Drawing lines in raster cells (in R), with application to species distribution mapping

I guess we all had this demand from one of our tutor saying: “look at this nice output a previous intern did, well I’d like you to do the same”. In my case the previous intern was using a different software so I had to find a way to implement it… The task was to draw lines on maps representing the area where certain species are distributed and to change the angle of the lines for different times. Here is one way to do this in R:

http://rpubs.com/Lionel/6136