Opacity/alpha as attribute linked to a continuous variable

I am trying to get a continuous transparency according to a continuous variable that also defines the color. I've tried the code suggested in this post https://github.com/ropensci/plotly/issues/389 but I dont manage to do what I want and, in fact, I get very unexpected plots since the colorbar and marker's colors do not match + transparency seems the same for all colors.

require(plotly)
plot_ly(x = rnorm(100), y = rnorm(100), z = rnorm(100),
color = rbeta(100,shape1=1,shape2=1),alpha=.2,
type = "scatter3d", mode= "markers",
colors=colorRamp(c("blue","red")))

I'd like to get low transparency at high color values and vice versa. Is this possible in the currrent version of plot_ly?

plot_ly(x = rnorm(100), y = rnorm(100), z = rnorm(100),
color = rbeta(100,shape1=1,shape2=1),opacity=.2,
type = "scatter3d", mode= "markers",
colors=colorRamp(c("blue","red")))

setting opacity instead of alpha seems to fix the colouring vs colorbar but not the transparency issue.

Comienza con los ejemplos reproducibles de scatter3d de plot_ly en el issue e investiga cómo se asignan el color, el alpha y la opacidad a los marcadores. Verifica el comportamiento con la colorbar y la apariencia de los marcadores; se considera terminado cuando una variable continua puede controlar tanto el color como la transparencia según lo solicitado, sin que los colores no coincidan.