ENH: Set the default plotbox aspect to match how renders looked previously

eric-wieser · eric-wieser · commit c3e7c48dd022 · 2020-02-11T16:17:37.000Z
This sets it to have a 4:3 aspect ratio, which matches what would result from a typical figure layout
diff --git a/lib/mpl_toolkits/mplot3d/axes3d.py b/lib/mpl_toolkits/mplot3d/axes3d.py
@@ -964,6 +964,9 @@ def get_proj(self):
 
         dist is the distance of the eye viewing point from the object point.
         """
+        # chosen for similarity with the initial view before gh-8896
+        pb_aspect = np.array([4, 4, 3]) / 3.5
+
         relev, razim = np.pi * self.elev/180, np.pi * self.azim/180
 
         xmin, xmax = self.get_xlim3d()
@@ -973,10 +976,10 @@ def get_proj(self):
         # transform to uniform world coordinates 0-1, 0-1, 0-1
         worldM = proj3d.world_transformation(xmin, xmax,
                                              ymin, ymax,
-                                             zmin, zmax)
+                                             zmin, zmax, pb_aspect=pb_aspect)
 
         # look into the middle of the new coordinates
-        R = np.array([0.5, 0.5, 0.5])
+        R = pb_aspect / 2
 
         xp = R[0] + np.cos(razim) * np.cos(relev) * self.dist
         yp = R[1] + np.sin(razim) * np.cos(relev) * self.dist
diff --git a/lib/mpl_toolkits/mplot3d/proj3d.py b/lib/mpl_toolkits/mplot3d/proj3d.py
@@ -30,8 +30,20 @@ def _line2d_seg_dist(p1, p2, p0):
 
 def world_transformation(xmin, xmax,
                          ymin, ymax,
-                         zmin, zmax):
-    dx, dy, dz = (xmax-xmin), (ymax-ymin), (zmax-zmin)
+                         zmin, zmax, pb_aspect=None):
+    """
+    produce a matrix that scales homogenous coords in the specified ranges
+    to [0, 1], or [0, pb_aspect[i]] if the plotbox aspect ratio is specified
+    """
+    dx = xmax - xmin
+    dy = ymax - ymin
+    dz = zmax - zmin
+    if pb_aspect is not None:
+        ax, ay, az = pb_aspect
+        dx /= ax
+        dy /= ay
+        dz /= az
+
     return np.array([[1/dx, 0,    0,    -xmin/dx],
                      [0,    1/dy, 0,    -ymin/dy],
                      [0,    0,    1/dz, -zmin/dz],
