Hi,

I'm trying to do a 3D plot with semi-transparent polyhedrons using mplot3d, but the setting of the alpha value has no effect. Here's the code I'm trying,

import mpl_toolkits.mplot3d as a3
import matplotlib.colors as colors
import pylab as pl

ax = a3.Axes3D(pl.figure())

color = colors.rgb2hex(sp.rand(3))

color = (0.,1.,0.,0.2) # but this works!

side1 = [[0.,0.,0.],[0.,0.,1.],[0.,1.,1.],[0.,1.,0.]]
tri = a3.art3d.Poly3DCollection([side1])
tri.set_facecolor(color)
tri.set_edgecolor('k')
tri.set_alpha(0.2) # HAS NO EFFECT

ax.add_collection3d(tri)

side2 = [[0.,0.,0.],[1.,0.,0.],[1.,1.,0.],[0.,1.,0.]]
tri = a3.art3d.Poly3DCollection([side2])
tri.set_facecolor(color)
tri.set_edgecolor('k')
tri.set_alpha(0.2)

ax.add_collection3d(tri)

pl.show()

Apparently, the tri.set_alpha sentences have no effect, and the pannels show solid. Changing color for an rgba tupla works, nonetheless (the commented line).

Cheers,

Ruyman