[Matplotlib-users] Matplotlib - Drawing a Trapezoid Isosceles with Poly3DCollection

[<cl...@br...>]

Dear colleagues, 

 Exploring the 3D support for plotting a simple trapezoid isosceles based 
on eight locations with x,y,z (imagine a water tank). When doing a manual 
selection of the collections that defines each surface plane, the drawing 
works well (see a sample below). Watching for a more automated process 
that could work with a complex surface based on any Polygons. 

My question: Is there an algorithm, or function in Numpy or Matplotlib 
that identifies the quartet of each plane in the sample below?  I've tried 
to apply Numpy function "combinations", but it generates too many 
collections. 

Thanks in advance for your hint to optimize this drawing with the 
Matplotlib with Poly3DCollection

Sample Code
-----------
from mpl_toolkits.mplot3d import Axes3D
from mpl_toolkits.mplot3d.art3d import Poly3DCollection
from mpl_toolkits.mplot3d.art3d import Line3DCollection
import matplotlib.pyplot as plt
from matplotlib import cm
import matplotlib.colors as colors
from numpy import random
fig = plt.figure()
ax = Axes3D(fig)
# for random color settings
color = colors.rgb2hex(random.rand(3))
# blue color
color = 'b'
#mypoly = [[2, 0, -1], [2, 0, 1], [4, 0, 1], [4, 0, -1],  [0, 4, -2], [0, 
4, 2], [6, 4, 2], [6, 4, -2]]
#               A           B          C          D            E F  G  H
# Colections for drawing 3D plot with polygon  (each plane defined 
separately)
#plane a: A,E,H,D
#plane b: A,E,F,B
#plane c: B,F,G,C
#plane d: C,G,H,D 
#plane e: E,F,G,H
#plane f: A,B,C,D 
#plane collection 
xa = [2,0,6,4] 
ya = [0,4,4,0]
za = [-1,-2,-2,-1]
#second collection
xb = [2,0,0,2] 
yb = [0,4,4,0]
zb = [-1,-2,2,1]
#third collection
xc = [2,0,6,4] 
yc = [0,4,4,0]
zc = [1,2,2,1]
#fourth collection
xd = [4,6,6,4] 
yd = [0,4,4,0]
zd = [1,2,-2,-1]
#fifth collection (kept open, to watch the plot result)
xe = [0,0,6,6] 
ye = [4,4,4,4]
ze = [-2,2,2,-2]
#sixth collection 
xf = [2,2,4,4] 
yf = [0,0,0,0]
zf = [-1,1,1,-1]
# to do
verts = [zip(xa, ya,za),zip(xb, yb,zb),zip(xc, yc,zc),zip(xd, 
yd,zd),zip(xf, yf,zf)]
ax.add_collection3d(Poly3DCollection(verts, facecolors=color, 
linewidths=1, alpha=0.5))
ax.add_collection3d(Line3DCollection(verts, colors='k', linewidths=0.2, 
linestyles=':'))
# set axis view
# add grid
ax.grid(True)
# view
ax.set_xlim(-1,6)
ax.set_ylim(-1,6)
ax.set_zlim(-5,5)
ax.view_init(elev=10., azim=110.)
ax.get_xaxis().set_visible(True)
ax.get_yaxis().set_visible(True)
ax.set_autoscale_on(True)
plt.show()

Thanks for support. 

Regards, 
Claude 



Claude Falbriard 
Certified IT Specialist L2 - Middleware
AMS Hortolândia / SP - Brazil
phone:    +55 13 9 9760 0453
cell:         +55 13 9 8117 3316
e-mail:    cl...@br...