CircularString

View Markdown versionEdit this page on GitHub

Next version — This documentation describes a major version that is not yet the current stable release of spatial-types.

View the library roadmap

What is a CircularString?

A CircularString is a curve made of circular arcs joined end to end. An arc is described by its start point, a point on the arc and its end point; adjacent arcs share an endpoint.

This describes the intended curve geometry. Spatial Types stores the defining points without checking arc cardinality or geometric validity. Incomplete point sequences remain representable; use explicit geometric validation when needed.

CircularString — Supported representations

Availability in the current version of Spatial Types:

Coordinate layout	Geometry Mutable	Geometry Immutable	Geography Mutable	Geography Immutable
XY	✅	✅	✅	✅
XYZ	✅	✅	✅	✅
XYM	✅	✅	✅	✅
XYZM	✅	✅	✅	✅

Creating the illustrated objects

The examples recreate the labelled objects above using Geometry in XY. Composer’s autoloader must already be loaded. Variable names match the point letters in the illustration.

Immutable objects

<?php

use LongitudeOne\SpatialTypes\Types\Dimension2\Geometry\PointImmutable;
use LongitudeOne\SpatialTypes\Types\Dimension2\Geometry\CircularStringImmutable;

// Immutable objects must be fully initialized through their constructors.

$a = new PointImmutable(0, 0);
$b = new PointImmutable(1, 1);
$c = new PointImmutable(2, 0);
$d = new PointImmutable(-1, 0);
$e = new PointImmutable(0, 1);
$f = new PointImmutable(1, 0);
$g = new PointImmutable(1.5, -0.5);
$h = new PointImmutable(2, 0);

$arc = new CircularStringImmutable([$a, $b, $c]);
$joinedArcs = new CircularStringImmutable([$d, $e, $f, $g, $h]);

Mutable objects

<?php

use LongitudeOne\SpatialTypes\Types\Dimension2\Point;
use LongitudeOne\SpatialTypes\Types\Dimension2\CircularString;

$a = new Point(0, 0);
$b = new Point(1, 1);
$c = new Point(2, 0);
$d = new Point(-1, 0);
$e = new Point(0, 1);
$f = new Point(1, 0);
$g = new Point(1.5, -0.5);
$h = new Point(2, 0);

// Using the constructor.
$arc = new CircularString([$a, $b, $c]);

// Starting with an origin and appending arcs with methods.
$joinedArcs = new CircularString([])
    ->setOrigin($d)
    ->appendArc($e, $f)
    ->appendArc($g, $h);