Module Hugin_gg_kit.Ring2

Linear rings.

A ring is a closed polygonal curve: points in order, each joined to the next by a straight segment and the last to the first. A ring may cross or touch itself. A ring of fewer than three points encloses nothing: its winding number is 0 around every point off it. Orientation, winding numbers and signed areas follow the conventions. Rings store their coordinates in two float arrays, without a block per point.

Types

#type t

The type for rings. Invariant: coordinates are finite.

Constructors

#val v : float array -> float array -> t

v xs ys is the ring through the points (xs.(i), ys.(i)) in order. The arrays are copied.

Raises Invalid_argument if xs and ys differ in length or a coordinate is not finite.

Accessors

Functions that take a point index raise Invalid_argument if it is not in [0;length r - 1].

#val length : t -> int

length r is the number of points of r.

#val x : t -> int -> float

x r i is the x coordinate of point i of r.

#val y : t -> int -> float

y r i is the y coordinate of point i of r.

Measures

#val area : t -> float

area r is the signed area of r, computed with rounding: positive if r is positively oriented and negative if negatively, unless the area is within rounding error of zero, and 0. if r has fewer than three points. It overflows to an infinity or NaN if r spans more than about 10¹⁵⁴.

#val bounds : t -> Hugin_gg.Box2.t option

bounds r is the smallest box containing the points of r, or None if r has no point.

Transforming and converting

#val reverse : t -> t

reverse r is r with its points in reverse order: point i of reverse r is point length r - 1 - i of r. Its orientation, signed area and winding numbers are those of r negated.

#val to_path : t -> Hugin_gg.Path.t

to_path r is the closed subpath through the points of r in order, Hugin_gg.Path.polygon of its coordinates. It is Hugin_gg.Path.empty if r has fewer than two points.

Comparing and formatting

#val equal : t -> t -> bool

equal r r' is true iff r and r' have equal points in the same order from the same first point. A ring and its rotation, which draw the same curve, are not equal.

#val pp : Stdlib.Format.formatter -> t -> unit

pp ppf r formats the points of r as SVG path data, M x y for the first point, L x y for each other and a final Z, with numbers printed with %g. A ring with no point formats as nothing.