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Maniphest T44168

Selection issue on masked geometry
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Description

System Information
Windows 7 64, GTX 980

Blender Version
Broken: bbf09d9 + 469ba8a

Short description of error
"Select All" (Ctrl-A) selects masked geometry as well if you use a Mask modifier to hide it (with enabled edit cage).

This behaviour isnt the case for hidden geometry (H), so i think there might be a bug.

Exact steps for others to reproduce the error

MaskGeometryBug.blend737 KBDownload

Steps:

  • Add a monkey mesh
    • Give it a vertex group "Group"
    • Assign one half of the head to "Group"
  • Give monkey a Mask modifier
    • Choose "Group" as modifier vertex group
    • Deselect all geometry
    • Enable Edit Cage Mode

You should have a halfed monkey head now.

  • Still in Edit Mode, select all visible geometry (Ctrl-A)
  • Assign "Group" again on the already assigned visible part

Problem:
Unexpectedly, the monkey head has returned completely,
because (Ctrl-A) has included the hidden geometry.

Note:
This behaviour is likely to cause confusion at a later time if you use Mask modifier as a method for Vertex Group weighting.

Related Objects

Event Timeline

Karja Krähwald (karja) created this task.Mar 28 2015, 4:20 PM
Karja Krähwald (karja) raised the priority of this task from to 90.
Karja Krähwald (karja) updated the task description. (Show Details)
Karja Krähwald (karja) added projects: BF Blender, Modifiers.
Karja Krähwald (karja) edited a custom field.
Karja Krähwald (karja) added a subscriber: Karja Krähwald (karja).
Bastien Montagne (mont29) added subscribers: Campbell Barton (campbellbarton), Bastien Montagne (mont29).Mar 30 2015, 11:19 AM

Campbell, need your advice here.

To me there is no bug, operators do not work on modifiers' result, only on raw mesh usually, so it’s expected that 'select all' does not take into account geometry hidden by mask modifier…

Bastien Montagne (mont29) lowered the priority of this task from 90 to Normal.Mar 30 2015, 11:19 AM
Campbell Barton (campbellbarton) changed the task status from Unknown Status to Archived.Mar 30 2015, 12:19 PM
Campbell Barton (campbellbarton) claimed this task.

@Bastien Montagne (mont29), right - even allowing the mask modifier to operate in edit-mode is questionable (since it can hide what is really happening to the mesh).

Checked no the modifier stack and there isn't any good way to disable *cage* on a modifier, (which would be reasonable in this case, but probably not worth supporting just for this case).

closing.