isometric cube for axes3d

Author: neok-m4700

lib/matplotlib/rcsetup.py

@@ -1190,6 +1190,7 @@ def _convert_validator_spec(key, conv):
     "axes.autolimit_mode": ["data", "round_numbers"],
     "axes.xmargin": _range_validators["0 <= x <= 1"],  # margin added to xaxis
     "axes.ymargin": _range_validators["0 <= x <= 1"],  # margin added to yaxis
+    'axes.zmargin': _range_validators["0 <= x <= 1"],  # margin added to zaxis
 
     "polaraxes.grid": validate_bool,  # display polar grid or not
     "axes3d.grid":    validate_bool,  # display 3d grid

lib/mpl_toolkits/mplot3d/axes3d.py

@@ -1178,7 +1178,10 @@ def cla(self):
                 pass
 
         self._autoscaleZon = True
-        self._zmargin = 0
+        if self._projection is proj3d.ortho_transformation:
+            self._zmargin = rcParams['axes.zmargin']
+        else:
+            self._zmargin = 0.
 
         self.grid(rcParams['axes3d.grid'])
 

lib/mpl_toolkits/tests/baseline_images/test_mplot3d/axes3d_isometric.png

@@ -947,6 +947,22 @@ def test_axes3d_ortho():
     ax.set_proj_type('ortho')
 
 
+@mpl3d_image_comparison(['axes3d_isometric.png'])
+def test_axes3d_isometric():
+    from itertools import combinations, product
+    fig, ax = plt.subplots(subplot_kw=dict(
+        projection='3d',
+        proj_type='ortho',
+        box_aspect=(4, 4, 4)
+    ))
+    r = (-1, 1)  # stackoverflow.com/a/11156353
+    for s, e in combinations(np.array(list(product(r, r, r))), 2):
+        if abs(s - e).sum() == r[1] - r[0]:
+            ax.plot3D(*zip(s, e), c='k')
+    ax.view_init(elev=np.degrees(np.arctan(1. / np.sqrt(2))), azim=-45)
+    ax.grid(True)
+
+
 @pytest.mark.parametrize('value', [np.inf, np.nan])
 @pytest.mark.parametrize(('setter', 'side'), [
     ('set_xlim3d', 'left'),

lib/mpl_toolkits/tests/test_mplot3d.py

@@ -417,6 +417,7 @@
                   # for more details on prop_cycle usage.
 #axes.xmargin:   .05  # x margin.  See `axes.Axes.margins`
 #axes.ymargin:   .05  # y margin.  See `axes.Axes.margins`
+#axes.zmargin:   .05  # z margin.  See `axes.Axes.margins`
 #axes.autolimit_mode: data  # If "data", use axes.xmargin and axes.ymargin as is.
                             # If "round_numbers", after application of margins, axis
                             # limits are further expanded to the nearest "round" number.