depsgraph_update_pre is not triggered on manual depsgraph update #113930

New Issue

Andrej · 2023-10-19T12:21:43+02:00

Andrej commented

2023-10-19 12:21:43 +02:00

Blender 3.6.4

Typically bpy.context.view_layer.update() is used to update depsgraph manually but it doesn't seem to trigger depsgraph_update_pre handler. I also tried multiple other ways to update depsgraph and none of them trigger the handler too.

The workaround is to call some other operator, it will trigger the handler. But need to make sure to change hide_render, hide_select, hide_viewport of some object, otherwise it wouldn't work.

What expected - manual depsgraph update to trigger the callbacks added to depsgraph_update_pre handler

The use case was trying to make automated tests for blender addon and was trying to make a way to trigger depsgraph_update_pre when Blender is running in background mode.

Empty blender scene, select cube.
Run the code below.
Run operator "Depsgraph Update Manual" from F3 menu. despgraph_pre_handler will triggered after empty_operator call.
change if True to if False - despgraph_pre_handler won't be triggered even after empty_operator call.

Code output:

operator started
----------------> view_layer update
----------------> evaluated_depsgraph_get update
----------------> hide_render change
----------------> hide_select  change
----------------> hide_viewport change
calling another operator
despgraph_pre_handler_triggered
operator has finished


import bpy
from bpy.app.handlers import persistent

class UpdateDepsgraphManual(bpy.types.Operator):
    bl_idname = "object.update_depsgraph_manual"
    bl_label = "Depsgraph Update Manual"
    bl_options = {"REGISTER", "UNDO"}

    def execute(self, context):
        print('operator started')
        print('----------------> view_layer update')
        bpy.context.view_layer.update()
        print('----------------> evaluated_depsgraph_get update')
        bpy.context.evaluated_depsgraph_get().update()

        # NOTE: if changed to False then `bpy.ops.object.empty_operator` wouldnt trigger
        # depsgraph update either
        if True:
            obj = context.object
            print('----------------> hide_render change')
            obj.hide_render = obj.hide_render
            print('----------------> hide_select  change')
            obj.hide_select  = obj.hide_select 
            print('----------------> hide_viewport change')
            obj.hide_viewport = obj.hide_viewport

        print('calling another operator')
        bpy.ops.object.empty_operator()

        print('operator has finished')
        return {'FINISHED'}
    
class EmptyOperator(bpy.types.Operator):
    bl_idname = "object.empty_operator"
    bl_label = "Empty Operator"
    bl_options = {"REGISTER", "UNDO"}

    def execute(self, context):
        return {'FINISHED'}

@persistent
def depsgraph_update_pre_handler(scene):
    print('despgraph_pre_handler_triggered')

def register():
    bpy.app.handlers.depsgraph_update_pre.append(depsgraph_update_pre_handler)
    bpy.utils.register_class(UpdateDepsgraphManual)
    bpy.utils.register_class(EmptyOperator)

if __name__ == "__main__":
    register()

Blender 3.6.4 Typically `bpy.context.view_layer.update()` is used to update depsgraph manually but it doesn't seem to trigger `depsgraph_update_pre` handler. I also tried multiple other ways to update depsgraph and none of them trigger the handler too. The workaround is to call some other operator, it will trigger the handler. But need to make sure to change `hide_render`, `hide_select`, `hide_viewport` of some object, otherwise it wouldn't work. What expected - manual depsgraph update to trigger the callbacks added to `depsgraph_update_pre` handler The use case was trying to make automated tests for blender addon and was trying to make a way to trigger `depsgraph_update_pre` when Blender is running in background mode. 1. Empty blender scene, select cube. 2. Run the code below. 3. Run operator "Depsgraph Update Manual" from F3 menu. `despgraph_pre_handler` will triggered after `empty_operator` call. 4. change `if True` to `if False` - `despgraph_pre_handler` won't be triggered even after `empty_operator` call. Code output: ``` operator started ----------------> view_layer update ----------------> evaluated_depsgraph_get update ----------------> hide_render change ----------------> hide_select change ----------------> hide_viewport change calling another operator despgraph_pre_handler_triggered operator has finished ``` ```python import bpy from bpy.app.handlers import persistent class UpdateDepsgraphManual(bpy.types.Operator): bl_idname = "object.update_depsgraph_manual" bl_label = "Depsgraph Update Manual" bl_options = {"REGISTER", "UNDO"} def execute(self, context): print('operator started') print('----------------> view_layer update') bpy.context.view_layer.update() print('----------------> evaluated_depsgraph_get update') bpy.context.evaluated_depsgraph_get().update() # NOTE: if changed to False then `bpy.ops.object.empty_operator` wouldnt trigger # depsgraph update either if True: obj = context.object print('----------------> hide_render change') obj.hide_render = obj.hide_render print('----------------> hide_select change') obj.hide_select = obj.hide_select print('----------------> hide_viewport change') obj.hide_viewport = obj.hide_viewport print('calling another operator') bpy.ops.object.empty_operator() print('operator has finished') return {'FINISHED'} class EmptyOperator(bpy.types.Operator): bl_idname = "object.empty_operator" bl_label = "Empty Operator" bl_options = {"REGISTER", "UNDO"} def execute(self, context): return {'FINISHED'} @persistent def depsgraph_update_pre_handler(scene): print('despgraph_pre_handler_triggered') def register(): bpy.app.handlers.depsgraph_update_pre.append(depsgraph_update_pre_handler) bpy.utils.register_class(UpdateDepsgraphManual) bpy.utils.register_class(EmptyOperator) if __name__ == "__main__": register() ```

Andrej added the

labels 2023-10-19 12:21:44 +02:00

Iliya Katushenock added the