pie-slice

Divide circle into slices and tell what slice a point is in.

Install

npm install pie-slice --save

Usage

var pieSlice = require('pie-slice')
 
var slices = pieSlice.slice(4)
var ref = {x: 0, y: 0}
 
slices.whatSlice(ref, {x: 1, y: 1})   // => 1
slices.whatSlice(ref, {x: -1, y: -1}) // => 2

pieSlice.slice(sliceCount, [options])

sliceCount

Must be Number between 2 and 360, inclusive.

options

Object that may contain:

firstSliceFacesUp

(default: false)

When false the first slice starts at angle 0.

pieSlice.slice(4, {
  firstSliceFacesUp: false
})
 
// or just
 
pieSlice.slice(4)

When true first slice is bissected by angle 0.

pieSlice.slice(4, {
  firstSliceFacesUp: true
});

yDown

(default: false)

When true, points are interpretted based on y-down coordinates. In y-down coordinates the y values increase going downward.

When false, uses y-up coordinates. In y-up coordinates the y values increase going upward.

Returns

Slices of a pie.

slices.whatSlice(referencePoint, otherPoint)

referencePoint

Object with x and y Number properties. Treated as center of the sliced pie.

otherPoint

Object with x and y Number properties.

Returns

Number between 0 and sliceCount - 1 that is the answer to: if referencePoint is center of pie, what slice is otherPoint in?

Slice numbers increase going clockwise.

License

MIT