Merge branch 'stable-matplotlib-3.4-deprecation-backport' into 'stable'

Backport Matplotlib fixes from master

See merge request kwant/kwant!395

kwant/_plotter.py

@@ -156,7 +156,7 @@ if mpl_available:
             def set_linewidths(self, linewidths):
                 self.linewidths_orig = nparray_if_array(linewidths)
 
-            def do_3d_projection(self, renderer):
+            def do_3d_projection(self, renderer=None):
                 super().do_3d_projection(renderer)
                 # The whole 3D ordering is flawed in mplot3d when several
                 # collections are added. We just use normal zorder. Note the
@@ -192,6 +192,10 @@ if mpl_available:
                 if offsets is not None:
                     kwargs['offsets'] = offsets[:, :2]
 
+                # Workaround for issue in Matplotlib-3.4.2 before PR merged
+                # https://github.com/matplotlib/matplotlib/pull/20416
+                self._z_markers_idx = slice(-1)
+
                 super().__init__(paths, **kwargs)
 
                 if offsets is not None:
@@ -243,7 +247,7 @@ if mpl_available:
                 else:
                     return Affine2D().scale(self.figure.dpi / 72.0)
 
-            def do_3d_projection(self, renderer):
+            def do_3d_projection(self, renderer=None):
                 xs, ys, zs = self._offsets3d
 
                 # numpy complains about zero-length index arrays
@@ -251,7 +255,7 @@ if mpl_available:
                     return -self.zorder3d
 
                 proj = mplot3d.proj3d.proj_transform_clip
-                vs = np.array(proj(xs, ys, zs, renderer.M)[:3])
+                vs = np.array(proj(xs, ys, zs, self.axes.M)[:3])
 
                 if sort3d:
                     indx = vs[2].argsort()[::-1]
@@ -307,7 +311,7 @@ if mpl_available:
                 bbox = np.asarray(self.axes.get_w_lims())
 
                 proj = mplot3d.proj3d.proj_transform_clip
-                cz = proj(*(list(np.dot(corners, bbox)) + [renderer.M]))[2]
+                cz = proj(*(list(np.dot(corners, bbox)) + [self.axes.M]))[2]
 
                 return -self.zorder3d + vs[2].mean() / cz.ptp()