createPolygonFor: each
	"create the background polygon shape if the variable #shouldUseEllipse equals False.
	
	The polygon must be created with a rotation if the number of axis is even."

	| rotation |
	rotation := 0.
	axisNames size even ifTrue: [ rotation := Float pi / axisNames size ].

	^ RSPolygon new
		  noPaint;
		  points:
			  (RSPolygon
				   generateUnitNgonPoints: axisNames size
				   rotation: rotation) * each;
		  border: self border;
		  yourself

fixLabelPosition: label angle: angle

	| positions gap |
	label position: angle cos @ angle sin * radius.
	gap := self labelGapSize.
	positions := Dictionary newFromPairs: {
			             0.
			             (0.5 @ 0).
				     Float halfPi.
			             (0 @ 0.5).
			             Float halfPi negated.
			             (0 @ -0.5).
			             Float pi.
			             (-0.5 @ 0).
			             (Float pi + Float halfPi).
			             (0 @ 0.5) }.
	positions
		at: angle
		ifPresent: [ :fix |
		label translateBy: label extent * fix + (gap * fix sign) ]
		ifAbsent: [
			gap := angle cos @ angle sin * gap.
			(angle between: Float halfPi negated and: 0) ifTrue: [
				^ label translateBy: label baseRectangle bottomLeft negated + gap ].
			(angle between: 0 and: Float halfPi) ifTrue: [
				^ label translateBy: label baseRectangle topLeft negated + gap ].
			(angle between: Float halfPi and: Float pi) ifTrue: [
				^ label translateBy: label baseRectangle topRight negated + gap ].
			label translateBy: label baseRectangle bottomRight negated + gap ]

 Float halfPi ->  (0 @ 0.5).