08. Custom Bend Geometry

Compares the standard arc against a run that uses a custom physical bend plus a separate custom proxy polygon, with each net routed in its own session.

09. Unroutable Nets & Best-Effort Display

When a net is physically blocked or exceeds the node limit, the router returns the "best-effort" partial path—the path that reached the point closest to the target according to the heuristic. This is critical for debugging design constraints.

Notes

• Example 07 overlays expanded search nodes on the saved routing figure.
• The current implementation can use a cheaper bend proxy on the first negotiated-congestion pass before later passes fall back to the configured bend model. This is controlled by RoutingOptions.congestion.use_tiered_strategy together with the bend collision settings described in DOCS.md.