foundation-planar-geometry

Planar rings in drawing units: parse and emit M/L/Z path text with the source's decimal scale kept, shoelace area with the closing edge and holes, bounding box, centroid, edge lengths, and the isometric projection a plan is drawn with. Policy-free and database-free.

Tier	foundation
Role	value_object
Path	`crates/foundation/planar-geometry`
Edition	2021
Targets	foundation_planar_geometry
Public items	28 across 1 module
Tests	13

What it is for

Planar rings in drawing units.

A drawing arrives as path text: M6.00,472.67L6.02,6.00 ... Z, repeated once per ring. This crate turns that text into rings of decimal points and back, keeping the decimal scale the source wrote (6.00 stays 6.00, 266.6 stays 266.6), so a ring that was not edited emits the text it was read from. Everything computed from a ring -- area, bounding box, centroid, edge lengths, an isometric projection -- is a pure function over those points.

No policy lives here: what a ring means (a lot, a road, a building) and what is acceptable for it belong to the crate that knows the domain.

Capabilities

`crate root`

Planar rings in drawing units.

Item
`fn parse_path(d : & str) -> Result <Vec <Ring>, PathError>`
`fn iso_project(u : f64, v : f64, z : f64) ->(f64, f64)`

`BBox`

Planar rings in drawing units.

Item
`pub struct BBox`
`BBox :: fn width(& self) -> f64`
`BBox :: fn height(& self) -> f64`
`fn bbox(rings : & Ring) -> Option <BBox>`

`PathError`

Planar rings in drawing units.

Item
`pub enum PathError`

`Point`

Planar rings in drawing units.

Item
`pub struct Point`
`Point :: fn new(x : Decimal, y : Decimal) -> Self`

`Ring`

Planar rings in drawing units.

Item
`pub struct Ring`
`fn emit_path(rings : & Ring, closed_repeat : bool) -> String`
`fn signed_area(ring : & Ring) -> f64`
`fn area(rings : & Ring) -> f64`
`fn centroid(ring : & Ring) ->(f64, f64)`
`fn edge_lengths(ring : & Ring) -> Vec <f64>`
`fn perimeter(ring : & Ring) -> f64`
`fn rounding_bound(ring : & Ring) -> f64`

`Region`

A region of the plane made of polygons, and the set arithmetic between regions.

Item
`pub struct Region`
`Region :: fn empty() -> Self`
`Region :: fn from_ring(ring : & (f64, f64)) -> Self`
`Region :: fn from_rings(rings : & Vec <(f64, f64)>) -> Self`
`Region :: fn union(& self, other : & Region) -> Region`
`Region :: fn difference(& self, other : & Region) -> Region`
`Region :: fn intersection(& self, other : & Region) -> Region`
`Region :: fn is_empty(& self) -> bool`
`Region :: fn area(& self) -> f64`
`Region :: fn polygon_count(& self) -> usize`
`Region :: fn rings(& self) -> Vec <Vec <(f64, f64)>>`

How to use it

No examples/ target and no doctest in this crate's rustdoc. The tests listed under Verification are the closest executable usage.

Module structure

foundation_planar_geometry

region

Public surface

`crate root`

Item	What it is
`pub struct Point`	One vertex, in the drawing's units, with the decimal scale the source wrote.
`Point :: fn new(x : Decimal, y : Decimal) -> Self`	—
`pub struct Ring`	A closed ring of vertices
`pub struct BBox`	The axis-aligned box around a set of rings.
`BBox :: fn width(& self) -> f64`	—
`BBox :: fn height(& self) -> f64`	—
`pub enum PathError`	—
`fn parse_path(d : & str) -> Result <Vec <Ring>, PathError>`	Parse path text made of `M x,y`, `L x,y` and `Z` into rings
`fn emit_path(rings : & Ring, closed_repeat : bool) -> String`	Emit rings as `M x,y L x,y ..
`fn signed_area(ring : & Ring) -> f64`	Signed shoelace area of one ring, including the closing edge
`fn area(rings : & Ring) -> f64`	Area of a figure made of rings: rings wound like the largest ring add, rings wound the other way are holes and subtract, and a ring of no area adds nothing
`fn bbox(rings : & Ring) -> Option <BBox>`	Bounding box over every vertex of every ring
`fn centroid(ring : & Ring) ->(f64, f64)`	Area-weighted centroid of one ring
`fn edge_lengths(ring : & Ring) -> Vec <f64>`	Length of each edge, in vertex order, closing edge last.
`fn perimeter(ring : & Ring) -> f64`	Perimeter of one ring, closing edge included.
`fn rounding_bound(ring : & Ring) -> f64`	The most the area of a ring can differ from the area of the exact figure it was rounded from: half a unit of the coarsest decimal scale among its vertices, times the perimeter
`fn iso_project(u : f64, v : f64, z : f64) ->(f64, f64)`	The 30-degree isometric projection: `(u, v, z)` in plan becomes `((u - v) cos 30°, (u + v) / 2 - z)`.

