vrp-plot helpers

helpers.r

plottitle <- function(t){
  ### Plot "Folie ###"
  plot(NA,NA,frame.plot=FALSE, xlab="", ylab="", xlim= c(-1,1), ylim=c(-1,1), axes=FALSE)
  text(0,0,t, cex=2, )
}


getPolar <- function(n0,n1){
  # Polarwinkel berechnung zum vekürzen der Pfeile     
  x1 <- n1$x
  x0 <- n0$x
  y1 <- n1$y
  y0 <- n0$y
  value<-NULL
    
  x<-x1-x0
  y<-y1-y0
  if(x==0){
    if(y>0){
      value<-pi/2
    }else{
      if(y<0){
        value<- 3*pi/2
      }else{
        # warning("Angle can't be calculated because both coordinates are the same. Returning NA.")
        return(NA)
      }
    }
  }else{
    value<-atan(y/x)
    if(x<0){
      value<-value+pi
    } 
  }  
  return(value)
} 

getNewPoint <- function(p1, p2, short){
  # verkürzen der Pfeile damit es "hübscher aussieht"
  m <- getPolar(p1,p2)
  if(is.na(m)){
    return(NA)
  }else{
    r <- sqrt((p1$x - p2$x )^2 + (p1$y - p2$y)^2)
    
    x <- p1$x + (r - short) * cos(m)  
    y <- p1$y + (r - short) * sin(m) 
    
    return (data.frame(x=x, y=y))
  }
}