polygon-circle ( n diameter -- vertices )

Vocabulary

ui.pens.polygon

Inputs

n	an integer
diameter	a real

Outputs

vertices

a matrix

Word description

Approximates the vertices of a circle as a polygon with n amount of points.

USING: sequences math.vectors ui.gadgets.grids ui.gadgets.panes ui.theme ; 9 <iota> 3 v+n [ 20 polygon-circle details-color swap <polygon-gadget> ] map 1array <grid> gadget.

Definition

USING: arrays kernel math math.constants math.functions
sequences ;

IN: ui.pens.polygon

:: polygon-circle ( n diameter -- vertices )
    n 1 + <iota> [ 2 pi * * n / [ sin ] [ cos ] bi 2array ] map
    diameter 2 / [ [ * ] [ + ] bi round >fixnum ] curry
    [ map ] curry map ;