Add a continuous color ramp legend to a 3d scatter plot

I have two follow-up questions:

1. If I want to reverse the heat.colors (i.e., from yellow to red 
instead of red to yellow), is there a way to do that?

2. I also created this interactive 3d scatter plot as below:

library(rgl)
plot3d(x=x, y=y, z=z, col=nbcol[zcol], box=FALSE)

Is there any way to add the same legend to this 3d plot?

I'm new to R and try to learn it. I'm very grateful for any help!

thanks,
Z