Module model 

The domain-agnostic graph model — the same shape nornir’s src/viz/graph_render.rs::draw_graph accepts, so this engine is a future drop-in for that egui routine. Nodes are laid out in world space by the caller (each domain owns its own layout/columns); edges reference nodes by id. Decorations is the caller-supplied overlay — facett mustn’t know what a “release gate” is, so rings/badges/emphasis-edges are opaque here.

Colours are a tiny POD Color (premultiply-free sRGBA8) with a From conversion off egui’s Color32, so a caller already speaking egui (exactly nornir’s draw_graph) maps straight across with zero glue.

Structs

Camera

The camera transform: pan + zoom over the world. World point p projects to screen as center + pan + p * zoom (the same affine nornir’s draw_graph applies). Owned by the caller so navigation survives across frames.

Color

A straight sRGBA8 colour (NOT premultiplied). The render backends convert to their own colour type at the seam.

Decorations

The caller-supplied overlay layer (domain-agnostic). Per-node rings/badges keyed by node id, plus extra emphasis edges painted on top (e.g. a cycle’s suggested cut). Empty = no overlay.

GraphEdge

One edge: endpoints by node id, colour, a dashed flag, and an optional mid-edge label (a cut rationale).

GraphModel

The full graph to paint — nodes (laid out) + edges.

GraphNode

One laid-out node: stable id, label, chip fill + stroke (the kind colour, caller’s choice), and its world-space centre.

NodeDecoration

A per-node decoration layered over the base chip: an optional status ring colour (drawn outside the kind stroke), an optional badge (a short glyph/text at the chip’s top-right corner), and an optional scale — a multiplier on the node’s marker radius so a caller can size nodes by an importance metric (population, degree, …) without the engine learning what the metric means. The L0 lowering reads scale (default 1.0) when it sizes the node marker.

Pos

A 2D point in world space (caller-owned layout coordinates).

Constants

BOX_H

BOX_W

Default node chip size in world units (matches nornir’s arch board: BOX_W/BOX_H), before any pan/zoom transform.