Fix 3d hover coordinates with scaled axes

scottshambaugh · scottshambaugh · commit d46c5df16488 · 2026-03-04T16:03:58.000-07:00
diff --git a/lib/mpl_toolkits/mplot3d/axes3d.py b/lib/mpl_toolkits/mplot3d/axes3d.py
@@ -1653,7 +1653,7 @@ def _location_coords(self, xv, yv, renderer):
 
     def _get_camera_loc(self):
         """
-        Returns the current camera location in data coordinates.
+        Returns the current camera location in transformed coordinates.
         """
         cx, cy, cz, dx, dy, dz = self._get_w_centers_ranges()
         c = np.array([cx, cy, cz])
@@ -1677,42 +1677,32 @@ def _calc_coord(self, xv, yv, renderer=None):
         else:  # perspective projection
             zv = -1 / self._focal_length
 
-        # Convert point on view plane to transformed coordinates
-        # (inv_transform returns scaled coords because M was built with scaled limits)
         p1 = np.array(proj3d.inv_transform(xv, yv, zv, self.invM)).ravel()
 
         # Get the vector from the camera to the point on the view plane
-        # Camera location is in data space, so transform it to transformed coordinates
-        cam_data = self._get_camera_loc()
-        cam_scaled = np.array(art3d._apply_scale_transforms(
-            cam_data[0], cam_data[1], cam_data[2], self)).ravel()
-        vec = cam_scaled - p1
-
-        # Get the pane locations for each of the axes in data space
-        # and transform to transformed coordinates
+        vec = self._get_camera_loc() - p1
+
+        # Get the pane locations for each of the axes
         pane_locs_data = []
         for axis in self._axis_map.values():
             xys, loc = axis.active_pane()
             pane_locs_data.append(loc)
-        pane_locs_scaled = np.array(art3d._apply_scale_transforms(
-            pane_locs_data[0], pane_locs_data[1], pane_locs_data[2], self)).ravel()
 
         # Find the distance to the nearest pane by projecting the view vector
         scales = np.zeros(3)
         for i in range(3):
             if vec[i] == 0:
                 scales[i] = np.inf
             else:
-                scales[i] = (p1[i] - pane_locs_scaled[i]) / vec[i]
+                scales[i] = (pane_locs_data[i] - p1[i]) / vec[i]
         pane_idx = np.argmin(abs(scales))
         scale = scales[pane_idx]
 
-        # Calculate the point on the closest pane in transformed coordinates
-        p2_scaled = p1 - scale*vec
+        # Calculate the point on the closest pane
+        p2 = p1 + scale * vec
 
-        # Convert back to data coordinates
-        p2 = np.array(self._untransform_point(
-            p2_scaled[0], p2_scaled[1], p2_scaled[2]))
+        # Convert from transformed to data coordinates
+        p2 = np.array(self._untransform_point(p2[0], p2[1], p2[2]))
         return p2, pane_idx
 
     def _arcball(self, x: float, y: float) -> np.ndarray:
diff --git a/lib/mpl_toolkits/mplot3d/tests/test_axes3d.py b/lib/mpl_toolkits/mplot3d/tests/test_axes3d.py
@@ -3171,3 +3171,17 @@ def test_scale3d_autoscale_with_log():
                       ('z', ax.get_zlim())]:
         assert lim[0] > 0, f"{name} lower limit should be positive"
         assert lim[1] > 0, f"{name} upper limit should be positive"
+
+
+def test_scale3d_calc_coord():
+    """_calc_coord should return data coordinates with correct pane values."""
+    fig = plt.figure()
+    ax = fig.add_subplot(projection='3d')
+    ax.scatter([1, 10, 100], [1, 10, 100], [1, 10, 100])
+    ax.set(xscale='log', yscale='log', zscale='log')
+    fig.canvas.draw()
+
+    point, pane_idx = ax._calc_coord(0.5, 0.5)
+    # Pane coordinate should match axis limit (y-pane at max)
+    assert pane_idx == 1
+    assert point[pane_idx] == pytest.approx(ax.get_ylim()[1])
