Highcharts/HighcharteR - draw a polygon with rounded corners - highcharts

Question

library(highcharter)
highchart() %>%
hc_add_series(name='Polygon',type='polygon',data=list(c(1,4),c(2,4), c(3,3), c(2,3)),
borderRadius = 10, lineColor = "red", lineWidth = 3)][1]][1]
Hello everybody. I use a polygon to display some data. I would prefer to have the borders to be round, but the borderRadius attribute does not work for the polygon.
Does anyone have an idea how to archieve a rounded look of my polygon? Documentation did not help in this case :-(. This is made the the R Highcharter package, but I would also be totally fine with an example in die native JS Library.
Thank you!

Answer 1

This works somewhat:
spline.poly <- function(xy, vertices, k=3, ...) {
# Assert: xy is an n by 2 matrix with n >= k.
# Wrap k vertices around each end.
n <- dim(xy)[1]
if (k >= 1) {
data <- rbind(xy[(n-k+1):n,], xy, xy[1:k, ])
} else {
data <- xy
}
# Spline the x and y coordinates.
data.spline <- spline(1:(n+2*k), data[,1], n=vertices, ...)
x <- data.spline$x
x1 <- data.spline$y
x2 <- spline(1:(n+2*k), data[,2], n=vertices, ...)$y
# Retain only the middle part.
cbind(x1, x2)[k < x & x <= n+k, ]
}
X <- matrix(c(resultdf$yAxis, resultdf$xAxis), ncol=2)
hpts <- chull(X) # Creates indices of a convex hull from a matrix
hpts <- c(hpts, hpts[1]) # connect last and first dot
hpts <- data.frame(X[hpts, ])
hpts <- data.frame(spline.poly(as.matrix(data.frame(hpts$X1, hpts$X2)), 500)) %>%
setNames(c("yAxis", "xAxis"))
the spline.poly function creates a lot of new points which connect to a more rounded shape :-)