`region`

Item	What it is
`pub struct Region`	A set of polygons, possibly with holes, in drawing units.
`Region :: fn empty() -> Self`	The empty region.
`Region :: fn from_ring(ring : & (f64, f64)) -> Self`	One simple polygon from a closed ring (the closing edge implied).
`Region :: fn from_rings(rings : & Vec <(f64, f64)>) -> Self`	The union of every ring: overlapping rings merge, disjoint rings stay apart.
`Region :: fn union(& self, other : & Region) -> Region`	—
`Region :: fn difference(& self, other : & Region) -> Region`	What is in `self` and not in `other`.
`Region :: fn intersection(& self, other : & Region) -> Region`	—
`Region :: fn is_empty(& self) -> bool`	—
`Region :: fn area(& self) -> f64`	Unsigned area, holes subtracted.
`Region :: fn polygon_count(& self) -> usize`	—
`Region :: fn rings(& self) -> Vec <Vec <(f64, f64)>>`	Every ring as points: each polygon's exterior followed by its holes.

Re-exports. Exported here, defined elsewhere.

Export	Defined in
`Region`	`region::Region`

Boundary

Depends on no other workspace tier.

Shares tier foundation with 28 other crates: foundation-audit-log, foundation-basemodels, foundation-bounded-io, foundation-conversation-closure, foundation-crypto-sign, foundation-decisioning, foundation-encounter-vocabulary, foundation-fs-metadata, … (28 total).

_What this crate deliberately does NOT own is a judgment. No committed registry records one for it, so none is stated here._

Where it sits

Tier (ontology)	`foundation`
Architectural role (taxonomy)	`value_object`
Location	`crates/foundation/planar-geometry`
Vocabulary in force (lexicon)	`current`

Dependencies

Runtime, from outside the workspace.

Crate	Requirement	Features	Optional	Only on
`geo`	`^0.33`	—	no	always
`rust_decimal`	`^1`	`serde`	no	always
`thiserror`	`^2`	—	no	always

Development, from outside the workspace.

Crate	Requirement	Features	Optional	Only on
`rust_decimal_macros`	`^1`	—	no	always

Build. None.

Depended on by. 1 workspace crate.

Signal flow — what reaches this crate, and what it reaches.

flowchart LR
  n_domain_subdivision_plan["domain-subdivision-plan"] -->|uses| SELF
  SELF["foundation-planar-geometry"]
  classDef self fill:#1f883d,stroke:#1f883d,color:#fff;
  class SELF self;

Feature flags

No Cargo features are defined: every capability is unconditional, so no consumer can receive a half-wired crate.

Targets

Kind	Name	Source
lib	`foundation_planar_geometry`	`src/lib.rs`

Error model

Error type	Named by
`PathError`	`parse_path`

Operational characteristics

Property	Evidence
async public surface	none detected
async runtime	none detected
database access	none detected
network I/O	none detected
unsafe code	none detected
environment variables	none detected

No unsafe block, unsafe fn, unsafe impl or unsafe trait was found by the parser anywhere in this crate's source.

Configuration

No environment variable is read with a literal name anywhere in this crate. A variable whose key is computed at run time cannot be listed here, and is not claimed to be absent.

1 workspace crate depends on this one: domain-subdivision-plan.

Verification

Kind	Count
Unit tests	13
Integration tests	0
Examples	0
Doctests	0

Evidence by module. How often each public module is named by something executable.

Module	Tests	Examples	Consumers
`crate root`	14	0	10
`region`	1	0	1

What the tests establish, by name:

a_lot_of_ten_by_fifteen_has_those_edges_and_that_area — src/lib.rs
a_multi_ring_path_yields_one_ring_per_subpath — src/lib.rs
a_path_parses_to_rings_and_keeps_the_scale_it_was_written_with — src/lib.rs
a_path_without_a_move_or_with_a_curve_is_refused — src/lib.rs
an_unedited_ring_emits_the_text_it_was_read_from — src/lib.rs
bbox_and_centroid_are_computed_over_every_ring — src/lib.rs
shoelace_closes_the_ring_and_subtracts_holes — src/lib.rs
the_isometric_projection_is_the_one_the_plan_draws_with — src/lib.rs
the_predio_ring_measures_what_the_plan_declares_within_its_rounding_bound — src/lib.rs
the_rounding_bound_follows_the_coarsest_scale — src/lib.rs
a_hole_is_a_ring_and_counts_against_the_area — src/region.rs
layers_taken_in_order_tile_the_site_without_overlap — src/region.rs
union_merges_overlaps_and_difference_removes_them — src/region.rs

Documentation coverage

Measure	Documented	Total
Public items with rustdoc	20	28
Public modules with a `//!` block	1	1

pie showData
    title Public items with rustdoc
    "Documented" : 20
    "No rustdoc detected" : 8

Metrics

Metric	Value
Rust source files	2
Source lines	563
Code lines	456
Public API items	28
Public modules	1
Tests	13
Examples	0
Cargo features	0
Direct runtime dependencies	3
Workspace reverse dependencies	1

pie showData
    title Public API by kind
    "enum" : 1
    "function" : 10
    "method" : 13
    "struct" : 4

pie showData
    title Rust source composition
    "Code" : 456
    "Blank or comment" : 107

Generation

Rendered by tools-corpus corpus readme from repository evidence alone, renderer schema 2, lexicon current. No model, network service or database was consulted. Regenerate with tools-corpus corpus readme --write; verify with --check.

What it is for

Capabilities

crate root

BBox

PathError

Point

Ring

Region

How to use it

Module structure

Public surface

Boundary

Where it sits

Dependencies

Feature flags

Targets

Error model

Operational characteristics

Configuration

Related capabilities

Verification

Documentation coverage

Metrics

Generation

`crate root`

`BBox`

`PathError`

`Point`

`Ring`

`Region`