cornu spiral for course banners

cornu.R

library(ggplot2)
library(pracma)
library(ggplot2)
# remotes::install_github('houyunhuang/ggvwline')
library(grid)
library(vwline)
library(gggrid)

bump <- function(t) ifelse(abs(t)<1, exp(-1/(1-t^2)), 0)
cornu <- function(q){
  
  data.frame(x=fresnelS(q) , 
             y=fresnelC(q),
             t=q,f=0.03+0.2*bump(t)+0.5*bump(t+0.2)+0.31*bump(t*2-3.2))
  
}


t <- seq(-0.92*pi,0.92*pi,length=600)
y <- cornu(t)

ggplot(y,aes(x,y,size=12*f/10)) +
  theme_void() +
  geom_path(col='gold') +
  theme(legend.position = 'none')

ggsave('cornu.png')

last_plot() + coord_polar(theta = 'y') 
ggsave('cornu-polar.png')