Data.Geometry.Polygon

A Polygon data type and some basic functions to interact with them.

Documentation

data PolygonType

We distinguish between simple polygons (without holes) and Polygons with holes.

Constructors

Simple

Multi

data Polygon (t :: PolygonType) p r where

Constructors

SimplePolygon :: CSeq (Point 2 r :+ p) -> Polygon Simple p r

MultiPolygon :: CSeq (Point 2 r :+ p) -> [Polygon Simple p r] -> Polygon Multi p r

Instances

Bifunctor (Polygon t)

Defined in Data.Geometry.Polygon.Core

Methods

bimap :: (a -> b) -> (c -> d) -> Polygon t a c -> Polygon t b d

first :: (a -> b) -> Polygon t a c -> Polygon t b c

second :: (b -> c) -> Polygon t a b -> Polygon t a c

Bitraversable (Polygon t)

Defined in Data.Geometry.Polygon.Core

Methods

bitraverse :: Applicative f => (a -> f c) -> (b -> f d) -> Polygon t a b -> f (Polygon t c d)

Bifoldable (Polygon t)

Defined in Data.Geometry.Polygon.Core

Methods

bifold :: Monoid m => Polygon t m m -> m

bifoldMap :: Monoid m => (a -> m) -> (b -> m) -> Polygon t a b -> m

bifoldr :: (a -> c -> c) -> (b -> c -> c) -> c -> Polygon t a b -> c

bifoldl :: (c -> a -> c) -> (c -> b -> c) -> c -> Polygon t a b -> c

PointFunctor (Polygon t p)

Defined in Data.Geometry.Polygon.Core

Methods

pmap :: (Point (Dimension (Polygon t p r)) r -> Point (Dimension (Polygon t p s)) s) -> Polygon t p r -> Polygon t p s

(Fractional r, Ord r) => IsIntersectableWith (Point 2 r) (Polygon t p r)

Defined in Data.Geometry.Polygon.Core

Methods

intersect :: Point 2 r -> Polygon t p r -> Intersection (Point 2 r) (Polygon t p r)

intersects :: Point 2 r -> Polygon t p r -> Bool

nonEmptyIntersection :: proxy (Point 2 r) -> proxy (Polygon t p r) -> Intersection (Point 2 r) (Polygon t p r) -> Bool

(Eq p, Eq r) => Eq (Polygon t p r)

Defined in Data.Geometry.Polygon.Core

Methods

(==) :: Polygon t p r -> Polygon t p r -> Bool

(/=) :: Polygon t p r -> Polygon t p r -> Bool

(Show p, Show r) => Show (Polygon t p r)

Defined in Data.Geometry.Polygon.Core

Methods

showsPrec :: Int -> Polygon t p r -> ShowS

show :: Polygon t p r -> String

showList :: [Polygon t p r] -> ShowS

(NFData p, NFData r) => NFData (Polygon t p r)

Defined in Data.Geometry.Polygon.Core

Methods

rnf :: Polygon t p r -> ()

Fractional r => IsTransformable (Polygon t p r)

Defined in Data.Geometry.Polygon.Core

Methods

transformBy :: Transformation (Dimension (Polygon t p r)) (NumType (Polygon t p r)) -> Polygon t p r -> Polygon t p r

IsBoxable (Polygon t p r)

Defined in Data.Geometry.Polygon.Core

Methods

boundingBox :: Polygon t p r -> Box (Dimension (Polygon t p r)) () (NumType (Polygon t p r))

type NumType (SomePolygon p r)

Defined in Data.Geometry.Polygon.Core

type NumType (SomePolygon p r) = r

type Dimension (SomePolygon p r)

Defined in Data.Geometry.Polygon.Core

type Dimension (SomePolygon p r) = 2

type IntersectionOf (Line 2 r) (Boundary (Polygon t p r))

Defined in Data.Geometry.Polygon.Core

type IntersectionOf (Line 2 r) (Boundary (Polygon t p r)) = Seq (Either (Point 2 r) (LineSegment 2 () r)) ': ([] :: [Type])

type IntersectionOf (Point 2 r) (Polygon t p r)

Defined in Data.Geometry.Polygon.Core

type IntersectionOf (Point 2 r) (Polygon t p r) = NoIntersection ': (Point 2 r ': ([] :: [Type]))

type NumType (Polygon t p r)

Defined in Data.Geometry.Polygon.Core

type NumType (Polygon t p r) = r

type Dimension (Polygon t p r)

