33import matplotlib .pyplot as plt
44
55from matplotlib .backend_bases import MouseEvent
6- from mpl_toolkits .mplot3d .art3d import Line3DCollection
6+ from mpl_toolkits .mplot3d .art3d import Line3DCollection , Poly3DCollection
77
88
99def test_scatter_3d_projection_conservation ():
@@ -54,3 +54,32 @@ def test_zordered_error():
5454 ax .add_collection (Line3DCollection (lc ))
5555 ax .scatter (* pc , visible = False )
5656 plt .draw ()
57+
58+
59+ def test_generate_normals ():
60+
61+ # Following code is an example taken from
62+ # https://stackoverflow.com/questions/18897786/transparency-for-poly3dcollection-plot-in-matplotlib
63+ # and modified to test _generate_normals function
64+
65+ fig = plt .figure ()
66+ ax = fig .add_subplot (111 , projection = '3d' )
67+
68+ x = [0 , 2 , 1 , 1 ]
69+ y = [0 , 0 , 1 , 0 ]
70+ z = [0 , 0 , 0 , 1 ]
71+
72+ # deliberately use nested tuple
73+ vertices = ((0 , 1 , 2 ), (0 , 1 , 3 ), (0 , 2 , 3 ), (1 , 2 , 3 ))
74+
75+ tupleList = list (zip (x , y , z ))
76+
77+ poly3d = [[tupleList [vertices [ix ][iy ]] for iy in range (len (vertices [0 ]))]
78+ for ix in range (len (vertices ))]
79+ ax .scatter (x , y , z )
80+ collection = Poly3DCollection (poly3d , alpha = 0.2 , edgecolors = 'r' , shade = True )
81+ face_color = [0.5 , 0.5 , 1 ] # alternative: matplotlib.colors.rgb2hex([0.5, 0.5, 1])
82+ collection .set_facecolor (face_color )
83+ ax .add_collection3d (collection )
84+
85+ plt .draw ()
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