Usuários, gostaria de ter algumas dicas para um ternário ("vcd").

Eu tenho esse dataframe:

a <- c(0.1, 0.5, 0.5, 0.6, 0.2, 0, 0, 0.004166667, 0.45) 
b <- c(0.75,0.5,0,0.1,0.2,0.951612903,0.918103448,0.7875,0.45)
c <- c(0.15,0,0.5,0.3,0.6,0.048387097,0.081896552,0.208333333,0.1) 
d <- c(500,2324.90,2551.44,1244.50, 551.22,-644.20,-377.17,-100, 2493.04) 
df <- data.frame(a, b, c, d)

e estou construindo um enredo ternário:

ternaryplot(df[,1:3], df$d)

Como posso mapear a variável contínuad, obtendo um resultado semelhante a este?