Polygons are per definition 2 dimensional

Defined in Data.Geometry.Polygon.Core

type Dimension (Polygon t p r) = 2

_SimplePolygon :: Prism' (Polygon Simple p r) (CSeq (Point 2 r :+ p))

Prism to test if we are a simple polygon

_MultiPolygon :: Prism' (Polygon Multi p r) (CSeq (Point 2 r :+ p), [Polygon Simple p r])

Prism to test if we are a Multi polygon

type SimplePolygon = Polygon Simple

type MultiPolygon = Polygon Multi

type SomePolygon p r = Either (Polygon Simple p r) (Polygon Multi p r)

Either a simple or multipolygon

fromPoints :: [Point 2 r :+ p] -> SimplePolygon p r

Creates a simple polygon from the given list of vertices.

pre: the input list constains no repeated vertices.

polygonVertices :: Polygon t p r -> NonEmpty (Point 2 r :+ p)

The vertices in the polygon. No guarantees are given on the order in which they appear!

listEdges :: Polygon t p r -> [LineSegment 2 p r]

Lists all edges. The edges on the outer boundary are given before the ones on the holes. However, no other guarantees are given on the order.

running time: \(O(n)\)

outerBoundary :: forall t p r. Lens' (Polygon t p r) (CSeq (Point 2 r :+ p))

outerBoundaryEdges :: Polygon t p r -> CSeq (LineSegment 2 p r)

The edges along the outer boundary of the polygon. The edges are half open.

running time: \(O(n)\)

outerVertex :: Int -> Lens' (Polygon t p r) (Point 2 r :+ p)

Access the i^th vertex on the outer boundary

outerBoundaryEdge :: Int -> Polygon t p r -> LineSegment 2 p r

polygonHoles :: forall p r. Lens' (Polygon Multi p r) [Polygon Simple p r]

polygonHoles' :: Traversal' (Polygon t p r) [Polygon Simple p r]

holeList :: Polygon t p r -> [Polygon Simple p r]

Get all holes in a polygon

inPolygon :: forall t p r. (Fractional r, Ord r) => Point 2 r -> Polygon t p r -> PointLocationResult

Check if a point lies inside a polygon, on the boundary, or outside of the polygon. Running time: O(n).

>>> Point2 1 1 `inPolygon` simplePoly
Inside
>>> Point2 0 0 `inPolygon` simplePoly
OnBoundary
>>> Point2 10 0 `inPolygon` simplePoly
OnBoundary
>>> Point2 5 13 `inPolygon` simplePoly
Inside
>>> Point2 5 10 `inPolygon` simplePoly
Inside
>>> Point2 10 5 `inPolygon` simplePoly
OnBoundary
>>> Point2 20 5 `inPolygon` simplePoly
Outside

TODO: Add some testcases with multiPolygons TODO: Add some more onBoundary testcases

insidePolygon :: (Fractional r, Ord r) => Point 2 r -> Polygon t p r -> Bool

Test if a point lies strictly inside the polgyon.

onBoundary :: (Fractional r, Ord r) => Point 2 r -> Polygon t p r -> Bool

Test if q lies on the boundary of the polygon. Running time: O(n)

>>> Point2 1 1 `onBoundary` simplePoly
False
>>> Point2 0 0 `onBoundary` simplePoly
True
>>> Point2 10 0 `onBoundary` simplePoly
True
>>> Point2 5 13 `onBoundary` simplePoly
False
>>> Point2 5 10 `onBoundary` simplePoly
False
>>> Point2 10 5 `onBoundary` simplePoly
True
>>> Point2 20 5 `onBoundary` simplePoly
False

TODO: testcases multipolygon

area :: Fractional r => Polygon t p r -> r

Compute the area of a polygon

signedArea :: Fractional r => SimplePolygon p r -> r

Compute the signed area of a simple polygon. The the vertices are in clockwise order, the signed area will be negative, if the verices are given in counter clockwise order, the area will be positive.

centroid :: Fractional r => SimplePolygon p r -> Point 2 r

Compute the centroid of a simple polygon.

pickPoint :: (Ord r, Fractional r) => Polygon p t r -> Point 2 r

Pick a point that is inside the polygon.

(note: if the polygon is degenerate; i.e. has <3 vertices, we report a vertex of the polygon instead.)

pre: the polygon is given in CCW order

running time: \(O(n)\)

isTriangle :: Polygon p t r -> Bool

Test if the polygon is a triangle

running time: \(O(1)\)

isStarShaped :: (MonadRandom m, Ord r, Fractional r) => SimplePolygon p r -> m (Maybe (Point 2 r))

Test if a Simple polygon is star-shaped. Returns a point in the kernel (i.e. from which the entire polygon is visible), if it exists.

