Align rotation of 3D plot by mouse with rolled axes

scottshambaugh · scottshambaugh · commit fd8f2397eca4 · 2021-10-22T00:30:25.000-06:00
diff --git a/lib/mpl_toolkits/mplot3d/axes3d.py b/lib/mpl_toolkits/mplot3d/axes3d.py
@@ -1267,10 +1267,13 @@ def _on_move(self, event):
         if self.button_pressed in self._rotate_btn:
             # rotate viewing point
             # get the x and y pixel coords
+            roll = np.deg2rad(self.roll)
             if dx == 0 and dy == 0:
                 return
-            self.elev = art3d._norm_angle(self.elev - (dy/h)*180)
-            self.azim = art3d._norm_angle(self.azim - (dx/w)*180)
+            delev =  (dy/h)*180*np.cos(roll) + (dx/w)*180*np.sin(roll)
+            dazim = -(dy/h)*180*np.sin(roll) + (dx/w)*180*np.cos(roll)
+            self.elev = art3d._norm_angle(self.elev - delev)
+            self.azim = art3d._norm_angle(self.azim - dazim)
             self.get_proj()
             self.stale = True
             self.figure.canvas.draw_idle()
@@ -1285,7 +1288,6 @@ def _on_move(self, event):
             dy = 1-((h - dy)/h)
             elev = np.deg2rad(self.elev)
             azim = np.deg2rad(self.azim)
-            roll = np.deg2rad(self.roll)
             # project xv, yv, zv -> xw, yw, zw
             dxx = (maxx-minx)*(dy*np.sin(elev)*np.cos(azim) + dx*np.sin(azim))
             dyy = (maxy-miny)*(-dx*np.cos(azim) + dy*np.sin(elev)*np.sin(azim))
