I represent a polygon that is defined by a sequence of vertices. Every vertex is connected to two other vertices.

	adding
	add: add:after: add:before: addAll: addLast:

	converting
	asEdgeList asSortedCollection normalizedWithin:

	enumerating
	do:

	geometry
	center length reverseCirculation

	point reduction
	normalizeTo: reduceTo:

	private
	assorts

	removing
	remove:

	testing
	circulation includes: is:connectedWith: isSimple

	accessing	top
	after:
	before:
	boundingBox
	bounds
	end
	nextButOne:
	size Primitive. Answer the number of indexable variables in the receiver. This value is the same as the largest legal subscript. Essential. See Object documentation whatIsAPrimitive.
	start
	vertices
	vertices:

	adding	top
	add:
	add:after:
	add:before:
	addAll:
	addLast:

	converting	top
	asEdgeList
	asSortedCollection Returns a SortedCollection of my vertices. The sort order is lexicographically. This can be used as an eventqueue for sweepline algorithms.
	normalizedWithin:

	enumerating	top
	do:

	geometry	top
	center
	length
	reverseCirculation

	point reduction	top
	normalizeTo:
	reduceTo:

	private	top
	assorts Builds a SortedCollection of my vertices. The sort order is lexicographically. This can be used as an eventqueue for sweepline algorithms.

	removing	top
	remove:

	testing	top
	circulation The circulation of a simple polygon can be #left (counterclockwise) or #right (clockwise)
	includes:
	is:connectedWith:
	isSimple | queue edges event prev next sleeve1 sleeve2 | queue _ self asSortedCollection removeLast; yourself. edges _ OrderedCollection new. [queue isEmpty] whileFalse: [event _ queue removeFirst. prev _ self before: event. next _ self after: event. sleeve1 _ prev x <= event x. sleeve2 _ next x <= event x. sleeve1 ifTrue: [edges remove: prev]. sleeve2 ifTrue: [edges remove: event]. sleeve1 ifFalse: [edges do: [:origin | ((origin to: (self after: origin) intersects: prev to: event) and: [prev ~= (self after: origin)]) ifTrue: [^ false]]]. sleeve2 ifFalse: [edges do: [:origin | ((origin to: (self after: origin) intersects: event to: next) and: [next ~= origin]) ifTrue: [^ false]]]. sleeve1 ifFalse: [edges add: prev]. sleeve2 ifFalse: [edges add: event]].

	examples	top
	testCircle SimplePolygon testCircle
	testFly SimplePolygon testFly
	testTriangle SimplePolygon testTriangle