Set The Ternary Arrow Baseline

#Create plot object
plot <- ggtern(data=data.frame(x=1,y=1,z=1),mapping=aes(x,y,z)) +
  geom_point() + theme_rgbw() +
  tern_limits(labels=c(10,20,"","","","","",80,90,100),
             breaks=seq(0.1,1,by=0.1)) +
  theme(axis.tern.arrowstart=0.25,axis.tern.arrowfinish=0.75) +
  theme_ticksoutside() +
  #to illustrate the actual origin, set arrowsep to zero
  theme(axis.tern.arrowsep=unit(0,"npc"))

 #Default behaviour
 plot + theme_arrowbaseline(0)

##Alternatives, Uncomment below
 #plot + theme_arrowbaseline(1)
 #plot + theme_arrowbaseline(2)
 #plot + theme_arrowbaseline("axis")
 #plot + theme_arrowbaseline("ticks")
 #plot + theme_arrowbaseline("labels")