\(O(n)\) expected time

isCounterClockwise :: (Eq r, Fractional r) => Polygon t p r -> Bool

Test if the outer boundary of the polygon is in clockwise or counter clockwise order.

running time: \(O(n)\)

toCounterClockWiseOrder :: (Eq r, Fractional r) => Polygon t p r -> Polygon t p r

Make sure that every edge has the polygon's interior on its left, by orienting the outer boundary into counter-clockwise order, and the inner borders (i.e. any holes, if they exist) into clockwise order.

running time: \(O(n)\)

toCounterClockWiseOrder' :: (Eq r, Fractional r) => Polygon t p r -> Polygon t p r

Orient the outer boundary into counter-clockwise order. Leaves any holes as they are.

toClockwiseOrder :: (Eq r, Fractional r) => Polygon t p r -> Polygon t p r

Make sure that every edge has the polygon's interior on its right, by orienting the outer boundary into clockwise order, and the inner borders (i.e. any holes, if they exist) into counter-clockwise order.

running time: \(O(n)\) | Orient the outer boundary of the polygon to clockwise order

toClockwiseOrder' :: (Eq r, Fractional r) => Polygon t p r -> Polygon t p r

Orient the outer boundary into clockwise order. Leaves any holes as they are.

reverseOuterBoundary :: Polygon t p r -> Polygon t p r

findDiagonal :: (Ord r, Fractional r) => Polygon t p r -> LineSegment 2 p r

Find a diagonal of the polygon.

pre: the polygon is given in CCW order

running time: \(O(n)\)

withIncidentEdges :: Polygon t p r -> Polygon t (Two (LineSegment 2 p r)) r

Pairs every vertex with its incident edges. The first one is its predecessor edge, the second one its successor edge (in terms of the ordering along the boundary).

>>> mapM_ print . polygonVertices $ withIncidentEdges simplePoly
Point2 [0,0] :+ V2 LineSegment (Closed (Point2 [1,11] :+ ())) (Closed (Point2 [0,0] :+ ())) LineSegment (Closed (Point2 [0,0] :+ ())) (Closed (Point2 [10,0] :+ ()))
Point2 [10,0] :+ V2 LineSegment (Closed (Point2 [0,0] :+ ())) (Closed (Point2 [10,0] :+ ())) LineSegment (Closed (Point2 [10,0] :+ ())) (Closed (Point2 [10,10] :+ ()))
Point2 [10,10] :+ V2 LineSegment (Closed (Point2 [10,0] :+ ())) (Closed (Point2 [10,10] :+ ())) LineSegment (Closed (Point2 [10,10] :+ ())) (Closed (Point2 [5,15] :+ ()))
Point2 [5,15] :+ V2 LineSegment (Closed (Point2 [10,10] :+ ())) (Closed (Point2 [5,15] :+ ())) LineSegment (Closed (Point2 [5,15] :+ ())) (Closed (Point2 [1,11] :+ ()))
Point2 [1,11] :+ V2 LineSegment (Closed (Point2 [5,15] :+ ())) (Closed (Point2 [1,11] :+ ())) LineSegment (Closed (Point2 [1,11] :+ ())) (Closed (Point2 [0,0] :+ ()))

numberVertices :: Polygon t p r -> Polygon t (SP Int p) r

assigns unique integer numbers to all vertices. Numbers start from 0, and are increasing along the outer boundary. The vertices of holes will be numbered last, in the same order.

>>> numberVertices simplePoly
SimplePolygon (CSeq [Point2 [0,0] :+ SP 0 (),Point2 [10,0] :+ SP 1 (),Point2 [10,10] :+ SP 2 (),Point2 [5,15] :+ SP 3 (),Point2 [1,11] :+ SP 4 ()])

asSimplePolygon :: Polygon t p r -> SimplePolygon p r

Convert a Polygon to a simple polygon by forgetting about any holes.

extremesLinear :: (Ord r, Num r) => Vector 2 r -> Polygon t p r -> (Point 2 r :+ p, Point 2 r :+ p)

Finds the extreme points, minimum and maximum, in a given direction

running time: \(O(n)\)

cmpExtreme :: (Num r, Ord r) => Vector 2 r -> (Point 2 r :+ p) -> (Point 2 r :+ q) -> Ordering

Comparison that compares which point is larger in the direction given by the vector u.