I was under impression when I change the values of properties of operator, every time the operator is executed it runs on a snapshot of the mesh that was taken when the operator was invoked.
For instance, my operator manipulates the mesh, extrudes it and assigns values to custom properties via layers. As I see it, every time I change the property value, the operator is applied to the mesh that was changed by previous execution of the operator. Perhaps it has something to do with manipulating the mesh via bmesh.
Long story short, this is more or less what I do:
if bpy.context.mode != 'EDIT':
bpy.ops.object.mode_set(mode = 'EDIT')
mesh = bmesh.from_edit_mesh(context.active_object.data)
fieldTypeLayer = mesh.faces.layers.int.get(pu.fieldTypeLayerName)
for face in mesh.faces:
face[fieldTypeLayer] = somealue
extrudeVector = somevalue
bpy.ops.mesh.extrude_region_move(params)
bmesh.update_edit_mesh(context.active_object.data)
So basically, do I need to save a snapshot of a mesh on operator invoke and then before each execution restore our mesh from it, or am I missing something and blender is supposed to do it for me?
If you run operators with Redo support in the UI, the operator properties will show up in the Redo panel. On every change to these properties, the operation is reverted and re-executed with the new parameters (can’t tell you whether a snapshot technically exists though, but I would say yes).
If your own operator has the ‘REDO’ option set, an undo step should automatically be pushed to the stack. Otherwise you would need to push manually.
I had some read about how operators are executed, and so far I can’t understand how my operator is different. Perhaps it’s the way I update my edit mesh with bmesh, not sure.
bl_options = {'REGISTER', 'UNDO', 'PRESET'}
This is how my operator defined, that’s how all of my operators are defined, and all of them actually revert the mesh before executing the operator again. So your suggestions is to add ‘REDO’ to bl_options?
Never mind, it’s actually ‘UNDO’ - it’s kinda both. Undo support needs to be enabled in order to support the Redo functionality.
Note that you need to use operator properties and run the operator via a button, shortcut or spacebar menu. It won’t work (nothing shown in Redo panel) if you execute the operator from Text Editor or Python console. The entire operator will be re-run as you change properties in the redo panel via mouse drag or keyboard input - regardless of other operators that might be called inside your operator.
