Add support for masked triangulations

An example has also been added (adapted from tripcolor) to illustrate
the use of masked triangulations.

Author: dmcdougall

examples/mplot3d/trisurf3d_demo2.py

@@ -21,7 +21,36 @@
 
 # The triangles in parameter space determnine which x, y, z points are
 # connected by an edge
-ax.plot_trisurf(x, y, z, triangles=tri.triangles)
+ax.plot_trisurf(x, y, z, triangles=tri.triangles, cmap=plt.cm.Spectral)
 
 ax.set_zlim(-1, 1)
 plt.show()
+
+# First create the x and y coordinates of the points.
+n_angles = 36
+n_radii = 8
+min_radius = 0.25
+radii = np.linspace(min_radius, 0.95, n_radii)
+
+angles = np.linspace(0, 2*np.pi, n_angles, endpoint=False)
+angles = np.repeat(angles[...,np.newaxis], n_radii, axis=1)
+angles[:,1::2] += np.pi/n_angles
+
+x = (radii*np.cos(angles)).flatten()
+y = (radii*np.sin(angles)).flatten()
+z = (np.cos(radii)*np.cos(angles*3.0)).flatten()
+
+# Create the Triangulation; no triangles so Delaunay triangulation created.
+triang = mtri.Triangulation(x, y)
+
+# Mask off unwanted triangles.
+xmid = x[triang.triangles].mean(axis=1)
+ymid = y[triang.triangles].mean(axis=1)
+mask = np.where(xmid*xmid + ymid*ymid < min_radius*min_radius, 1, 0)
+triang.set_mask(mask)
+
+# tripcolor plot.
+fig = plt.figure()
+ax = fig.add_subplot(1, 1, 1, projection='3d')
+ax.plot_trisurf(triang, z, cmap=plt.cm.CMRmap)
+plt.show()

lib/mpl_toolkits/mplot3d/axes3d.py

@@ -1628,7 +1628,7 @@ def plot_trisurf(self, *args, **kwargs):
         z = np.asarray(args[0])
 
         # TODO: Support masked triangulations
-        triangles = tri.triangles
+        triangles = tri.get_masked_triangles()
         xt = tri.x[triangles][...,np.newaxis]
         yt = tri.y[triangles][...,np.newaxis]
         zt = np.array(z)[triangles][...,np.newaxis]