polygon.R

polygon <- function(n) {
  tibble(
    x    = accumulate(1:(n-1), ~.x+cos(.y*2*pi/n), .init = 0),
    y    = accumulate(1:(n-1), ~.x+sin(.y*2*pi/n), .init = 0),
    xend = accumulate(2:n,     ~.x+cos(.y*2*pi/n), .init = cos(2*pi/n)),
    yend = accumulate(2:n,     ~.x+sin(.y*2*pi/n), .init = sin(2*pi/n)))
}

ggplot(polygon(5) + geom_segment(aes(x=x, y=y, xend=xend, yend=yend)) + theme_void() + coord_equal()