Geometry

Geometry is the only layer that knows the picture is isometric. It projects LevelPlans into a Scene in paint order, so render writes it in sequence.

Components

Projection

• screen = ((x − y)·√3/2, (x + y)/2 − z), √3/2 stored as a literal, so no trigonometry runs.
• Each level gets its own frame, mapping it into its parent, and its own view, the rectangle the runtime zooms to.

Primitives

• Footprints extrude into a block (leaves, default 22.5 tall), slab (containers, 10.5), cylinder (25.5) or disc (10.5).
• A closed container is drawn as a leaf over a faint 4.5-unit sheet hinting at its contents.

Depth sorts each level’s solids back to front: a footprint paints first when a sight line x − y = k meets it before the other.

Connections are quadratic Béziers from port to port, the apex 20 + 0.2·span plan units above the higher port, so long arcs clear what they cross.

Plates put each connection label, stub tag and badge at the candidate spot overlapping the fewest labels and earlier plates.

Stubs and badges route nothing.

• A stub tag lies flat on its container’s slab by its slot.
• A badge is its target shrunk to 19.2 screen units on its source’s top face.
• Adding or removing either moves no arc (tested in crates/svugy/src/lib.rs).

Heading and legend sit in document space, outside every level’s frame.

Code: crates/svugy/src/geometry/.