Is object data, as accessed by Python, not committed until you exit edit mode?

Question

I am trying to understand accessing object data from Python, in particular vertex data. In this simple test:

• Make a new Blender document

• In the scripting interface, make a function to display vertex information (as suggested here):

  def showvertices():
    for item in bpy.data.objects:
      print(item.name)
      if item.type == 'MESH':
        for vertex in item.data.vertices:
          print(vertex.co)
  

• Now, typing in showvertices() in the Python console seems to display the correct information for the default cube:

  Camera
  Cube
  <Vector (-1.0000, -1.0000, -1.0000)>
  <Vector (-1.0000, -1.0000, 1.0000)>
  <Vector (-1.0000, 1.0000, -1.0000)>
  <Vector (-1.0000, 1.0000, 1.0000)>
  <Vector (1.0000, -1.0000, -1.0000)>
  <Vector (1.0000, -1.0000, 1.0000)>
  <Vector (1.0000, 1.0000, -1.0000)>
  <Vector (1.0000, 1.0000, 1.0000)>
  Light
  

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So far, so good. Now type:

• Tab -> enter edit mode
• A -> select all
• GX2 (Enter) -> move all vertices 2 units in the X direction

This appears to work, the cube moves to the right (from the front view) and the X coordinate of the top-right vertex is shown as 3m instead of 1m as it was before:

However, typing in showvertices() in the Python console still displays the original information, not the updated positions:

Camera
Cube
<Vector (-1.0000, -1.0000, -1.0000)>
<Vector (-1.0000, -1.0000, 1.0000)>
<Vector (-1.0000, 1.0000, -1.0000)>
<Vector (-1.0000, 1.0000, 1.0000)>
<Vector (1.0000, -1.0000, -1.0000)>
<Vector (1.0000, -1.0000, 1.0000)>
<Vector (1.0000, 1.0000, -1.0000)>
<Vector (1.0000, 1.0000, 1.0000)>
Light

Now if I press Tab to go back to Object mode and type in showvertices() again in the console, the vertex information is now updated:

Camera
Cube
<Vector (1.0000, -1.0000, -1.0000)>
<Vector (1.0000, -1.0000, 1.0000)>
<Vector (1.0000, 1.0000, -1.0000)>
<Vector (1.0000, 1.0000, 1.0000)>
<Vector (3.0000, -1.0000, -1.0000)>
<Vector (3.0000, -1.0000, 1.0000)>
<Vector (3.0000, 1.0000, -1.0000)>
<Vector (3.0000, 1.0000, 1.0000)>
Light

---

So my question is, why does the information reported by the Python function not show the new positions until I leave edit mode? Is there a cached copy of the vertex information, and the "real" data is not updated until exiting edit mode?

---

This was with Blender 2.80.57, however the same behaviour was observed in version 2.79.

Answer 1

I think you just need to call the update_from_editmode () method of the object. https://docs.blender.org/api/2.79/bpy.types.Object.html?highlight=update_from#bpy.types.Object.update_from_editmode